TROJ_XDROP.XLS

May 21, 2011
 Analysis by: Karl Dominguez
 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Propagates via software vulnerabilities, Spammed via email

This malware has received attention from independent media sources and/or other security firms. It exploits CVE-2009-3129 to drop another malware that then drops a backdoor application. The backdoor then connects to a deceiving URL purportedly related to Trend Micro and Skype.

To get a one-glance comprehensive view of the behavior of this Trojan, refer to the Threat Diagram shown below.

This malware takes advantage of certain vulnerabilities in order to drop malware onto affected systems.

This Trojan arrives as an attachment to email messages spammed by other malware/grayware or malicious users.

It executes the dropped file(s). As a result, malicious routines of the dropped files are exhibited on the affected system.

  TECHNICAL DETAILS

File Size:

135,191 bytes

File Type:

XLS

Memory Resident:

No

Initial Samples Received Date:

21 May 2011

Payload:

Drops files

Arrival Details

This Trojan arrives as an attachment to email messages spammed by other malware/grayware or malicious users.

Installation

This Trojan drops the following files:

  • %User Temp%\ccccc.exe - detected as TROJ_FARFLI.XLS

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003.)

Dropping Routine

This Trojan takes advantage of the following software vulnerabilities to drop malicious files:

It executes the dropped file(s). As a result, malicious routines of the dropped files are exhibited on the affected system.

NOTES:

Other Details

More information on this vulnerability can be found below:

To avoid suspicion, it drops and opens the following non-malicious .XLS file:

  • %User Temp%\{malware file name}.xls

  SOLUTION

Minimum Scan Engine:

8.900

FIRST VSAPI PATTERN FILE:

8.170.04

FIRST VSAPI PATTERN DATE:

21 May 2011

VSAPI OPR PATTERN File:

8.171.00

VSAPI OPR PATTERN Date:

21 May 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_XDROP.XLS

    TROJ_FARFLI.XLS

Step 3

Search and delete this file

[ 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.
  • %User Temp%\{malware file name}.xls

Step 4

Scan your computer with your Trend Micro product to delete files detected as TROJ_XDROP.XLS. 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 5

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.

NOTES:


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