KrebsOnSecurity

Late last year, security researchers made a startling discovery: Kremlin-backed disinformation campaigns were bypassing moderation on social media platforms by leveraging the same malicious advertising technology that powers a sprawling ecosystem of online hucksters and website hackers. A new report on the fallout from that investigation finds this dark ad tech industry is far more resilient and incestuous than previously known.

Image: Infoblox.

In November 2024, researchers at the security firm Qurium published an investigation into “Doppelganger,” a disinformation network that promotes pro-Russian narratives and infiltrates Europe’s media landscape by pushing fake news through a network of cloned websites.

Doppelganger campaigns use specialized links that bounce the visitor’s browser through a long series of domains before the fake news content is served. Qurium found Doppelganger relies on a sophisticated “domain cloaking” service, a technology that allows websites to present different content to search engines compared to what regular visitors see. The use of cloaking services helps the disinformation sites remain online longer than they otherwise would, while ensuring that only the targeted audience gets to view the intended content.

Qurium discovered that Doppelganger’s cloaking service also promoted online dating sites, and shared much of the same infrastructure with VexTrio, which is thought to be the oldest malicious traffic distribution system (TDS) in existence. While TDSs are commonly used by legitimate advertising networks to manage traffic from disparate sources and to track who or what is behind each click, VexTrio’s TDS largely manages web traffic from victims of phishing, malware, and social engineering scams.

BREAKING BAD

Digging deeper, Qurium noticed Doppelganger’s cloaking service used an Internet provider in Switzerland as the first entry point in a chain of domain redirections. They also noticed the same infrastructure hosted a pair of co-branded affiliate marketing services that were driving traffic to sketchy adult dating sites: LosPollos[.]com and TacoLoco[.]co.

The LosPollos ad network incorporates many elements and references from the hit HBO series “Breaking Bad,” mirroring the fictional “Los Pollos Hermanos” restaurant chain that served as a money laundering operation for a violent methamphetamine cartel.

The LosPollos advertising network invokes characters and themes from the hit show Breaking Bad. The logo for LosPollos (upper left) is the image of Gustavo Fring, the fictional chicken restaurant chain owner in the show.

Affiliates who sign up with LosPollos are given JavaScript-heavy “smartlinks” that drive traffic into the VexTrio TDS, which in turn distributes the traffic among a variety of advertising partners, including dating services, sweepstakes offers, bait-and-switch mobile apps, financial scams and malware download sites.

LosPollos affiliates typically stitch these smart links into WordPress websites that have been hacked via known vulnerabilities, and those affiliates will earn a small commission each time an Internet user referred by any of their hacked sites falls for one of these lures.

The Los Pollos advertising network promoting itself on LinkedIn.

According to Qurium, TacoLoco is a traffic monetization network that uses deceptive tactics to trick Internet users into enabling “push notifications,” a cross-platform browser standard that allows websites to show pop-up messages which appear outside of the browser. For example, on Microsoft Windows systems these notifications typically show up in the bottom right corner of the screen — just above the system clock.

In the case of VexTrio and TacoLoco, the notification approval requests themselves are deceptive — disguised as “CAPTCHA” challenges designed to distinguish automated bot traffic from real visitors. For years, VexTrio and its partners have successfully tricked countless users into enabling these site notifications, which are then used to continuously pepper the victim’s device with a variety of phony virus alerts and misleading pop-up messages.

Examples of VexTrio landing pages that lead users to accept push notifications on their device.

According to a December 2024 annual report from GoDaddy, nearly 40 percent of compromised websites in 2024 redirected visitors to VexTrio via LosPollos smartlinks.

ADSPRO AND TEKNOLOGY

On November 14, 2024, Qurium published research to support its findings that LosPollos and TacoLoco were services operated by Adspro Group, a company registered in the Czech Republic and Russia, and that Adspro runs its infrastructure at the Swiss hosting providers C41 and Teknology SA.

Qurium noted the LosPollos and TacoLoco sites state that their content is copyrighted by ByteCore AG and SkyForge Digital AG, both Swiss firms that are run by the owner of Teknology SA, Guilio Vitorrio Leonardo Cerutti. Further investigation revealed LosPollos and TacoLoco were apps developed by a company called Holacode, which lists Cerutti as its CEO.

The apps marketed by Holacode include numerous VPN services, as well as one called Spamshield that claims to stop unwanted push notifications. But in January, Infoblox said they tested the app on their own mobile devices, and found it hides the user’s notifications, and then after 24 hours stops hiding them and demands payment. Spamshield subsequently changed its developer name from Holacode to ApLabz, although Infoblox noted that the Terms of Service for several of the rebranded ApLabz apps still referenced Holacode in their terms of service.

Incredibly, Cerutti threatened to sue me for defamation before I’d even uttered his name or sent him a request for comment (Cerutti sent the unsolicited legal threat back in January after his company and my name were merely tagged in an Infoblox post on LinkedIn about VexTrio).

Asked to comment on the findings by Qurium and Infoblox, Cerutti vehemently denied being associated with VexTrio. Cerutti asserted that his companies all strictly adhere to the regulations of the countries in which they operate, and that they have been completely transparent about all of their operations.

“We are a group operating in the advertising and marketing space, with an affiliate network program,” Cerutti responded. “I am not [going] to say we are perfect, but I strongly declare we have no connection with VexTrio at all.”

