Analysis by: Roland Marco Dela Paz
ALIASES:

Kaspersky : Backdoor.Win32.Gbot.afk; Mcafee : BackDoor-EXI.gen.i

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  TECHNICAL DETAILS

File Size: 159,744 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 17 Mar 2011
Payload: Drops files

Installation

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

  • %User Profile%\Application Data\Microsoft\conhost.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.)

It drops the following non-malicious file:

  • %User Profile%\Application Data\A1B2.580

(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 backdoor adds the following registry entries to enable its automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
conhost = %User Profile%\Application Data\Microsoft\conhost.exe

Other System Modifications

This backdoor adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings
ProxyServer = http=127.0.0.1:{port number}

It modifies the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings
ProxyEnable = 1

(Note: The default value data of the said registry entry is 0.)

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Hardware Profiles\0001\Software\
Microsoft\windows\CurrentVersion\
Internet Settings
ProxyEnable = 1

(Note: The default value data of the said registry entry is 0.)

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Hardware Profiles\Current\Software\
Microsoft\windows\CurrentVersion\
Internet Settings
ProxyEnable = 1

(Note: The default value data of the said registry entry is 0.)

HKEY_CURRENT_CONFIG\Software\Microsoft\
windows\CurrentVersion\Internet Settings
ProxyEnable = 1

(Note: The default value data of the said registry entry is 0.)

  SOLUTION

Minimum Scan Engine: 8.900
VSAPI OPR PATTERN File: 7.909.00
VSAPI OPR PATTERN Date: 17 Mar 2011

NOTES:

Trend customers:

    Keep your pattern and scan engine files updated. Trend Micro antivirus software can clean or remove most types of computer threats. Malware, though, such as Trojans, scripts, overwriting viruses and joke programs which are identified as uncleanable, should simply be deleted.

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