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TROJ_ZEGOST.ECB

February 19, 2013
 Analysis by: Jaime Benigno Reyes
 ALIASES:

Trojan.Win32.Jorik.Zegost.pno (Kaspersky), Trojan-Dropper.Win32.Jazuz (Ikarus), Gen:Trojan.Heur.iyW@!3mqccjb (BitDefender), Dropper.Rozena (AVG)

 PLATFORM:

Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Spammed via email


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

It executes then deletes itself afterward.

  TECHNICAL DETAILS

File Size:

134,656 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

14 Feb 2013

Payload:

Drops files, Executes files

Arrival Details

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

Installation

This Trojan then creates the following non-malicious file(s):

  • %User Temp%\{malware file name}.hwp
  • %User Temp%\ope{random}.tmp.bat - deleted afterwards

(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, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.)

It drops and executes the following files:

  • %User Temp%\mew11.exe - detected as TROJ_DROPPER.ECB

(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, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.)

It executes then deletes itself afterward.

NOTES:

This Trojan arrives as an attachment using the file name {malware file name}.hwp {plus trailing spaces}.exe.

  SOLUTION

Minimum Scan Engine:

9.300

FIRST VSAPI PATTERN FILE:

9.726.03

FIRST VSAPI PATTERN DATE:

14 Feb 2013

VSAPI OPR PATTERN File:

9.727.00

VSAPI OPR PATTERN Date:

15 Feb 2013

Step 1

Before doing any scans, Windows XP, Windows Vista, and Windows 7 users must disable System Restore to allow full scanning of their computers.

Step 2

Remove malware/grayware files dropped/downloaded by TROJ_ZEGOST.ECB

Step 3

Identify and terminate files detected as TROJ_ZEGOST.ECB

[ Learn More ]
  1. Windows Task Manager may not display all running processes. In this case, please use a third-party process viewer, preferably Process Explorer, to terminate the malware/grayware/spyware file. You may download the said tool here.
  2. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  3. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

Step 4

Search and delete this file

[ Learn More ]
There may be some 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}.hwp

Step 5

Scan your computer with your Trend Micro product to delete files detected as TROJ_ZEGOST.ECB. 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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