Treasury Sanctions Creators of 911 S5 Proxy Botnet

The U.S. Department of the Treasury today unveiled sanctions against three Chinese nationals for allegedly operating 911 S5, an online anonymity service that for many years was the easiest and cheapest way to route one’s Web traffic through malware-infected computers around the globe. KrebsOnSecurity identified one of the three men in a July 2022 investigation into 911 S5, which was massively hacked and then closed ten days later.

From 2015 to July 2022, 911 S5 sold access to hundreds of thousands of Microsoft Windows computers daily, as “proxies” that allowed customers to route their Internet traffic through PCs in virtually any country or city around the globe — but predominantly in the United States.

911 built its proxy network mainly by offering “free” virtual private networking (VPN) services. 911’s VPN performed largely as advertised for the user — allowing them to surf the web anonymously — but it also quietly turned the user’s computer into a traffic relay for paying 911 S5 customers.

911 S5’s reliability and extremely low prices quickly made it one of the most popular services among denizens of the cybercrime underground, and the service became almost shorthand for connecting to that “last mile” of cybercrime. Namely, the ability to route one’s malicious traffic through a computer that is geographically close to the consumer whose stolen credit card is about to be used, or whose bank account is about to be emptied.

In July 2022, KrebsOnSecurity published a deep dive into 911 S5, which found the people operating this business had a history of encouraging the installation of their proxy malware by any means available. That included paying affiliates to distribute their proxy software by secretly bundling it with other software.

That story named Yunhe Wang from Beijing as the apparent owner or manager of the 911 S5 proxy service. In today’s Treasury action, Mr. Wang was named as the primary administrator of the botnet that powered 911 S5.

“A review of records from network infrastructure service providers known to be utilized by 911 S5 and two Virtual Private Networks (VPNs) specific to the botnet operation (MaskVPN and DewVPN) showed Yunhe Wang as the registered subscriber to those providers’ services,” reads the Treasury announcement.

Update, May 29, 12:26 p.m. ET: The U.S. Department of Justice (DOJ) just announced they have arrested Wang in connection with the 911 S5 botnet. The DOJ says 911 S5 customers have stolen billions of dollars from financial institutions, credit card issuers, and federal lending programs.

“911 S5 customers allegedly targeted certain pandemic relief programs,” a DOJ statement on the arrest reads. “For example, the United States estimates that 560,000 fraudulent unemployment insurance claims originated from compromised IP addresses, resulting in a confirmed fraudulent loss exceeding $5.9 billion. Additionally, in evaluating suspected fraud loss to the Economic Injury Disaster Loan (EIDL) program, the United States estimates that more than 47,000 EIDL applications originated from IP addresses compromised by 911 S5. Millions of dollars more were similarly identified by financial institutions in the United States as loss originating from IP addresses compromised by 911 S5.”

The sanctions say Jingping Liu was Yunhe Wang’s co-conspirator in the laundering of criminally derived proceeds generated from 911 S5, mainly virtual currency. The government alleges the virtual currencies paid by 911 S5 users were converted into U.S. dollars using over-the-counter vendors who wired and deposited funds into bank accounts held by Liu.

“Jingping Liu assisted Yunhe Wang by laundering criminally derived proceeds through bank accounts held in her name that were then utilized to purchase luxury real estate properties for Yunhe Wang,” the document continues. “These individuals leveraged their malicious botnet technology to compromise personal devices, enabling cybercriminals to fraudulently secure economic assistance intended for those in need and to terrorize our citizens with bomb threats.”

The third man sanctioned is Yanni Zheng, a Chinese national the U.S. Treasury says acted as an attorney for Wang and his firm — Spicy Code Company Limited — and helped to launder proceeds from the business into real estate holdings. Spicy Code Company was also sanctioned, as well as Wang-controlled properties Tulip Biz Pattaya Group Company Limited, and Lily Suites Company Limited.

Ten days after the July 2022 story here on 911 S5, the proxy network abruptly closed up shop, citing a data breach that destroyed key components of its business operations.

In the months that followed, however, 911 S5 would resurrect itself under a different name: Cloud Router. That’s according to spur.us, a U.S.-based startup that tracks proxy and VPN services. In February 2024, Spur published research showing the Cloud Router operators reused many of the same components from 911 S5, making it relatively simple to draw a connection between the two.

Spur found that Cloud Router was being powered by a new VPN service called PaladinVPN, which made it much more explicit to users that their Internet connections were going to be used to relay traffic for others. At the time, Spur found Cloud Router had more than 140,000 Internet addresses for rent.

Spur co-founder Riley Kilmer said Cloud Router appears to have suspended or ceased operations sometime this past weekend. Kilmer said the number of proxies advertised by the service had been trending downwards quite recently before the website suddenly went offline.

Cloud Router’s homepage is currently populated by a message from Cloudflare saying the site’s domain name servers are pointing to a “prohibited IP.”

