Analysis by: Sabrina Lei Sioting
 Modified by: Michael Cabel
 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

It drops and opens a non-malicious .PDF file to trick the user that the file is non- malicious.

Upon execution, it checks the version of the Adobe Acrobat on the system. If the version is 9.4 or below, it attempts to exploit specific vulnerabilities to drop and execute files.

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

  TECHNICAL DETAILS

File Size: 773,222 bytes
Initial Samples Received Date: 20 Dec 2011
Payload: Drops files

Installation

This Trojan drops the following component file(s):

  • %User Profile%\Local Settings\fabc.scr
  • %User Profile%\Local Settings\log1.txt
  • %User Profile%\Local Settings\abc.scr - BKDR_FYNLOS.A

(Note: %User Profile% is the current user's profile folder, which is usually C:\Windows\Profiles\{user name} on Windows 98 and ME, C:\WINNT\Profiles\{user name} on Windows NT, and C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003.)

It drops the following non-malicious file:

  • %User Profile%\Local Settings\MERRY_CHRISTMAS.pdf

(Note: %User Profile% is the current user's profile folder, which is usually C:\Windows\Profiles\{user name} on Windows 98 and ME, C:\WINNT\Profiles\{user name} on Windows NT, and C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003.)

Dropping Routine

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

NOTES:
It drops and opens a non-malicious .PDF file to trick the user that the file is non-malicious:

Upon execution, it checks the version of the Adobe Acrobat on the system. If the version is 9.4 or below, it attempts to exploit the following vulnerabilities to drop and execute files:

It joins the files LOG1.TXT and FABC.SCR to form the file ABC.SCR, which it executes afterwards.

  SOLUTION

Minimum Scan Engine: 9.200
FIRST VSAPI PATTERN FILE: 8.656.04
FIRST VSAPI PATTERN DATE: 20 Dec 2011
VSAPI OPR PATTERN File: 8.657.00
VSAPI OPR PATTERN Date: 21 Dec 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_PIDIEF.EGR

Step 3

Search and delete these files

[ 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 Profile%\Local Settings\fabc.scr
%User Profile%\Local Settings\log1.txt
%User Profile%\Local Settings\MERRY_CHRISTMAS.pdf

Step 4

Scan your computer with your Trend Micro product to delete files detected as TROJ_PIDIEF.EGR. 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.


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