The source code for “Carberp” — a botnet creation kit coded by a team of at least two dozen hackers who used it to relieve banks of an estimated $250 million — has been posted online for anyone to download. The code leak offers security experts a fascinating and somewhat rare glimpse into the malcoding economy, but many also worry that its publication will spawn new hybrid strains of sophisticated banking malware.
The leak appears to have begun, as these things often do, with the sale of the source code in a semi-private cybercrime forum. On June 5, a member of the Lampeduza crime forum said he was selling the Carberp source to a single buyer, with a starting price of $25,000. The seller said he was helping out one of the developers of the code, who was short on cash.
By mid-June, links to download the entire Carberp archive were being posted on multiple forums, as first documented by Trusteer. Since then, experts from around the world have been tearing through the two-gigabyte archive to learn more about the code and its potential for future abuse in new and existing malware creations.
“Leaking the source code was not like the leaking of a weapon, but more like the leaking of a tank factory,” wrote one Ukrainian tech blogger on Livejournal.
According to Peter Kruse, a specialist with the Copenhagen-based CSIS Security Group, the package includes the Carberp bootkit; this is a component that can subvert the Patchguard protection in Windows 7 x86 and 64-bit systems so that the malware loads itself at the most basic levels of the system (Kruse said the bootkit component is incomplete and does not work against Windows 8 PCs).
Also included are components of a Trojan known as UrSnif, as well as an extremely popular and prevalent rival botnet creation kit called Citadel.
“As with the leakage of the ZeuS source code, back in May 2011, this means that criminals have every chance to modify and even add new features to the kit,” Kruse wrote, noting that the Carberp archive also contains several text files that appear to be records of private chats and various usernames and passwords.
Last year, Russian and Ukrainian authorities arrested a loosely-affiliated group of hackers accused of programming and using Carberp to rob millions from bank accounts of their countrymen. According to an account of the law enforcement action in the Russian news outlet Kommersant, Carberp was coded by a team of about 20-25 people under the age of 30. Most of the men had never met face-to-face. Each worked remotely and was responsible for developing specific modules of the Carberp code, components that were then transmitted to a main development server in Odessa, Ukraine.
Members of the coding forum kernelmode.info have been poring over comments left in the code by the Carberp developers. One set of comments, translated from Russian by a KrebsOnSecurity reader, suggests the developer was frustrated by having to program within the confines of what he considered sloppy operating system or perhaps Web browser plugin code.
“I will rip off someone’s hands for this kind of code!” the unidentified developer noted in one section of the Carberp source. “This stupid thing does God-knows-what.”