TROJ_VUNDO.GJ


 ALIASES:

Trojan:Win32/Relbma.A (Microsoft); Generic Downloader.x (McAfee); Trojan.Vundo (Symantec); Trojan-Spy.Win32.Amber.mb (Kaspersky); Trojan-Downloader.Win32.FraudLoad.vcqa (Sunbelt); Trojan-Spy:W32/Ambler.gen!B (FSecure)

 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

  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 itself after execution.

  TECHNICAL DETAILS

File Size:

60,928 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

16 Apr 2012

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.

Autostart Technique

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Active Setup\Installed Components\{A744F16C-B2D5-4138-81A2-085CDFCDE83A}
Locale = "EN"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Active Setup\Installed Components\{A744F16C-B2D5-4138-81A2-085CDFCDE83A}
StubPath = "rundll32 sxmg4.dll,InitModule"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Active Setup\Installed Components\{A744F16C-B2D5-4138-81A2-085CDFCDE83A}
IsInstalled = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Active Setup\Installed Components\{A744F16C-B2D5-4138-81A2-085CDFCDE83A}
Version = "1,0,0,2"

It registers itself as a BHO to ensure its automatic execution every time Internet Explorer is used by adding the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Explorer\
Browser Helper Objects\{32C620D6-CC10-4e6a-9715-BACACD5B0E61}

Other System Modifications

This Trojan deletes the following files:

  • %System%\lt.res

(Note: %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.)

It adds the following registry keys:

HKEY_LOCAL_MACHINE\Software\TSoft

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Browser Helper Objects

HKEY_CLASSES_ROOT\CLSID\{32C620D6-CC10-4e6a-9715-BACACD5B0E61}

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{32C620D6-CC10-4e6a-9715-BACACD5B0E61}\InprocServer32

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{32C620D6-CC10-4e6a-9715-BACACD5B0E61}\ProgID

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{32C620D6-CC10-4e6a-9715-BACACD5B0E61}\TypeLib

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Active Setup\Installed Components\{A744F16C-B2D5-4138-81A2-085CDFCDE83A}

HKEY_CLASSES_ROOT\CLSID\{A744F16C-B2D5-4138-81A2-085CDFCDE83A}

HKEY_CLASSES_ROOT\CLSID\{A744F16C-B2D5-4138-81A2-085CDFCDE83A}\
InProcServer32

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Main\FeatureControl\
FEATURE_LOCALMACHINE_LOCKDOWN

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\TSoft
MainM = "XSFL_CHAR(0x1F)__CHAR(0x05)_OGG"

HKEY_LOCAL_MACHINE\SOFTWARE\TSoft
NUM = "l$%T!%'S!:TT&':#r!v:. &:UVTVTSU'R!&j"

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{32C620D6-CC10-4e6a-9715-BACACD5B0E61}\InprocServer32
ThreadingModel = "Apartment"

HKEY_LOCAL_MACHINE\SOFTWARE\TSoft
Ad = "{random values}"

HKEY_LOCAL_MACHINE\SOFTWARE\TSoft
NN = "{random values}"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\ShellServiceObjectDelayLoad
WebProxy = "{A744F16C-B2D5-4138-81A2-085CDFCDE83A}"

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{A744F16C-B2D5-4138-81A2-085CDFCDE83A}\InProcServer32
ThreadingModel = "Apartment"

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Main\FeatureControl\
FEATURE_LOCALMACHINE_LOCKDOWN
iexplore.exe = "0"

Dropping Routine

This Trojan drops the following files:

  • %System%\sxmg4.dll
  • %System%\sft.res

(Note: %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.)

Other Details

This Trojan deletes itself after execution.

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine:

9.200

Step 1

For Windows XP and Windows Server 2003 users, before doing any scans, please make sure you disable System Restore to allow full scanning of your computer.

Step 2

Restart in Safe Mode

[ Learn More ]

Step 3

Close all opened browser windows

Step 4

Delete this registry key

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

  • In HKEY_LOCAL_MACHINE\Software
    • TSoft
  • In HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Explorer
    • Browser Helper Objects
  • In HKEY_CLASSES_ROOT\CLSID
    • {32C620D6-CC10-4e6a-9715-BACACD5B0E61}
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{32C620D6-CC10-4e6a-9715-BACACD5B0E61}
    • InprocServer32
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{32C620D6-CC10-4e6a-9715-BACACD5B0E61}
    • ProgID
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{32C620D6-CC10-4e6a-9715-BACACD5B0E61}
    • TypeLib
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Active Setup\Installed Components
    • {A744F16C-B2D5-4138-81A2-085CDFCDE83A}
  • In HKEY_CLASSES_ROOT\CLSID
    • {A744F16C-B2D5-4138-81A2-085CDFCDE83A}
  • In HKEY_CLASSES_ROOT\CLSID\{A744F16C-B2D5-4138-81A2-085CDFCDE83A}
    • InProcServer32
  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main\FeatureControl
    • FEATURE_LOCALMACHINE_LOCKDOWN

Step 5

Delete this registry value

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Active Setup\Installed Components\{A744F16C-B2D5-4138-81A2-085CDFCDE83A}
    • Locale = "EN"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Active Setup\Installed Components\{A744F16C-B2D5-4138-81A2-085CDFCDE83A}
    • StubPath = "rundll32 sxmg4.dll,InitModule"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Active Setup\Installed Components\{A744F16C-B2D5-4138-81A2-085CDFCDE83A}
    • IsInstalled = "1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Active Setup\Installed Components\{A744F16C-B2D5-4138-81A2-085CDFCDE83A}
    • Version = "1,0,0,2"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\TSoft
    • MainM = "XSFL_CHAR(0x1F)__CHAR(0x05)_OGG"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\TSoft
    • NUM = "l$%T!%'S!:TT&':#r!v:. &:UVTVTSU'R!&j"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{32C620D6-CC10-4e6a-9715-BACACD5B0E61}\InprocServer32
    • ThreadingModel = "Apartment"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\TSoft
    • Ad = "{random values}"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\TSoft
    • NN = "{random values}"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\ShellServiceObjectDelayLoad
    • WebProxy = "{A744F16C-B2D5-4138-81A2-085CDFCDE83A}"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{A744F16C-B2D5-4138-81A2-085CDFCDE83A}\InProcServer32
    • ThreadingModel = "Apartment"
  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main\FeatureControl\FEATURE_LOCALMACHINE_LOCKDOWN
    • iexplore.exe = "0"

Step 6

Search and delete these files

[ Learn More ]
There may be some component files that are hidden. Please make sure you check the Search Hidden Files and Folders checkbox in the "More advanced options" option to include all hidden files and folders in the search result.
  • %System%\sxmg4.dll
  • %System%\sft.res

Step 7

Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_VUNDO.GJ. If the detected files have already been cleaned, deleted, or quarantined by your Trend Micro product, no further step is required. You may opt to simply delete the quarantined files. Please check this Knowledge Base page for more information.

Step 8

Restore this file from backup only Microsoft-related files will be restored. If this malware/grayware also deleted files related to programs that are not from Microsoft, please reinstall those programs on you computer again.

  • %System%\lt.res


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