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BKDR_AGENT.APLL

October 09, 2012
 Analysis by: Sabrina Lei Sioting
 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

This backdoor arrives as a file that exports the functions of other malware/grayware. It arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites. It arrives as a component bundled with malware/grayware packages.

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

  TECHNICAL DETAILS

File Size:

107,520 bytes

File Type:

DLL

Initial Samples Received Date:

17 May 2012

Arrival Details

This backdoor arrives as a file that exports the functions of other malware/grayware.

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

It arrives as a component bundled with malware/grayware packages.

Installation

This backdoor drops the following files:

  • %System%\rundll32.exe.xxt

(Note: %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.)

Other Details

This backdoor connects to the following possibly malicious URL:

  • http://{BLOCKED}.55.56:443/{random}.asp?{random}
  • http://{BLOCKED}.55.59:443/{random}.asp?{random}
  • http://{BLOCKED}sz.tw:443/{random}.asp?{random}

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

  SOLUTION

Minimum Scan Engine:

9.200

FIRST VSAPI PATTERN FILE:

9.118.03

FIRST VSAPI PATTERN DATE:

17 May 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

Search and delete this file

[ Learn More ]
There may be some component 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%\rundll32.exe.xxt

Step 3

Scan your computer with your Trend Micro product to delete files detected as BKDR_AGENT.APLL. 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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