“Unfortunately, as a big player in this space we also get to deal with plenty of publisher fraud, sketchy traffic, fake clicks, bots, hacked, listed and resold publisher accounts, etc, etc.,” Cerutti continued. “We bleed lots of money to such malpractices and conduct regular internal screenings and audits in a constant battle to remove bad traffic sources. It is also a highly competitive space, where some upstarts will often play dirty against more established mainstream players like us.”

Working with Qurium, researchers at the security firm Infoblox released details about VexTrio’s infrastructure to their industry partners. Just four days after Qurium published its findings, LosPollos announced it was suspending its push monetization service. Less than a month later, Adspro had rebranded to Aimed Global.

A mind map illustrating some of the key findings and connections in the Infoblox and Qurium investigations. Click to enlarge.

A REVEALING PIVOT

In March 2025, researchers at GoDaddy chronicled how DollyWay — a malware strain that has consistently redirected victims to VexTrio throughout its eight years of activity — suddenly stopped doing that on November 20, 2024. Virtually overnight, DollyWay and several other malware families that had previously used VexTrio began pushing their traffic through another TDS called Help TDS.

Digging further into historical DNS records and the unique code scripts used by the Help TDS, Infoblox determined it has long enjoyed an exclusive relationship with VexTrio (at least until LosPollos ended its push monetization service in November).

In a report released today, Infoblox said an exhaustive analysis of the JavaScript code, website lures, smartlinks and DNS patterns used by VexTrio and Help TDS linked them with at least four other TDS operators (not counting TacoLoco). Those four entities — Partners House, BroPush, RichAds and RexPush — are all Russia-based push monetization programs that pay affiliates to drive signups for a variety of schemes, but mostly online dating services.

“As Los Pollos push monetization ended, we’ve seen an increase in fake CAPTCHAs that drive user acceptance of push notifications, particularly from Partners House,” the Infoblox report reads. “The relationship of these commercial entities remains a mystery; while they are certainly long-time partners redirecting traffic to one another, and they all have a Russian nexus, there is no overt common ownership.”

Renee Burton, vice president of threat intelligence at Infoblox, said the security industry generally treats the deceptive methods used by VexTrio and other malicious TDSs as a kind of legally grey area that is mostly associated with less dangerous security threats, such as adware and scareware.

But Burton argues that this view is myopic, and helps perpetuate a dark adtech industry that also pushes plenty of straight-up malware, noting that hundreds of thousands of compromised websites around the world every year redirect victims to the tangled web of VexTrio and VexTrio-affiliate TDSs.

“These TDSs are a nefarious threat, because they’re the ones you can connect to the delivery of things like information stealers and scams that cost consumers billions of dollars a year,” Burton said. “From a larger strategic perspective, my takeaway is that Russian organized crime has control of malicious adtech, and these are just some of the many groups involved.”

WHAT CAN YOU DO?

As KrebsOnSecurity warned way back in 2020, it’s a good idea to be very sparing in approving notifications when browsing the Web. In many cases these notifications are benign, but as we’ve seen there are numerous dodgy firms that are paying site owners to install their notification scripts, and then reselling that communications pathway to scammers and online hucksters.

If you’d like to prevent sites from ever presenting notification requests, all of the major browser makers let you do this — either across the board or on a per-website basis. While it is true that blocking notifications entirely can break the functionality of some websites, doing this for any devices you manage on behalf of your less tech-savvy friends or family members might end up saving everyone a lot of headache down the road.

To modify site notification settings in Mozilla Firefox, navigate to Settings, Privacy & Security, Permissions, and click the “Settings” tab next to “Notifications.” That page will display any notifications already permitted and allow you to edit or delete any entries. Tick the box next to “Block new requests asking to allow notifications” to stop them altogether.

In Google Chrome, click the icon with the three dots to the right of the address bar, scroll all the way down to Settings, Privacy and Security, Site Settings, and Notifications. Select the “Don’t allow sites to send notifications” button if you want to banish notification requests forever.

In Apple’s Safari browser, go to Settings, Websites, and click on Notifications in the sidebar. Uncheck the option to “allow websites to ask for permission to send notifications” if you wish to turn off notification requests entirely.

Microsoft today released security updates to fix at least 67 vulnerabilities in its Windows operating systems and software. Redmond warns that one of the flaws is already under active attack, and that software blueprints showing how to exploit a pervasive Windows bug patched this month are now public.

The sole zero-day flaw this month is CVE-2025-33053, a remote code execution flaw in the Windows implementation of WebDAV — an HTTP extension that lets users remotely manage files and directories on a server. While WebDAV isn’t enabled by default in Windows, its presence in legacy or specialized systems still makes it a relevant target, said Seth Hoyt, senior security engineer at Automox.

Adam Barnett, lead software engineer at Rapid7, said Microsoft’s advisory for CVE-2025-33053 does not mention that the Windows implementation of WebDAV is listed as deprecated since November 2023, which in practical terms means that the WebClient service no longer starts by default.

“The advisory also has attack complexity as low, which means that exploitation does not require preparation of the target environment in any way that is beyond the attacker’s control,” Barnett said. “Exploitation relies on the user clicking a malicious link. It’s not clear how an asset would be immediately vulnerable if the service isn’t running, but all versions of Windows receive a patch, including those released since the deprecation of WebClient, like Server 2025 and Windows 11 24H2.”

