Analysis by: kathleenno
ALIASES:

Trojan:Win32/FakeSysdef (Microsoft); Mal/FakeAV-EA (Sophos)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: No

  • 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.

It deletes the initially executed copy of itself.

  TECHNICAL DETAILS

File Size: 463,360 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 25 May 2011

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:

  • %System Root%\All Users\Application Data\{random filename}.exe

(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)

It creates the following folders:

  • %User Temp%\smtmp
  • %Start Menu%\Programs\{OS Name} Recovery

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003.. %Start Menu% is the current user's Start Menu folder, which is usually C:\Windows\Profiles\{user name}\Start Menu on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Start Menu on Windows NT and C:\Windows\Start Menu or C:\Documents and Settings\{User name}\Start Menu 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
{random file name} = %System Root%\All Users\Application Data\{random file name}.exe

Other System Modifications

This Trojan adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
ActiveDesktop
NoChangingWallpaper = 1

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
Associations
LowRiskFileTypes = /{hq:/s`s:/ogn:/uyu:/dyd:/c`u:/bnl:/ble:/sdf:/lrh:/iul:/iulm:/fhg:/clq:/kqf:/`wh:/lqf:/lqdf:/lnw:/lq2:/l2t:/v`w:/rbs:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
Attachments
SaveZoneInformation = 1

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
System
DisableTaskMgr = 1

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
Explorer
NoDesktop = 1

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\policies\
system
DisableTaskMgr = 1

It modifies the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Download
CheckExeSignatures = no

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
Hidden = 0

(Note: The default value data of the said registry entry is 1.)

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
ShowSuperHidden = 0

(Note: The default value data of the said registry entry is 1.)

Dropping Routine

This Trojan drops the following files:

  • %System Root%\All Users\Application Data\{random filename}.exe - also detected as TROJ_COBRA.HW
  • %Desktop%\{OS Name} Recovery.lnk
  • %Start Menu%\Programs\{OS Name} Recovery\{OS Name} Recovery.lnk
  • %Start Menu%\Programs\{OS Name} Recovery\Uninstall {OS Name} Recovery.lnk

(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.. %Desktop% is the current user's desktop, which is usually C:\Windows\Profiles\{user name}\Desktop on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Desktop on Windows NT, and C:\Documents and Settings\{User Name}\Desktop on Windows 2000, XP, and Server 2003.. %Start Menu% is the current user's Start Menu folder, which is usually C:\Windows\Profiles\{user name}\Start Menu on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Start Menu on Windows NT and C:\Windows\Start Menu or C:\Documents and Settings\{User name}\Start Menu on Windows 2000, XP, and Server 2003.)

Other Details

This Trojan connects to the following possibly malicious URL:

  • {BLOCKED}k.{BLOCKED}k.com
  • {BLOCKED}ad.org
  • {BLOCKED}atonrouge.org
  • {BLOCKED}alaska.org
  • {BLOCKED}ant.org
  • {BLOCKED}ate.org
  • {BLOCKED}been.org
  • {BLOCKED}bowl.org
  • www.{BLOCKED}oastful.org

It deletes the initially executed copy of itself

NOTES:
It moves .LNK files to the created folder %User Temp%\smtmp. It modifies the attributes of files found in the affected system into Hidden, to trick the users that the files have been deleted.