Posts Tagged: p2p botnet

Jun 14

‘Operation Tovar’ Targets ‘Gameover’ ZeuS Botnet, CryptoLocker Scourge

The U.S. Justice Department is expected to announce today an international law enforcement operation to seize control over the Gameover ZeuS botnet, a sprawling network of hacked Microsoft Windows computers that currently infects an estimated 500,000 to 1 million compromised systems globally. Experts say PCs infected with Gameover are being harvested for sensitive financial and personal data, and rented out to an elite cadre of hackers for use in online extortion attacks, spam and other illicit moneymaking schemes.

This graphic, from 2012, shows the decentralized nature of P2P network connectivity of 23,196 PCs infected with Gameover.  Image: Dell SecureWorks

This graphic, from 2012, shows the decentralized nature of P2P network connectivity of 23,196 PCs infected with Gameover. Image: Dell SecureWorks

The sneak attack on Gameover, dubbed “Operation Tovar,” began late last week and is a collaborative effort by investigators at the FBI, Europol, and the UK’s National Crime Agency; security firms CrowdStrike, Dell SecureWorks, SymantecTrend Micro and McAfee; and academic researchers at VU University Amsterdam and Saarland University in Germany. News of the action first came to light in a blog post published briefly on Friday by McAfee, but that post was removed a few hours after it went online.

Gameover is based on code from the ZeuS Trojan, an infamous family of malware that has been used in countless online banking heists. Unlike ZeuS — which was sold as a botnet creation kit to anyone who had a few thousand dollars in virtual currency to spend — Gameover ZeuS has since October 2011 been controlled and maintained by a core group of hackers from Russia and Ukraine.

Those individuals are believed to have used the botnet in high-dollar corporate account takeovers that frequently were punctuated by massive distributed-denial-of-service (DDoS) attacks intended to distract victims from immediately noticing the thefts. According to the Justice Department, Gameover has been implicated in the theft of more than $100 million in account takeovers.

The curators of Gameover also have reportedly loaned out sections of their botnet to vetted third-parties who have used them for a variety of purposes. One of the most popular uses of Gameover has been as a platform for seeding infected systems with CryptoLocker, a nasty strain of malware that locks your most precious files with strong encryption until you pay a ransom demand.

According to a 2012 research paper published by Dell SecureWorks, the Gameover Trojan is principally spread via Cutwail, one of the world’s largest and most notorious spam botnets (for more on Cutwail and its origins and authors, see this post). These junk emails typically spoof trusted brands, including shipping and phone companies, online retailers, social networking sites and financial institutions. The email lures bearing Gameover often come in the form of an invoice, an order confirmation, or a warning about an unpaid bill (usually with a large balance due to increase the likelihood that a victim will click the link). The links in the email have been replaced with those of compromised sites that will silently probe the visitor’s browser for outdated plugins that can be leveraged to install malware.

It will be interesting to hear how the authorities and security researchers involved in this effort managed to gain control over the Gameover botnet, which uses an advanced peer-to-peer (P2P) mechanism to control and update the bot-infected systems. Continue reading →

Dec 13

ZeroAccess Botnet Down, But Not Out

Europol, Microsoft Kneecap Click-Fraud Botnet

Authorities in Europe joined Microsoft Corp. this week in disrupting “ZeroAccess,” a vast botnet that has enslaved more than two million PCs with malicious software in an elaborate and lucrative scheme to defraud online advertisers.

The action comes partly from Europol’s European Cybercrime Center (EC3), as well as law enforcement cybercrime units from Germany, Latvia, Switzerland and the Netherlands, countries that hosted many of the Internet servers used to control the ZeroAccess botnet.

In tandem with the law enforcement moves in Europe, Microsoft filed a civil lawsuit to unmask eight separate cybercriminals thought to be operating the giant botnet, and to block incoming and outgoing communications between infected PCs in the United States and those 18 control servers, according to a statement released by EC3.

The malware the powers the botnet, also known as “ZAccess” and “Sirefef,” is a complex threat that has evolved significantly since its inception in 2009. It began as a malware delivery platform that was used to spread other threats, such as fake antivirus software (a.k.a. “scareware”).

In recent years, however, the miscreants behind ZeroAccess rearchitected the botnet so that infected systems were forced to perpetrate a moneymaking scheme known as “click fraud” — the practice of fraudulently generating clicks on ads without any intention of fruitfully interacting with the advertiser’s site.

Maps of ZeroAccess infected PCs in Texas. Source:

Maps of ZeroAccess infected PCs in Texas. Source:

It remains unclear how much this coordinated action will impact the operations of ZeroAccess over the long term. Early versions of ZeroAccess relied on a series of control servers to receive updates, but recent versions of the botnet malware were designed to make the network as a whole more resilient and resistant to targeted takedowns such as the one executed this week.

Specifically, ZeroAccess employs a peer-to-peer (P2P) architecture in which new instructions and payloads are distributed from one infected host to another. P2P-based botnets are designed to eliminate a single point of failure, so that if one node used to control the botnet is knocked offline, the remainder of the botnet can still function.

The actions this week appear to have targeted the servers that deliver a specific component of ZeroAccess that gives infected systems new instructions on how to defraud various online advertisers — including Microsoft. While this effort will not disable the ZeroAccess botnet (the infected systems will likely remain infected), it should allow Microsoft to determine which online affiliates and publishers are associated with the miscreants behind ZeroAccess, since those publishers will have stopped sending traffic directly after the takedown occurred.

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