BKDR_FUCOBHA.EH

 Analysis by: Nikko Tamana

 ALIASES:

TrojanSpy:Win32/Fucobha.A (Microsoft), Backdoor.Hormesu!gen2 (Norton), Trojan-Spy.Win32.Fucobha (Ikarus), a variant of Win32/Fucobha.A trojan (NOD32)

 PLATFORM:

Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)

 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:

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.

However, as of this writing, the said sites are inaccessible.

  TECHNICAL DETAILS

File Size:

126,976 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

19 Sep 2013

Payload:

Connects to URLs/IPs, Compromises system security, Downloads files, Collects system 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 drops the following component file(s):

  • %Windows%\wdmaud.drv - also detected as BKDR_FUCOBHA.EH

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

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

  • myhorse_macfee

Backdoor Routine

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

  • Download Files
  • Upload Files
  • Execute Files
  • Perform Remote Shell

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

  • http://{BLOCKED}n.net/jd/upload.aspx?filepath=info&filename={Host Name}_{Local IP Address}.jpg
  • http://{BLOCKED}n.net/jd/upload.aspx?filepath=ok&filename={Host Name}_{Local IP Address}.jpg

Download Routine

This backdoor accesses the following websites to download files:

  • http://{BLOCKED}n.net/jd/order/{Host Name}_{Local IP Address}.jpg

It saves the files it downloads using the following names:

  • %User Temp%\order.dat

(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.)

Information Theft

This backdoor gathers the following data:

  • Host Name
  • Local IP Address
  • Proxy Server (if any)
  • Currently logged on user name
  • System directory
  • OS and System Version
  • List of active processes in the machine

Stolen Information

This backdoor saves the stolen information in the following file:

  • %User Temp%\tmp.dat

(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 sends the gathered information via HTTP POST to the following URL:

  • http://{BLOCKED}n.net/jd/upload.aspx?filepath=info&filename={Host Name}_{Local IP Address}.jpg
  • http://{BLOCKED}n.net/jd/upload.aspx?filepath=ok&filename={Host Name}_{Local IP Address}.jpg

Other Details

However, as of this writing, the said sites are inaccessible.

NOTES:

It deletes %User Temp%\tmp.dat after the stolen information are sent.

It only executes properly on Windows Vista and later Windows OS versions.

  SOLUTION

Minimum Scan Engine:

9.300

FIRST VSAPI PATTERN FILE:

10.298.05

FIRST VSAPI PATTERN DATE:

24 Sep 2013

VSAPI OPR PATTERN File:

10.299.00

VSAPI OPR PATTERN Date:

25 Sep 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

Restart in Safe Mode

[ Learn More ]

Step 3

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.
  • %Windows%\wdmaud.drv
  • %User Temp%\order.dat
  • %User Temp%\tmp.dat

Step 4

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


Did this description help? Tell us how we did.