Microsoft warns that an “elevation of privilege” vulnerability in the Windows Server Message Block (SMB) client (CVE-2025-33073) is likely to be exploited, given that proof-of-concept code for this bug is now public. CVE-2025-33073 has a CVSS risk score of 8.8 (out of 10), and exploitation of the flaw leads to the attacker gaining “SYSTEM” level control over a vulnerable PC.

“What makes this especially dangerous is that no further user interaction is required after the initial connection—something attackers can often trigger without the user realizing it,” said Alex Vovk, co-founder and CEO of Action1. “Given the high privilege level and ease of exploitation, this flaw poses a significant risk to Windows environments. The scope of affected systems is extensive, as SMB is a core Windows protocol used for file and printer sharing and inter-process communication.”

Beyond these highlights, 10 of the vulnerabilities fixed this month were rated “critical” by Microsoft, including eight remote code execution flaws.

Notably absent from this month’s patch batch is a fix for a newly discovered weakness in Windows Server 2025 that allows attackers to act with the privileges of any user in Active Directory. The bug, dubbed “BadSuccessor,” was publicly disclosed by researchers at Akamai on May 21, and several public proof-of-concepts are now available. Tenable’s Satnam Narang said organizations that have at least one Windows Server 2025 domain controller should review permissions for principals and limit those permissions as much as possible.

Adobe has released updates for Acrobat Reader and six other products addressing at least 259 vulnerabilities, most of them in an update for Experience Manager. Mozilla Firefox and Google Chrome both recently released security updates that require a restart of the browser to take effect. The latest Chrome update fixes two zero-day exploits in the browser (CVE-2025-5419 and CVE-2025-4664).

For a detailed breakdown on the individual security updates released by Microsoft today, check out the Patch Tuesday roundup from the SANS Internet Storm Center. Action 1 has a breakdown of patches from Microsoft and a raft of other software vendors releasing fixes this month. As always, please back up your system and/or data before patching, and feel free to drop a note in the comments if you run into any problems applying these updates.

Image: Mark Rademaker, via Shutterstock.

Ukraine has seen nearly one-fifth of its Internet space come under Russian control or sold to Internet address brokers since February 2022, a new study finds. The analysis indicates large chunks of Ukrainian Internet address space are now in the hands of shadowy proxy and anonymity services that are nested at some of America’s largest Internet service providers (ISPs).

The findings come in a report that examines how the Russian invasion has affected Ukraine’s domestic supply of Internet Protocol Version 4 (IPv4) addresses. Researchers at Kentik, a company that measures the performance of Internet networks, found that while a majority of ISPs in Ukraine haven’t changed their infrastructure much since the war began in 2022, others have resorted to selling swathes of their valuable IPv4 address space just to keep the lights on.

For example, Ukraine’s incumbent ISP Ukrtelecom is now routing just 29 percent of the IPv4 address ranges that the company controlled at the start of the war, Kentik found. Although much of that former IP space remains dormant, Ukrtelecom told Kentik’s Doug Madory they were forced to sell many of their address blocks “to secure financial stability and continue delivering essential services.”

“Leasing out a portion of our IPv4 resources allowed us to mitigate some of the extraordinary challenges we have been facing since the full-scale invasion began,” Ukrtelecom told Madory.

Madory found much of the IPv4 space previously allocated to Ukrtelecom is now scattered to more than 100 providers globally, particularly at three large American ISPs — Amazon (AS16509), AT&T (AS7018), and Cogent (AS174).

Another Ukrainian Internet provider — LVS (AS43310) — in 2022 was routing approximately 6,000 IPv4 addresses across the nation. Kentik learned that by November 2022, much of that address space had been parceled out to over a dozen different locations, with the bulk of it being announced at AT&T.

IP addresses routed over time by Ukrainian provider LVS (AS43310) shows a large chunk of it being routed by AT&T (AS7018). Image: Kentik.

Ditto for the Ukrainian ISP TVCOM, which currently routes nearly 15,000 fewer IPv4 addresses than it did at the start of the war. Madory said most of those addresses have been scattered to 37 other networks outside of Eastern Europe, including Amazon, AT&T, and Microsoft.

The Ukrainian ISP Trinity (AS43554) went offline in early March 2022 during the bloody siege of Mariupol, but its address space eventually began showing up in more than 50 different networks worldwide. Madory found more than 1,000 of Trinity’s IPv4 addresses suddenly appeared on AT&T’s network.

Why are all these former Ukrainian IP addresses being routed by U.S.-based networks like AT&T? According to spur.us, a company that tracks VPN and proxy services, nearly all of the address ranges identified by Kentik now map to commercial proxy services that allow customers to anonymously route their Internet traffic through someone else’s computer.

From a website’s perspective, the traffic from a proxy network user appears to originate from the rented IP address, not from the proxy service customer. These services can be used for several business purposes, such as price comparisons, sales intelligence, web crawlers and content-scraping bots. However, proxy services also are massively abused for hiding cybercrime activity because they can make it difficult to trace malicious traffic to its original source.

IPv4 address ranges are always in high demand, which means they are also quite valuable. There are now multiple companies that will pay ISPs to lease out their unwanted or unused IPv4 address space. Madory said these IPv4 brokers will pay between $100-$500 per month to lease a block of 256 IPv4 addresses, and very often the entities most willing to pay those rental rates are proxy and VPN providers.

