TROJ_MALAGENT.GZ

 Analysis by: Kathleen Notario

 PLATFORM:

Windows 2000, XP, 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:

119,296 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

13 Aug 2010

Other System Modifications

This Trojan adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
EnableConcurrentSessions = 1

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Control\Terminal Server\Licensing Core
EnableConcurrentSessions = 1

Dropping Routine

This Trojan drops the following files:

  • %Windows%\host32.exe - detected as TROJ_DROPPR.SMH

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

  SOLUTION

Minimum Scan Engine:

8.900

VSAPI OPR PATTERN File:

7.380.06

VSAPI OPR PATTERN Date:

13 Aug 2010

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

Remove malware files dropped/downloaded by TROJ_MALAGENT.GZ

    TROJ_DROPPR.SMH

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 NT\CurrentVersion\Winlogon
    • EnableConcurrentSessions=1
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Terminal Server\Licensing Core
    • EnableConcurrentSessions=1

Step 4

Restore this modified 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 NT\CurrentVersion\Winlogon
    • From: Userinit=%System%\userinit.exe, %Windows%\host32.exe,
      To: %System%\userinit.exe,
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
    • From: AllowMultipleTSSessions=1
      To: 0
  • In HKEY_LOCAL_MACHINES\SYSTEM\CurrentControlSet\Control\TerminalServer
    • From: fDenyTSConnections=0
      To: 1

Step 5

Scan your computer with your Trend Micro product to delete files detected as TROJ_MALAGENT.GZ. 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.


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