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WORM_MSIL.TK

October 09, 2012
 Analysis by: Cris Nowell Pantanilla
 Modified by: Michael Cabel
 ALIASES:

Backdoor:Win32/Hupigon.EX [Microsoft], Worm.MSIL.Agent.gj [Kaspersky]

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

This worm arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It exploits software vulnerabilities to propagate to other computers across a network.

It saves downloaded files into certain folders. It executes the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system. As of this writing, the said sites are inaccessible.

  TECHNICAL DETAILS

File Size:

84,992 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

20 Jul 2011

Arrival Details

This worm arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

Propagation

This worm exploits the following software vulnerabilities to propagate to other computers across a network:

  • Server Service

Download Routine

This worm connects to the following website(s) to download and execute a malicious file:

  • {BLOCKED}o.jajaca.com
  • {BLOCKED}t.jajaca.com

It saves downloaded files into certain folders.

It then executes the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system.

As of this writing, the said sites are inaccessible.

Other Details

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

  • www.google.com

More information on this vulnerability can be found below:

NOTES:

This worm propagates by taking advantage of a vulnerability discovered in certain Microsoft operating systems that could allow remote code execution if an affected system received a specially crafted RPC request, which also contains a shellcode. It attempts to connect to other target systems by opening TCP threads or connections which scan for IP addresses.

Once this specially crafted RPC request reaches its target vulnerable system, the shellcode then downloads a copy of the worm from the affected system.

During this exploit, a high traffic on TCP port 445 is seen since this is the port that this worm uses.

  SOLUTION

Minimum Scan Engine:

8.900

FIRST VSAPI PATTERN FILE:

8.300.05

FIRST VSAPI PATTERN DATE:

20 Jul 2011

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

Scan your computer with your Trend Micro product to delete files detected as WORM_MSIL.TK. 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 3

Download and apply these security patches Refrain from using these products until the appropriate patches have been installed. Trend Micro advises users to download critical patches upon release by vendors.

(MS08-067) Vulnerability in Server Service Could Allow Remote Code Execution (958644)


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