A cursory review of all Internet address blocks currently routed through AT&T — as seen in public records maintained by the Internet backbone provider Hurricane Electric — shows a preponderance of country flags other than the United States, including networks originating in Hungary, Lithuania, Moldova, Mauritius, Palestine, Seychelles, Slovenia, and Ukraine.

AT&T’s IPv4 address space seems to be routing a great deal of proxy traffic, including a large number of IP address ranges that were until recently routed by ISPs in Ukraine.

Asked about the apparent high incidence of proxy services routing foreign address blocks through AT&T, the telecommunications giant said it recently changed its policy about originating routes for network blocks that are not owned and managed by AT&T. That new policy, spelled out in a February 2025 update to AT&T’s terms of service, gives those customers until Sept. 1, 2025 to originate their own IP space from their own autonomous system number (ASN), a unique number assigned to each ISP (AT&T’s is AS7018).

“To ensure our customers receive the best quality of service, we changed our terms for dedicated internet in February 2025,” an AT&T spokesperson said in an emailed reply. “We no longer permit static routes with IP addresses that we have not provided. We have been in the process of identifying and notifying affected customers that they have 90 days to transition to Border Gateway Protocol routing using their own autonomous system number.”

Ironically, the co-mingling of Ukrainian IP address space with proxy providers has resulted in many of these addresses being used in cyberattacks against Ukraine and other enemies of Russia. Earlier this month, the European Union sanctioned Stark Industries Solutions Inc., an ISP that surfaced two weeks before the Russian invasion and quickly became the source of large-scale DDoS attacks and spear-phishing attempts by Russian state-sponsored hacking groups. A deep dive into Stark’s considerable address space showed some of it was sourced from Ukrainian ISPs, and most of it was connected to Russia-based proxy and anonymity services.

According to Spur, the proxy service IPRoyal is the current beneficiary of IP address blocks from several Ukrainian ISPs profiled in Kentik’s report. Customers can chose proxies by specifying the city and country they would to proxy their traffic through. Image: Trend Micro.

Spur’s Chief Technology Officer Riley Kilmer said AT&T’s policy change will likely force many proxy services to migrate to other U.S. providers that have less stringent policies.

“AT&T is the first one of the big ISPs that seems to be actually doing something about this,” Kilmer said. “We track several services that explicitly sell AT&T IP addresses, and it will be very interesting to see what happens to those services come September.”

Still, Kilmer said, there are several other large U.S. ISPs that continue to make it easy for proxy services to bring their own IP addresses and host them in ranges that give the appearance of residential customers. For example, Kentik’s report identified former Ukrainian IP ranges showing up as proxy services routed by Cogent Communications (AS174), a tier-one Internet backbone provider based in Washington, D.C.

Kilmer said Cogent has become an attractive home base for proxy services because it is relatively easy to get Cogent to route an address block.

“In fairness, they transit a lot of traffic,” Kilmer said of Cogent. “But there’s a reason a lot of this proxy stuff shows up as Cogent: Because it’s super easy to get something routed there.”

Cogent declined a request to comment on Kentik’s findings.

Image: Shutterstock, ArtHead.

The U.S. government today imposed economic sanctions on Funnull Technology Inc., a Philippines-based company that provides computer infrastructure for hundreds of thousands of websites involved in virtual currency investment scams known as “pig butchering.” In January 2025, KrebsOnSecurity detailed how Funnull was being used as a content delivery network that catered to cybercriminals seeking to route their traffic through U.S.-based cloud providers.

“Americans lose billions of dollars annually to these cyber scams, with revenues generated from these crimes rising to record levels in 2024,” reads a statement from the U.S. Department of the Treasury, which sanctioned Funnull and its 40-year-old Chinese administrator Liu Lizhi. “Funnull has directly facilitated several of these schemes, resulting in over $200 million in U.S. victim-reported losses.”

The Treasury Department said Funnull’s operations are linked to the majority of virtual currency investment scam websites reported to the FBI. The agency said Funnull directly facilitated pig butchering and other schemes that resulted in more than $200 million in financial losses by Americans.

Pig butchering is a rampant form of fraud wherein people are lured by flirtatious strangers online into investing in fraudulent cryptocurrency trading platforms. Victims are coached to invest more and more money into what appears to be an extremely profitable trading platform, only to find their money is gone when they wish to cash out.

The scammers often insist that investors pay additional “taxes” on their crypto “earnings” before they can see their invested funds again (spoiler: they never do), and a shocking number of people have lost six figures or more through these pig butchering scams.

KrebsOnSecurity’s January story on Funnull was based on research from the security firm Silent Push, which discovered in October 2024 that a vast number of domains hosted via Funnull were promoting gambling sites that bore the logo of the Suncity Group, a Chinese entity named in a 2024 UN report (PDF) for laundering millions of dollars for the North Korean state-sponsored hacking group Lazarus.

Silent Push found Funnull was a criminal content delivery network (CDN) that carried a great deal of traffic tied to scam websites, funneling the traffic through a dizzying chain of auto-generated domain names and U.S.-based cloud providers before redirecting to malicious or phishous websites. The FBI has released a technical writeup (PDF) of the infrastructure used to manage the malicious Funnull domains between October 2023 and April 2025.

