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Win32/Carberp


First posted on 08 November 2011.
Source: SecurityHome

Aliases :

There are no other names known for Win32/Carberp.

Explanation :

Win32/Carberp is a family of trojans that may be delivered via malicious code, for instance by variants of Exploit:JS/Blacole. The trojan downloads other Win32/Carberp components to execute payload code such as stealing online banking credentials and log on data from numerous other software applications, downloading and executing arbitrary files, exporting installed certificates, capturing screen shots and logging keystrokes.
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Win32/Carberp is a family of trojans that may be delivered via malicious code, for instance by variants of Exploit:JS/Blacole. The trojan downloads other Win32/Carberp components to execute payload code such as stealing online banking credentials and log on data from numerous other software applications, downloading and executing arbitrary files, exporting installed certificates, capturing screen shots and logging keystrokes.

Installation
The trojan may be installed by other malicious code such as variants of Exploit:JS/Blacole. It may be written to the following folder as an executable file:

  • %USERPROFILE%\Start Menu\Programs\Startup\< file name> (example: "igfxtray.exe")
The malware utilizes code injection in order to hinder detection and removal. It may inject code into the running process "explorer.exe" and hooks the API "ZwResumeThread" so it will load into a newly created process. Win32/Carberp also hooks the API "ZwQueryDirectoryFile" to hide its dropped file and its configuration file. When the trojan runs at next Windows start, it executes its payload code.

Payload
Downloads other components Win32/Carberp attempts to download the following plug-ins from a remote server:
  • passw.plug - used by the trojan to capture passwords from various applications
  • stopav.plug - used by the trojan to terminate security processes
  • miniav.plug - used by the trojan to remove certain malware


Captures log on credentials
Win32/Carberp uses the plug-in "passw.plug" to capture passwords from the following:

  • Installed software
    • Windows Commander
    • Total Commander
    • FileZilla
    • BProof FTP
    • FTP Commander
    • CuteFTP
    • FlashFXP
    • SmartFTP
    • FFFTP
    • CoffeeCup
    • CoreFTP
    • Frigate3
    • SecureFX
    • UltraFXP
    • FTPRush
    • BitKinex
    • ExpanDrive
    • Classic FTP
    • WinSCP
    • Free FTP
    • LeapFTP
    • WS FTP
    • Cryper Web Site Publisher
    • Far Manager FTP
  • Cached passwords for a shared network resource
  • Credentials stored by Windows protected storage service
  • Log on information for the following communication software and web browsers:
    • Windows Live Messenger
    • Google talk
    • Paltalk
    • QIP Online
    • JAJC
    • Miranda ICQ
    • Yahoo Messenger
    • Outlook
    • Jabber
    • AOL Instant Messenger
    • Camfrog
    • POP Peeper
    • PocoMail
    • Vypress Auvis
    • Group Mail
    • Incredi Mail
    • Mail.Ru
    • Eudora
    • The Bat!
    • Becky! Internet Mail
    • Windows Mail
    • MRA
    • Internet Explorer
    • Safari
    • Firefox
    • Chrome
    • Opera


Disables security software and updates
The trojan uses the plug-in "stopav.plug" to disable the update service of security software associated with vendors and applications in the following list:

  • ArcaVir
  • Avast
  • AVG
  • Avira
  • BitDefender
  • DrWeb
  • ESET NOD32
  • ESET Smart Security
  • McAfee
  • Microsoft Security Essentials
  • Microsoft Security Client
  • Sophos


The malware attempts to exploit a Windows vulnerability (MS08-025) and disable security software by overwriting the memory copy of the System Service Descriptor Table (SSDT).
Note: The vulnerability is corrected by applying Microsoft Security Bulletin MS08-025, released in April 2008.

Removes other malware
Win32/Carberp attempts to remove the following malware families by deleting associated auto-start data and files:

  • Win32/Rbot
  • Win32/EyeStye
  • Win32/Zbot


Steals financial banking log on credentials
Win32/Carberp tries to hook various network related APIs in the web browser process (e.g. "iexplorer.exe", "firefox.exe") to monitor network traffic. The trojan could inject code into webpages from certain websites, or capture credentials for certain online financial services (e.g. PayPal, IBank, Cyberplat and PSB). The trojan attempts to inject its custom code into the webpage returned by the following websites:

  • esk.sbrf.ru
  • online.sberbank.ru
  • *.alfabank.*
  • sbi.sberbank.ru
  • ibank.prbb.ru
  • *telebank.ru


The trojan could redirect log on credentials entered by a consumer to a remote server (for example "alfakinggg.com").

Allows unauthorized access and control
Win32/Carberp attempts to contact a remote server to report its installation and retrieve commands. The server name changes frequently, however some observed server names include:

  • bg78ruhevroujiodjfoir.com
  • fwild.biz
  • huimka.ru
  • sigka.ru
  • tygko.ru


Win32/Carberp attempts to communicate with a remote server to accept commands from a remote attacker. Commands could instruct the trojan to perform the following actions:

  • Update its configuration
  • Download and execute arbitrary files
  • Load other plug-ins or modules
  • Export installed certificates into a cabinet archive file
  • Delete cookies for Internet Explorer and Firefox web browsers
  • Upload captured credentials and certificates to a specified remote server
  • Capture screen shots and log keystrokes, and send the captured data to a specified remote server


Analysis by Shawn Wang

Last update 08 November 2011

 

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