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BKDR_ZEGOST.KX

July 15, 2013
 Analysis by: Jaime Benigno Reyes
 ALIASES:

Trojan:Win32/Redosdru.L (Microsoft), Backdoor.Win32.Zegost (Ikarus)

 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: Backdoor

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW


This backdoor arrives as a component bundled with malware/grayware packages.

It executes commands from a remote malicious user, effectively compromising the affected system.

It requires its main component to successfully perform its intended routine.

  TECHNICAL DETAILS

File Size:

94,759 bytes

File Type:

DLL

Memory Resident:

Yes

Initial Samples Received Date:

11 Jul 2013

Payload:

Connects to URLs/IPs, Collects system information, Downloads files, Terminates processes

Arrival Details

This backdoor arrives as a component bundled with malware/grayware packages.

Installation

This backdoor drops the following files:

  • %System%\pitemp.dat

(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.)

Backdoor Routine

This backdoor executes the following commands from a remote malicious user:

  • Browse files
  • Download and execute arbitrary files
  • Execute shell commands
  • Enumerate running processes
  • Terminate processes
  • Get drive information

It connects to the following URL(s) to send and receive commands from a remote malicious user:

  • http://www.{BLOCKED}ons.net:443

Other Details

This backdoor requires its main component to successfully perform its intended routine.

  SOLUTION

Minimum Scan Engine:

9.300

FIRST VSAPI PATTERN FILE:

10.148.01

FIRST VSAPI PATTERN DATE:

11 Jul 2013

VSAPI OPR PATTERN File:

10.149.00

VSAPI OPR PATTERN Date:

11 Jul 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

Scan your computer with your Trend Micro product and note files detected as BKDR_ZEGOST.KX

Step 3

Restart in Safe Mode

[ Learn More ]

Step 4

Search and delete the files detected as BKDR_ZEGOST.KX

*Note: Some component files may be 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.

To stop the malware/grayware from running when certain files are opened:

For Windows 2000, Windows XP, and Windows Server 2003:

  1. Right-click Start then click Search....
  2. In the Named input box, type the name of the file that was detected earlier.
  3. In the Look In drop-down list, select My Computer then press Enter.
  4. Once located, select the file then press SHIFT+DELETE to delete it.

For Windows Vista and Windows 7:

  1. Click Start>Computer.
  2. In the Search Computer input box, type the name of the file detected earlier, and press Enter.
  3. Once located, select the file then press SHIFT+DELETE to delete it.
    *Note: Read the following Microsoft page if these steps do not work on Windows 7.

Step 5

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.  
  • %System%\pitemp.dat

Step 6

Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_ZEGOST.KX. 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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