A graphic from the FBI explaining how Funnull generated a slew of new domains on a regular basis and mapped them to Internet addresses on U.S. cloud providers.

Silent Push revisited Funnull’s infrastructure in January 2025 and found Funnull was still using many of the same Amazon and Microsoft cloud Internet addresses identified as malicious in its October report. Both Amazon and Microsoft pledged to rid their networks of Funnull’s presence following that story, but according to Silent Push’s Zach Edwards only one of those companies has followed through.

Edwards said Silent Push no longer sees Microsoft Internet addresses showing up in Funnull’s infrastructure, while Amazon continues to struggle with removing Funnull servers, including one that appears to have first materialized in 2023.

“Amazon is doing a terrible job — every day since they made those claims to you and us in our public blog they have had IPs still mapped to Funnull, including some that have stayed mapped for inexplicable periods of time,” Edwards said.

Amazon said its Amazon Web Services (AWS) hosting platform actively counters abuse attempts.

“We have stopped hundreds of attempts this year related to this group and we are looking into the information you shared earlier today,” reads a statement shared by Amazon. “If anyone suspects that AWS resources are being used for abusive activity, they can report it to AWS Trust & Safety using the report abuse form here.”

U.S. based cloud providers remain an attractive home base for cybercriminal organizations because many organizations will not be overly aggressive in blocking traffic from U.S.-based cloud networks, as doing so can result in blocking access to many legitimate web destinations that are also on that same shared network segment or host.

What’s more, funneling their bad traffic so that it appears to be coming out of U.S. cloud Internet providers allows cybercriminals to connect to websites from web addresses that are geographically close(r) to their targets and victims (to sidestep location-based security controls by your bank, for example).

Funnull is not the only cybercriminal infrastructure-as-a-service provider that was sanctioned this month: On May 20, 2025, the European Union imposed sanctions on Stark Industries Solutions, an ISP that materialized at the start of Russia’s invasion of Ukraine and has been used as a global proxy network that conceals the true source of cyberattacks and disinformation campaigns against enemies of Russia.

In May 2024, KrebsOnSecurity published a deep dive on Stark Industries Solutions that found much of the malicious traffic traversing Stark’s network (e.g. vulnerability scanning and password brute force attacks) was being bounced through U.S.-based cloud providers. My reporting showed how deeply Stark had penetrated U.S. ISPs, and that Ivan Neculiti for many years sold “bulletproof” hosting services that told Russian cybercrime forum customers they would proudly ignore any abuse complaints or police inquiries.

The homepage of Stark Industries Solutions.

That story examined the history of Stark’s co-founders, Moldovan brothers Ivan and Yuri Neculiti, who each denied past involvement in cybercrime or any current involvement in assisting Russian disinformation efforts or cyberattacks. Nevertheless, the EU sanctioned both brothers as well.

The EU said Stark and the Neculti brothers “enabled various Russian state-sponsored and state-affiliated actors to conduct destabilising activities including coordinated information manipulation and interference and cyber-attacks against the Union and third countries by providing services intended to hide these activities from European law enforcement and security agencies.”

Authorities in Pakistan have arrested 21 individuals accused of operating “Heartsender,” a once popular spam and malware dissemination service that operated for more than a decade. The main clientele for HeartSender were organized crime groups that tried to trick victim companies into making payments to a third party, and its alleged proprietors were publicly identified by KrebsOnSecurity in 2021 after they inadvertently infected their computers with malware.

Some of the core developers and sellers of Heartsender posing at a work outing in 2021. WeCodeSolutions boss Rameez Shahzad (in sunglasses) is in the center of this group photo, which was posted by employee Burhan Ul Haq, pictured just to the right of Shahzad.

A report from the Pakistani media outlet Dawn states that authorities there arrested 21 people alleged to have operated Heartsender, a spam delivery service whose homepage openly advertised phishing kits targeting users of various Internet companies, including Microsoft 365, Yahoo, AOL, Intuit, iCloud and ID.me. Pakistan’s National Cyber Crime Investigation Agency (NCCIA) reportedly conducted raids in Lahore’s Bahria Town and Multan on May 15 and 16.

The NCCIA told reporters the group’s tools were connected to more than $50m in losses in the United States alone, with European authorities investigating 63 additional cases.

“This wasn’t just a scam operation – it was essentially a cybercrime university that empowered fraudsters globally,” NCCIA Director Abdul Ghaffar said at a press briefing.

In January 2025, the FBI and the Dutch Police seized the technical infrastructure for the cybercrime service, which was marketed under the brands Heartsender, Fudpage and Fudtools (and many other “fud” variations). The “fud” bit stands for “Fully Un-Detectable,” and it refers to cybercrime resources that will evade detection by security tools like antivirus software or anti-spam appliances.

The FBI says transnational organized crime groups that purchased these services primarily used them to run business email compromise (BEC) schemes, wherein the cybercrime actors tricked victim companies into making payments to a third party.

Dawn reported that those arrested included Rameez Shahzad, the alleged ringleader of the Heartsender cybercrime business, which most recently operated under the Pakistani front company WeCodeSolutions. Mr. Shahzad was named and pictured in a 2021 KrebsOnSecurity story about a series of remarkable operational security mistakes that exposed their identities and Facebook pages showing employees posing for group photos and socializing at work-related outings.

