Analysis by: Mark Joseph Manahan
ALIASES:

Trojan:Win32/Sirefef.BC (Microsoft), Backdoor.Win32.ZAccess (Ikarus)

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

It is used to load and execute a file.

  TECHNICAL DETAILS

File Size: 47,616 bytes
File Type: DLL
Initial Samples Received Date: 18 Oct 2012

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.

It may be dropped by other malware.

Other Details

This backdoor is used to load and execute the following file:

  • %System%\z

(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.)

NOTES:

This malware exports functions used by other malwares for their backdoor routines.

  SOLUTION

Minimum Scan Engine: 9.300

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%\z

Step 3

Scan your computer with your Trend Micro product to delete files detected as BKDR_ZACCESS.NJ. 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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