Analysis by: Sabrina Lei Sioting
ALIASES:

Trojan.Win32.Pakes.bro (Kaspersky), Trojan.Dropper (Symantec), TR/Dropper.Gen (Avira), Mal/Generic-A (Sophos), Spammer:Win32/Tedroo.B (Microsoft)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  TECHNICAL DETAILS

File Size: 97,792 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 18 May 2011

Installation

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

  • %User Profile%\Application Data\xmzcaxyizutkp1ubgplblsveocf1jcog2\svcnost.exe

(Note: %User Profile% is the current user's profile folder, which is usually C:\Windows\Profiles\{user name} on Windows 98 and ME, C:\WINNT\Profiles\{user name} on Windows NT, and C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003.)

It creates the following folders:

  • %User Profile%\Application Data\xmzcaxyizutkp1ubgplblsveocf1jcog2

(Note: %User Profile% is the current user's profile folder, which is usually C:\Windows\Profiles\{user name} on Windows 98 and ME, C:\WINNT\Profiles\{user name} on Windows NT, and C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003.)

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
mssend = "%User Profile%\Application Data\xmzcaxyizutkp1ubgplblsveocf1jcog2\svcnost.exe"

Other System Modifications

This Trojan creates the following registry entry(ies) to bypass Windows Firewall:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\AuthorizedApplications\
List
%User Profile%\Application Data\xmzcaxyizutkp1ubgplblsveocf1jcog2\svcnost.exe = "%User Profile%\Application Data\xmzcaxyizutkp1ubgplblsveocf1jcog2\svcnost.exe:*:Enabled:ldrsoft"