Prior to folding their operations behind WeCodeSolutions, Shahzad and others arrested this month operated as a web hosting group calling itself The Manipulaters. KrebsOnSecurity first wrote about The Manipulaters in May 2015, mainly because their ads at the time were blanketing a number of popular cybercrime forums, and because they were fairly open and brazen about what they were doing — even who they were in real life.

Sometime in 2019, The Manipulaters failed to renew their core domain name — manipulaters[.]com — the same one tied to so many of the company’s business operations. That domain was quickly scooped up by Scylla Intel, a cyber intelligence firm that specializes in connecting cybercriminals to their real-life identities. Soon after, Scylla started receiving large amounts of email correspondence intended for the group’s owners.

In 2024, DomainTools.com found the web-hosted version of Heartsender leaked an extraordinary amount of user information to unauthenticated users, including customer credentials and email records from Heartsender employees. DomainTools says the malware infections on Manipulaters PCs exposed “vast swaths of account-related data along with an outline of the group’s membership, operations, and position in the broader underground economy.”

Shahzad allegedly used the alias “Saim Raza,” an identity which has contacted KrebsOnSecurity multiple times over the past decade with demands to remove stories published about the group. The Saim Raza identity most recently contacted this author in November 2024, asserting they had quit the cybercrime industry and turned over a new leaf after a brush with the Pakistani police.

The arrested suspects include Rameez Shahzad, Muhammad Aslam (Rameez’s father), Atif Hussain, Muhammad Umar Irshad, Yasir Ali, Syed Saim Ali Shah, Muhammad Nowsherwan, Burhanul Haq, Adnan Munawar, Abdul Moiz, Hussnain Haider, Bilal Ahmad, Dilbar Hussain, Muhammad Adeel Akram, Awais Rasool, Usama Farooq, Usama Mehmood and Hamad Nawaz.

The U.S. government today unsealed criminal charges against 16 individuals accused of operating and selling DanaBot, a prolific strain of information-stealing malware that has been sold on Russian cybercrime forums since 2018. The FBI says a newer version of DanaBot was used for espionage, and that many of the defendants exposed their real-life identities after accidentally infecting their own systems with the malware.

DanaBot’s features, as promoted on its support site. Image: welivesecurity.com.

Initially spotted in May 2018 by researchers at the email security firm Proofpoint, DanaBot is a malware-as-a-service platform that specializes in credential theft and banking fraud.

Today, the U.S. Department of Justice unsealed a criminal complaint and indictment from 2022, which said the FBI identified at least 40 affiliates who were paying between $3,000 and $4,000 a month for access to the information stealer platform.

The government says the malware infected more than 300,000 systems globally, causing estimated losses of more than $50 million. The ringleaders of the DanaBot conspiracy are named as Aleksandr Stepanov, 39, a.k.a. “JimmBee,” and Artem Aleksandrovich Kalinkin, 34, a.k.a. “Onix”, both of Novosibirsk, Russia. Kalinkin is an IT engineer for the Russian state-owned energy giant Gazprom. His Facebook profile name is “Maffiozi.”

According to the FBI, there were at least two major versions of DanaBot; the first was sold between 2018 and June 2020, when the malware stopped being offered on Russian cybercrime forums. The government alleges that the second version of DanaBot — emerging in January 2021 — was provided to co-conspirators for use in targeting military, diplomatic and non-governmental organization computers in several countries, including the United States, Belarus, the United Kingdom, Germany, and Russia.

“Unindicted co-conspirators would use the Espionage Variant to compromise computers around the world and steal sensitive diplomatic communications, credentials, and other data from these targeted victims,” reads a grand jury indictment dated Sept. 20, 2022. “This stolen data included financial transactions by diplomatic staff, correspondence concerning day-to-day diplomatic activity, as well as summaries of a particular country’s interactions with the United States.”

The indictment says the FBI in 2022 seized servers used by the DanaBot authors to control their malware, as well as the servers that stored stolen victim data. The government said the server data also show numerous instances in which the DanaBot defendants infected their own PCs, resulting in their credential data being uploaded to stolen data repositories that were seized by the feds.

“In some cases, such self-infections appeared to be deliberately done in order to test, analyze, or improve the malware,” the criminal complaint reads. “In other cases, the infections seemed to be inadvertent – one of the hazards of committing cybercrime is that criminals will sometimes infect themselves with their own malware by mistake.”

Image: welivesecurity.com

A statement from the DOJ says that as part of today’s operation, agents with the Defense Criminal Investigative Service (DCIS) seized the Danabot control servers, including dozens of virtual servers hosted in the United States. The government says it is now working with industry partners to notify DanaBot victims and help remediate infections. The statement credits a number of security firms with providing assistance to the government, including ESET, Flashpoint, Google, Intel 471, Lumen, PayPal, Proofpoint, Team CYRMU, and ZScaler.

It’s not unheard of for financially-oriented malicious software to be repurposed for espionage. A variant of the ZeuS Trojan, which was used in countless online banking attacks against companies in the United States and Europe between 2007 and at least 2015, was for a time diverted to espionage tasks by its author.

As detailed in this 2015 story, the author of the ZeuS trojan created a custom version of the malware to serve purely as a spying machine, which scoured infected systems in Ukraine for specific keywords in emails and documents that would likely only be found in classified documents.