Malicious Apps Caught Secretly Turning Android Phones into Proxies for Cybercriminals

Several malicious Android apps that turn mobile devices running the operating system into residential proxies (RESIPs) for other threat actors have been observed on the Google Play Store. The findings come from HUMAN's Satori Threat Intelligence team, which said the cluster of VPN apps came fitted with a Golang library that transformed the user's device into a proxy node without their knowledge.

911 Proxy Service Implodes After Disclosing Breach

911[.]re, a proxy service that since 2015 has sold access to hundreds of thousands of Microsoft Windows computers daily, announced this week that it is shutting down in the wake of a data breach that destroyed key components of its business operations. The abrupt closure comes ten days after KrebsOnSecurity published an in-depth look at 911 and its connections to shady pay-per-install affiliate programs that secretly bundled 911’s proxy software with other titles, including “free” utilities and pirated software.

911[.]re is was one of the original “residential proxy” networks, which allow someone to rent a residential IP address to use as a relay for his/her Internet communications, providing anonymity and the advantage of being perceived as a residential user surfing the web.

Residential proxy services are often marketed to people seeking the ability to evade country-specific blocking by the major movie and media streaming providers. But some of them — like 911 — build their networks in part by offering “free VPN” or “free proxy” services that are powered by software which turns the user’s PC into a traffic relay for other users. In this scenario, users indeed get to use a free VPN service, but they are often unaware that doing so will turn their computer into a proxy that lets others use their Internet address to transact online.

From a website’s perspective, the IP traffic of a residential proxy network user appears to originate from the rented residential IP address, not from the proxy service customer. These services can be used in a legitimate manner for several business purposes — such as price comparisons or sales intelligence — but they are massively abused for hiding cybercrime activity because they can make it difficult to trace malicious traffic to its original source.

As noted in KrebsOnSecurity’s July 19 story on 911, the proxy service operated multiple pay-per-install schemes that paid affiliates to surreptitiously bundle the proxy software with other software, continuously generating a steady stream of new proxies for the service.

Within hours of that story, 911 posted a notice at the top of its site, saying, “We are reviewing our network and adding a series of security measures to prevent misuse of our services. Proxy balance top-up and new user registration are closed. We are reviewing every existing user, to ensure their usage is legit and [in] compliance with our Terms of Service.”

At this announcement, all hell broke loose on various cybercrime forums, where many longtime 911 customers reported they were unable to use the service. Others affected by the outage said it seemed 911 was trying to implement some sort of “know your customer” rules — that maybe 911 was just trying to weed out those customers using the service for high volumes of cybercriminal activity.

Then on July 28, the 911 website began redirecting to a notice saying, “We regret to inform you that we permanently shut down 911 and all its services on July 28th.”

According to 911, the service was hacked in early July, and it was discovered that someone manipulated the balances of a large number of user accounts. 911 said the intruders abused an application programming interface (API) that handles the topping up of accounts when users make financial deposits with the service.

“Not sure how did the hacker get in,” the 911 message reads. “Therefore, we urgently shut down the recharge system, new user registration, and an investigation started.”

However the intruders got in, 911 said, they managed to also overwrite critical 911[.]re servers, data and backups of that data.

“On July 28th, a large number of users reported that they could not log in the system,” the statement continues. “We found that the data on the server was maliciously damaged by the hacker, resulting in the loss of data and backups. Its [sic] confirmed that the recharge system was also hacked the same way. We were forced to make this difficult decision due to the loss of important data that made the service unrecoverable.”

Operated largely out of China, 911 was an enormously popular service across many cybercrime forums, and it became something akin to critical infrastructure for this community after two of 911’s longtime competitors — malware-based proxy services VIP72 and LuxSocks — closed their doors in the past year.

Now, many on the crime forums who relied on 911 for their operations are wondering aloud whether there are any alternatives that match the scale and utility that 911 offered. The consensus seems to be a resounding “no.”

I’m guessing we may soon learn more about the security incidents that caused 911 to implode. And perhaps other proxy services will spring up to meet what appears to be a burgeoning demand for such services at the moment, with comparatively little supply.

In the meantime, 911’s absence may coincide with a measurable (if only short-lived) reprieve in unwanted traffic to top Internet destinations, including banks, retailers and cryptocurrency platforms, as many former customers of the proxy service scramble to make alternative arrangements.

Riley Kilmer, co-founder of the proxy-tracking service Spur.us, said 911’s network will be difficult to replicate in the short run.

“My speculation is [911’s remaining competitors] are going to get a major boost in the short term, but a new player will eventually come along,” Kilmer said. “None of those are good replacements for LuxSocks or 911. However, they will all allow anyone to use them. For fraud rates, the attempts will continue but through these replacement services which should be easier to monitor and stop. 911 had some very clean IP addresses.”

911 wasn’t the only major proxy provider disclosing a breach this week tied to unauthenticated APIs: On July 28, KrebsOnSecurity reported that internal APIs exposed to the web had leaked the customer database for Microleaves, a proxy service that rotates its customers’ IP addresses every five to ten minutes. That investigation showed Microleaves — like 911 — had a long history of using pay-per-install schemes to spread its proxy software.