Analysis by: Christopher Daniel So
ALIASES:

TrojanDownloader:Win32/Waledac.c (Microsoft), Trojan.Win32.Pakes.owa (Kaspersky), W32/SLM9X.A@mm (Fortinet)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

This Trojan may be dropped by other malware. It may be unknowingly downloaded by a user while visiting malicious websites.

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

  TECHNICAL DETAILS

File Size: 18,944 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 31 Mar 2011
Payload: Downloads files

Arrival Details

This Trojan may be dropped by other malware.

It may be unknowingly downloaded by a user while visiting malicious websites.

Download Routine

This Trojan accesses the following websites to download files:

  • http://{BLOCKED}r.com/client1.exe

It saves the files it downloads using the following names:

  • %Temp%\_ex-68.exe

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

Trend Micro detects the dowloaded file as:

  • WORM_KELIHOS.CDS

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

NOTES:
This malware may be downloaded from links in email messages sent out by WORM_KELIHOS.CDS.

  SOLUTION

Minimum Scan Engine: 8.900
FIRST VSAPI PATTERN FILE: 7.942.05
FIRST VSAPI PATTERN DATE: 31 Mar 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

Remove malware files dropped/downloaded by TROJ_KELIHOS.SMA

Step 3

Scan your computer with your Trend Micro product to delete files detected as TROJ_KELIHOS.SMA. 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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