Pierluigi Paganini January 16, 2015

Malware experts at Symantec discovered a new strain of the notorious Carberp Trojan designed to steal banking credentials and sensitive data from victims.

Security experts at Symantec have discovered on December 15 a malicious campaign for distributing of a new strain of the notorious Carberp Trojan.

The continuous evolution of Carberp, exactly like other popular malware inclusing the Zeus Trojan , was made possible by the availability in underground of its source code since June 2013.

The first spam campaign for distributing the new version of the malware, detected as Trojan.Carberp.C, was spotted by Symantec researchers on December 15, just one day after the Trojan was apparently compiled.

The spam email claims to be a payment reminder and includes a malicious attachment that poses as an invoice (e.g. invoice.[RANDOM NUMBERS]_2014.12.11.doc.zip). The Trojan dropper is packed with Visual Basic and it is attached to spam mail as a .ZIP archive file.

Carberp.C, is primarily designed to harvest banking credentials and other sensitive information, but the variant also includes a collection of plugins that are injected into a newly created process (svchost.exe) to implement further features like improved evasion techniques.

“The malware is also able to download additional plugins that are injected into a newly created svchost.exe process in order to keep the infection hidden.” states a blog post published by Symantec on Carberp.C.

One of the plugin examined by the researchers is able to hook APIs to steal sensitive data from the victim’s Web browsers. The new variant appears very effective, it can infect both 32-bit and 64-bit systems and includes plugins for several CPU architectures.

Once the victim opens the ZIP archive, the dropper injects code into a Windows process, and decrypts and decompresses embedded 32-bit or 64-bit modules, depending on the type of operating system.

Once compromised the machine, the Carberp.C variant contacts the command-and-control (C&C) server in order to download additional payloads and load them into memory.

The principal embedded components identified by Symantec researchers in Carberp.C are:

• MyFault—A Windows driver developed by Sysinternals that is normally used to trigger system crashes. This module on its own is not malicious and is used for troubleshooting. But the malware authors may have implemented it in order to trigger a blue screen of death (BSoD) in case the malware is being analyzed.
• Downloader—A silent payload downloader (detected as Trojan.Carberp.C)
• Carberp Driver—Can be used to kill processes and to inject into memory malicious payloads with the aim to hide the infection (detected as Trojan.Carberp.C)

The greatest number of infections for the new strain of Carberp was discovered Australia and United States.

Pierluigi Paganini

(Security Affairs –  Carberp, Trojan)

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