The public charging of the 16 DanaBot defendants comes a day after Microsoft joined a slew of tech companies in disrupting the IT infrastructure for another malware-as-a-service offering — Lumma Stealer, which is likewise offered to affiliates under tiered subscription prices ranging from $250 to $1,000 per month. Separately, Microsoft filed a civil lawsuit to seize control over 2,300 domain names used by Lumma Stealer and its affiliates.

Further reading:

Danabot: Analyzing a Fallen Empire

ZScaler blog: DanaBot Launches DDoS Attack Against the Ukrainian Ministry of Defense

Flashpoint: Operation Endgame DanaBot Malware

March 2022 criminal complaint v. Artem Aleksandrovich Kalinkin

September 2022 grand jury indictment naming the 16 defendants

KrebsOnSecurity last week was hit by a near record distributed denial-of-service (DDoS) attack that clocked in at more than 6.3 terabits of data per second (a terabit is one trillion bits of data). The brief attack appears to have been a test run for a massive new Internet of Things (IoT) botnet capable of launching crippling digital assaults that few web destinations can withstand. Read on for more about the botnet, the attack, and the apparent creator of this global menace.

For reference, the 6.3 Tbps attack last week was ten times the size of the assault launched against this site in 2016 by the Mirai IoT botnet, which held KrebsOnSecurity offline for nearly four days. The 2016 assault was so large that Akamai – which was providing pro-bono DDoS protection for KrebsOnSecurity at the time — asked me to leave their service because the attack was causing problems for their paying customers.

Since the Mirai attack, KrebsOnSecurity.com has been behind the protection of Project Shield, a free DDoS defense service that Google subsidiary Jigsaw provides to websites offering news, human rights, and election-related content. Google Security Engineer Damian Menscher told KrebsOnSecurity the May 12 attack was the largest Google has ever handled. In terms of sheer size, it is second only to a very similar attack that Cloudflare mitigated and wrote about in April.

After comparing notes with Cloudflare, Menscher said the botnet that launched both attacks bear the fingerprints of Aisuru, a digital siege machine that first surfaced less than a year ago. Menscher said the attack on KrebsOnSecurity lasted less than a minute, hurling large UDP data packets at random ports at a rate of approximately 585 million data packets per second.

“It was the type of attack normally designed to overwhelm network links,” Menscher said, referring to the throughput connections between and among various Internet service providers (ISPs). “For most companies, this size of attack would kill them.”

A graph depicting the 6.5 Tbps attack mitigated by Cloudflare in April 2025. Image: Cloudflare.

The Aisuru botnet comprises a globally-dispersed collection of hacked IoT devices, including routers, digital video recorders and other systems that are commandeered via default passwords or software vulnerabilities. As documented by researchers at QiAnXin XLab, the botnet was first identified in an August 2024 attack on a large gaming platform.

Aisuru reportedly went quiet after that exposure, only to reappear in November with even more firepower and software exploits. In a January 2025 report, XLab found the new and improved Aisuru (a.k.a. “Airashi“) had incorporated a previously unknown zero-day vulnerability in Cambium Networks cnPilot routers.

NOT FORKING AROUND

The people behind the Aisuru botnet have been peddling access to their DDoS machine in public Telegram chat channels that are closely monitored by multiple security firms. In August 2024, the botnet was rented out in subscription tiers ranging from $150 per day to $600 per week, offering attacks of up to two terabits per second.

“You may not attack any measurement walls, healthcare facilities, schools or government sites,” read a notice posted on Telegram by the Aisuru botnet owners in August 2024.

Interested parties were told to contact the Telegram handle “@yfork” to purchase a subscription. The account @yfork previously used the nickname “Forky,” an identity that has been posting to public DDoS-focused Telegram channels since 2021.

According to the FBI, Forky’s DDoS-for-hire domains have been seized in multiple law enforcement operations over the years. Last year, Forky said on Telegram he was selling the domain stresser[.]best, which saw its servers seized by the FBI in 2022 as part of an ongoing international law enforcement effort aimed at diminishing the supply of and demand for DDoS-for-hire services.

“The operator of this service, who calls himself ‘Forky,’ operates a Telegram channel to advertise features and communicate with current and prospective DDoS customers,” reads an FBI seizure warrant (PDF) issued for stresser[.]best. The FBI warrant stated that on the same day the seizures were announced, Forky posted a link to a story on this blog that detailed the domain seizure operation, adding the comment, “We are buying our new domains right now.”

A screenshot from the FBI’s seizure warrant for Forky’s DDoS-for-hire domains shows Forky announcing the resurrection of their service at new domains.

Approximately ten hours later, Forky posted again, including a screenshot of the stresser[.]best user dashboard, instructing customers to use their saved passwords for the old website on the new one.

A review of Forky’s posts to public Telegram channels — as indexed by the cyber intelligence firms Unit 221B and Flashpoint — reveals a 21-year-old individual who claims to reside in Brazil [full disclosure: Flashpoint is currently an advertiser on this blog].

Since late 2022, Forky’s posts have frequently promoted a DDoS mitigation company and ISP that he operates called botshield[.]io. The Botshield website is connected to a business entity registered in the United Kingdom called Botshield LTD, which lists a 21-year-old woman from Sao Paulo, Brazil as the director. Internet routing records indicate Botshield (AS213613) currently controls several hundred Internet addresses that were allocated to the company earlier this year.

