ALIASES:

Trojan:Win32/Startpage.gen!A (Microsoft); :W32/Autorun.worm!nk (McAfee); Trojan.Gen (Symantec); Trojan.Win32.Swisyn.cadz (Kaspersky); Trojan.Win32.Generic!BT (Sunbelt); Gen:Variant.Graftor.3049 (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.

  TECHNICAL DETAILS

File Size: 147,456 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 15 Jan 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\
Windows\CurrentVersion\Run
alg = "%Program Files%\Common Files\alg.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
smss = "%Program Files%\Common Files\smss.exe"

Other System Modifications

This Trojan deletes the following files:

  • %Windows%\VC.ini

(Note: %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.)

Dropping Routine

This Trojan drops the following files:

  • %Program Files%\Common Files\alg.exe
  • %Program Files%\Common Files\smss.exe
  • %Program Files%\..\usp10.dll
  • %Program Files%\..\explorer.exe
  • %Program Files%\Common Files\tb.ico
  • %Program Files%\Adobe\usp10.dll
  • %Program Files%\Common Files\xs.ico
  • %Program Files%\Adobe\explorer.exe
  • %Program Files%\Common Files\xyx.ico
  • %Program Files%\Common Files\xz.ico
  • %Program Files%\Common Files\usp10.dll
  • %Program Files%\Common Files\dy.ico
  • %Program Files%\Common Files\explorer.exe
  • %Program Files%\ComPlus Applications\usp10.dll
  • %Program Files%\ComPlus Applications\explorer.exe
  • %Program Files%\Internet Explorer\usp10.dll
  • %Program Files%\Internet Explorer\explorer.exe
  • %Program Files%\Messenger\usp10.dll
  • %Program Files%\Messenger\explorer.exe
  • %Program Files%\microsoft frontpage\usp10.dll
  • %Program Files%\microsoft frontpage\explorer.exe
  • %Program Files%\Microsoft.NET\usp10.dll
  • %Program Files%\Microsoft.NET\explorer.exe
  • %Program Files%\Movie Maker\usp10.dll
  • %Program Files%\Movie Maker\explorer.exe
  • %Program Files%\MSBuild\usp10.dll
  • %Program Files%\MSBuild\explorer.exe
  • %Program Files%\MSN\usp10.dll
  • %Program Files%\MSN\explorer.exe
  • %Program Files%\MSN Gaming Zone\usp10.dll
  • %Program Files%\MSN Gaming Zone\explorer.exe
  • %Program Files%\MSXML 6.0\usp10.dll
  • %Program Files%\MSXML 6.0\explorer.exe
  • %Program Files%\NetMeeting\usp10.dll
  • %Program Files%\NetMeeting\explorer.exe
  • %Program Files%\Online Services\usp10.dll
  • %Program Files%\Online Services\explorer.exe
  • %Program Files%\Outlook Express\usp10.dll
  • %Program Files%\Outlook Express\explorer.exe
  • %Program Files%\Reference Assemblies\usp10.dll
  • %Program Files%\Reference Assemblies\explorer.exe
  • %Program Files%\Uninstall Information\usp10.dll
  • %Program Files%\Uninstall Information\explorer.exe
  • %Program Files%\Windows Media Player\usp10.dll
  • %Program Files%\Windows Media Player\explorer.exe
  • %Program Files%\Windows NT\usp10.dll
  • %Program Files%\Windows NT\explorer.exe
  • %Program Files%\WindowsUpdate\usp10.dll
  • %Program Files%\WindowsUpdate\explorer.exe
  • %Program Files%\WinPcap\usp10.dll
  • %Program Files%\WinPcap\explorer.exe
  • %Program Files%\xerox\usp10.dll
  • %Program Files%\xerox\explorer.exe
  • %Windows%\VC.ini

(Note: %Program Files% is the default Program Files folder, usually C:\Program Files.. %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.)

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

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\Windows\CurrentVersion\Run
    • alg="%Program Files%\Common Files\alg.exe"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • smss="%Program Files%\Common Files\smss.exe"

Step 4

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.
  • %Program Files%\Common Files\alg.exe
  • %Program Files%\Common Files\smss.exe
  • %Program Files%\..\usp10.dll
  • %Program Files%\..\explorer.exe
  • %Program Files%\Common Files\tb.ico
  • %Program Files%\Adobe\usp10.dll
  • %Program Files%\Common Files\xs.ico
  • %Program Files%\Adobe\explorer.exe
  • %Program Files%\Common Files\xyx.ico
  • %Program Files%\Common Files\xz.ico
  • %Program Files%\Common Files\usp10.dll
  • %Program Files%\Common Files\dy.ico
  • %Program Files%\Common Files\explorer.exe
  • %Program Files%\ComPlus Applications\usp10.dll
  • %Program Files%\ComPlus Applications\explorer.exe
  • %Program Files%\Internet Explorer\usp10.dll
  • %Program Files%\Internet Explorer\explorer.exe
  • %Program Files%\Messenger\usp10.dll
  • %Program Files%\Messenger\explorer.exe
  • %Program Files%\microsoft frontpage\usp10.dll
  • %Program Files%\microsoft frontpage\explorer.exe
  • %Program Files%\Microsoft.NET\usp10.dll
  • %Program Files%\Microsoft.NET\explorer.exe
  • %Program Files%\Movie Maker\usp10.dll
  • %Program Files%\Movie Maker\explorer.exe
  • %Program Files%\MSBuild\usp10.dll
  • %Program Files%\MSBuild\explorer.exe
  • %Program Files%\MSN\usp10.dll
  • %Program Files%\MSN\explorer.exe
  • %Program Files%\MSN Gaming Zone\usp10.dll
  • %Program Files%\MSN Gaming Zone\explorer.exe
  • %Program Files%\MSXML 6.0\usp10.dll
  • %Program Files%\MSXML 6.0\explorer.exe
  • %Program Files%\NetMeeting\usp10.dll
  • %Program Files%\NetMeeting\explorer.exe
  • %Program Files%\Online Services\usp10.dll
  • %Program Files%\Online Services\explorer.exe
  • %Program Files%\Outlook Express\usp10.dll
  • %Program Files%\Outlook Express\explorer.exe
  • %Program Files%\Reference Assemblies\usp10.dll
  • %Program Files%\Reference Assemblies\explorer.exe
  • %Program Files%\Uninstall Information\usp10.dll
  • %Program Files%\Uninstall Information\explorer.exe
  • %Program Files%\Windows Media Player\usp10.dll
  • %Program Files%\Windows Media Player\explorer.exe
  • %Program Files%\Windows NT\usp10.dll
  • %Program Files%\Windows NT\explorer.exe
  • %Program Files%\WindowsUpdate\usp10.dll
  • %Program Files%\WindowsUpdate\explorer.exe
  • %Program Files%\WinPcap\usp10.dll
  • %Program Files%\WinPcap\explorer.exe
  • %Program Files%\xerox\usp10.dll
  • %Program Files%\xerox\explorer.exe
  • %Windows%\VC.ini

Step 5

Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_SWISYN.KQ. 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 6

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. %Windows%\VC.ini


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