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BKDR_THOPER.BN

October 09, 2012
 Analysis by: Rhena Inocencio
 ALIASES:

Backdoor:Win32/Thoper.E (Microsoft), Downloader-CRE (McAfee), W32/Agent2.EPHI!tr (Fortinet)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: Yes

  • 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 does not have any propagation routine.

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

It does not have any downloading capability.

It does not have any information-stealing capability.

  TECHNICAL DETAILS

File Size:

225,280 bytes

File Type:

DLL

Memory Resident:

Yes

Initial Samples Received Date:

29 Aug 2012

Payload:

Compromises system security

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.

Propagation

This backdoor does not have any propagation routine.

Backdoor Routine

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

  • Enumerate TCP connections
  • Enumerate network shared folders and devices
  • Edit registry keys
  • Enumerate values in a registry key
  • Start a process
  • Start a remote CMD
  • Start a service
  • Modify the configuration of a service
  • Send control code to a service
  • Delete a service
  • Get service info
  • Start a remote desktop
  • Open a file
  • Perform a file operation
  • Start a hidden process
  • Create a directory/folder
  • List the contents of a folder
  • Read an entire file
  • Drop a file from C&C
  • Get information of all drives
  • Lock Windows
  • Logoff
  • Reboot
  • Shutdown
  • Connect to a database server and execute a SQL statement (server name is a parameter of this command)
  • Display a message box (The message to be displayed is a parameter of this command)

Download Routine

This backdoor does not have any downloading capability.

Information Theft

This backdoor does not have any information-stealing capability.

NOTES:

This backdoor opens a random port to wait for a connection. Once a successful connection is established, the remote user executes commands on the affected system.

It does not have rootkit capabilities.

It does not exploit any vulnerability.

  SOLUTION

Minimum Scan Engine:

9.200

FIRST VSAPI PATTERN FILE:

9.358.02

FIRST VSAPI PATTERN DATE:

29 Aug 2012

VSAPI OPR PATTERN File:

9.359.00

VSAPI OPR PATTERN Date:

30 Aug 2012

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

Scan your computer with your Trend Micro product and note files detected as BKDR_THOPER.BN

Step 3

Restart in Safe Mode

[ Learn More ]

Step 4

Search and delete the file detected as BKDR_THOPER.BN

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden files in the search result.

Step 5

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