Domaintools.com reports that botshield[.]io was registered in July 2022 to a Kaike Southier Leite in Sao Paulo. A LinkedIn profile by the same name says this individual is a network specialist from Brazil who works in “the planning and implementation of robust network infrastructures, with a focus on security, DDoS mitigation, colocation and cloud server services.”

MEET FORKY

Image: Jaclyn Vernace / Shutterstock.com.

In his posts to public Telegram chat channels, Forky has hardly attempted to conceal his whereabouts or identity. In countless chat conversations indexed by Unit 221B, Forky could be seen talking about everyday life in Brazil, often remarking on the extremely low or high prices in Brazil for a range of goods, from computer and networking gear to narcotics and food.

Reached via Telegram, Forky claimed he was “not involved in this type of illegal actions for years now,” and that the project had been taken over by other unspecified developers. Forky initially told KrebsOnSecurity he had been out of the botnet scene for years, only to concede this wasn’t true when presented with public posts on Telegram from late last year that clearly showed otherwise.

Forky denied being involved in the attack on KrebsOnSecurity, but acknowledged that he helped to develop and market the Aisuru botnet. Forky claims he is now merely a staff member for the Aisuru botnet team, and that he stopped running the botnet roughly two months ago after starting a family. Forky also said the woman named as director of Botshield is related to him.

Forky offered equivocal, evasive responses to a number of questions about the Aisuru botnet and his business endeavors. But on one point he was crystal clear:

“I have zero fear about you, the FBI, or Interpol,” Forky said, asserting that he is now almost entirely focused on their hosting business — Botshield.

Forky declined to discuss the makeup of his ISP’s clientele, or to clarify whether Botshield was more of a hosting provider or a DDoS mitigation firm. However, Forky has posted on Telegram about Botshield successfully mitigating large DDoS attacks launched against other DDoS-for-hire services.

DomainTools finds the same Sao Paulo street address in the registration records for botshield[.]io was used to register several other domains, including cant-mitigate[.]us. The email address in the WHOIS records for that domain is forkcontato@gmail.com, which DomainTools says was used to register the domain for the now-defunct DDoS-for-hire service stresser[.]us, one of the domains seized in the FBI’s 2023 crackdown.

On May 8, 2023, the U.S. Department of Justice announced the seizure of stresser[.]us, along with a dozen other domains offering DDoS services. The DOJ said ten of the 13 domains were reincarnations of services that were seized during a prior sweep in December, which targeted 48 top stresser services (also known as “booters”).

Forky claimed he could find out who attacked my site with Aisuru. But when pressed a day later on the question, Forky said he’d come up empty-handed.

“I tried to ask around, all the big guys are not retarded enough to attack you,” Forky explained in an interview on Telegram. “I didn’t have anything to do with it. But you are welcome to write the story and try to put the blame on me.”

THE GHOST OF MIRAI

The 6.3 Tbps attack last week caused no visible disruption to this site, in part because it was so brief — lasting approximately 45 seconds. DDoS attacks of such magnitude and brevity typically are produced when botnet operators wish to test or demonstrate their firepower for the benefit of potential buyers. Indeed, Google’s Menscher said it is likely that both the May 12 attack and the slightly larger 6.5 Tbps attack against Cloudflare last month were simply tests of the same botnet’s capabilities.

In many ways, the threat posed by the Aisuru/Airashi botnet is reminiscent of Mirai, an innovative IoT malware strain that emerged in the summer of 2016 and successfully out-competed virtually all other IoT malware strains in existence at the time.

As first revealed by KrebsOnSecurity in January 2017, the Mirai authors were two U.S. men who co-ran a DDoS mitigation service — even as they were selling far more lucrative DDoS-for-hire services using the most powerful botnet on the planet.

Less than a week after the Mirai botnet was used in a days-long DDoS against KrebsOnSecurity, the Mirai authors published the source code to their botnet so that they would not be the only ones in possession of it in the event of their arrest by federal investigators.

Ironically, the leaking of the Mirai source is precisely what led to the eventual unmasking and arrest of the Mirai authors, who went on to serve probation sentences that required them to consult with FBI investigators on DDoS investigations. But that leak also rapidly led to the creation of dozens of Mirai botnet clones, many of which were harnessed to fuel their own powerful DDoS-for-hire services.

Menscher told KrebsOnSecurity that as counterintuitive as it may sound, the Internet as a whole would probably be better off if the source code for Aisuru became public knowledge. After all, he said, the people behind Aisuru are in constant competition with other IoT botnet operators who are all striving to commandeer a finite number of vulnerable IoT devices globally.

Such a development would almost certainly cause a proliferation of Aisuru botnet clones, he said, but at least then the overall firepower from each individual botnet would be greatly diminished — or at least within range of the mitigation capabilities of most DDoS protection providers.

Barring a source code leak, Menscher said, it would be nice if someone published the full list of software exploits being used by the Aisuru operators to grow their botnet so quickly.

“Part of the reason Mirai was so dangerous was that it effectively took out competing botnets,” he said. “This attack somehow managed to compromise all these boxes that nobody else knows about. Ideally, we’d want to see that fragmented out, so that no [individual botnet operator] controls too much.”