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TROJ_CUTWAIL.LM

April 09, 2013
 Analysis by: Rika Joi Gregorio
 ALIASES:

TrojanDownloader:Win32/Cutwail.BS(Microsoft), Trojan-Downloader.Win32.Cutwail(Ikarus)

 PLATFORM:

Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW


This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

  TECHNICAL DETAILS

File Size:

41,472 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

23 Mar 2013

Arrival Details

This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

Installation

This Trojan drops the following copies of itself into the affected system:

  • %User Profile%\nobfudycomal.exe

(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.)

Autostart Technique

This Trojan adds the following registry entries to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
nobfudycomal = "%User Profile%\nobfudycomal.exe"

Other System Modifications

This Trojan adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion
AppManagement = "{random value}"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion
nobfudycomalzap = "{random value}"

HKEY_CURRENT_USER\Software\WinRAR
HWID = "{random value}"