BKDR_ZEGOST.YNQF

March 13, 2015
 Analysis by: Miguel Carlo Ang
 ALIASES:

Backdoor:Win32/Zegost.BZ(Microsoft), a variant of Win32/Farfli.BKX trojan(Eset)

 PLATFORM:

Windows

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Downloaded from the Internet, Dropped by other malware

This backdoor arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

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

  TECHNICAL DETAILS

File Size:

194,580 bytes

File Type:

, EXE

Memory Resident:

Yes

Initial Samples Received Date:

09 Mar 2015

Payload:

Compromises system security, Steals information

Arrival Details

This backdoor arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

Installation

This backdoor adds the following mutexes to ensure that only one of its copies runs at any one time:

  • x331597514.xicp.net

Autostart Technique

This backdoor adds the following registry entries to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
admin = "{path of initial ran malware}\{intial malware name}.exe"

Backdoor Routine

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

  • Remote Desktop Connections
  • Steal system information (OS details and CPU Information)
  • Create a hidden administrative backdoor account
  • Keylogging capabilities
  • Synthesize mouse motion and button clicks

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

  • {BLOCKED}7514.{BLOCKED}p.net:1588

NOTES:

The malware has the capability to install itself as a service but does not proceed with that routine.

  SOLUTION

Minimum Scan Engine:

9.750

FIRST VSAPI PATTERN FILE:

11.534.04

FIRST VSAPI PATTERN DATE:

07 Mar 2015

VSAPI OPR PATTERN File:

11.535.00

VSAPI OPR PATTERN Date:

08 Mar 2015

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

Note that not all files, folders, and registry keys and entries are installed on your computer during this malware's/spyware's/grayware's execution. This may be due to incomplete installation or other operating system conditions. If you do not find the same files/folders/registry information, please proceed to the next step.

Step 3

Restart in Safe Mode

[ Learn More ]

Step 4

Delete this registry value

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

 
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • admin = "{path of initial runned malware}\{intial malware name}.exe"

Step 5

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