Analysis by: Nikko Tamana
ALIASES:

W32/ZAccess.BMLR!tr.bdr (Fortinet), Trojan.Win32.Sirefef (Ikarus), Backdoor.Win32.ZAccess.bmlr (Kaspersky), Trojan:Win32/Sirefef.gen!E (Microsoft), Win32/Sirefef.EV trojan (NOD32)

 PLATFORM:

Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

This Trojan may be dropped by other malware.

It requires its main component to successfully perform its intended routine. It is used to load and execute a file.

  TECHNICAL DETAILS

File Size: 65,536 bytes
File Type: DLL
Initial Samples Received Date: 07 Mar 2013

Arrival Details

This Trojan may be dropped by other malware.

Installation

This Trojan drops the following copies of itself into the affected system:

  • %System Root%\RECYCLER\S-1-5-18\{random}\n
  • %System Root%\$Recycle.Bin\S-1-5-18\{random}\n

(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)

Other Details

This Trojan requires its main component to successfully perform its intended routine.

It is used to load and execute the following file:

  • %System Root%\RECYCLER\S-1-5-18\${GUID}\U\80000032.@
  • %System Root%\$Recycle.Bin\S-1-5-18\${GUID}\U\80000032.@

(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)

  SOLUTION

Minimum Scan Engine: 9.300
FIRST VSAPI PATTERN FILE: 9.774.07
FIRST VSAPI PATTERN DATE: 07 Mar 2013
VSAPI OPR PATTERN File: 9.775.00
VSAPI OPR PATTERN Date: 08 Mar 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

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.
  • %System Root%\RECYCLER\S-1-5-18\${GUID}\U\80000032.@
  • %System Root%\$Recycle.Bin\S-1-5-18\${GUID}\U\80000032.@

Step 3

Scan your computer with your Trend Micro product to delete files detected as TROJ_SIREFEF.AQI. 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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