Analysis by: Kathleen Notario
 PLATFORM:

Windows 2000, XP, Server 2003

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

This backdoor may be dropped by other malware.

  TECHNICAL DETAILS

File Size: Varies
File Type: PE
Memory Resident: Yes
Initial Samples Received Date: 22 Dec 2010
Payload: Compromises system security, Connects to URLs/Ips

Arrival Details

This backdoor may be dropped by the following malware:

  • TROJ_TARODROP.M

Installation

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

  • %System%\WudfSvc.exe

(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.)

Autostart Technique

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\policies\
Explorer\Run
WudfSvc = %System%\WudfSvc.exe

Dropping Routine

This backdoor drops the following files:

  • %System%\fixmapi.dll - also detected as BKDR_KUPS.M
  • %System%\MSIMM.dll - also detected as BKDR_KUPS.M

(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 backdoor connects to the following URL(s) to check for an Internet connection:

  • download.windowsupdate.com

It does the following:

  • Injects the codes of the .DLL component MSIMM.DLL to the legitimate application svchost.exe that loads the .DLL component fixmapi.DLL into memory to perform its backdoor routines
  • Connects to the address {BLOCKED}.25.159 using port 80, if a connection is present.
  • Gathers the host name, IP address, and the Process ID of the running malware and use it to send the following requests to the said web site and waits for a reply:
    • POST http://0:/index.html?SearchXS={hostname}*{IP address}*{Process ID}
    However the said server does not currently reply to the requests of this malware.
  • Downloads or uploads file
  • Performs a directory search
  • Sends information such as Computer name, IP address and OS version
  • Lists down the contents of the affected machine
  • Modifies and searches the registry entries
  • Performs a shell command download

  SOLUTION

Minimum Scan Engine: 8.900
FIRST VSAPI PATTERN FILE: 7.720.07
FIRST VSAPI PATTERN DATE: 23 Dec 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 BKDR_KUPS.M

     TROJ_TARODROP.M

Step 3

Restart in Safe Mode

[ Learn More ]

Step 4

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\policies\Explorer\Run
    • WudfSvc = %System%\WudfSvc.exe

Step 5

Scan your computer with your Trend Micro product to delete files detected as BKDR_KUPS.M. 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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