ALIASES:

Trojan:Win32/Sirefef.P (Microsoft); W32/Sirefef.f (McAfee); Trojan.Zeroaccess (Symantec); Trojan.Win32.Sirefef.cr (v) (Sunbelt); Trojan.Generic.6793824 (FSecure)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted:

  • 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.

  TECHNICAL DETAILS

File Size: 45,968 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 29 Dec 2011

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.

Autostart Technique

This backdoor registers as a system service to ensure its automatic execution at every system startup by adding the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
services\.i8042prt

Other System Modifications

This backdoor adds the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\.i8042prt
Type = "1"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\.i8042prt
Start = "3"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\.i8042prt
ImagePath = "\*"

Dropping Routine

This backdoor drops the following files:

  • U
  • L
  • ACPI#PNP0303#2&da1a3ff&0\L\enixkeeo
  • ACPI#PNP0303#2&da1a3ff&0\@

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine: 9.200
FIRST VSAPI PATTERN FILE: 8.674.02
FIRST VSAPI PATTERN DATE: 29 Dec 2011
VSAPI OPR PATTERN File: 8.675.00
VSAPI OPR PATTERN Date: 30 Dec 2011

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

Restart in Safe Mode

[ Learn More ]

Step 3

Delete this registry key

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services
    • .i8042prt

Step 4

Delete this registry value

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\.i8042prt
    • Type = "1"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\.i8042prt
    • Start = "3"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\.i8042prt
    • ImagePath = "\*"

Step 5

Search and delete these files

[ 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.
  • U
  • L
  • ACPI#PNP0303#2&da1a3ff&0\L\enixkeeo
  • ACPI#PNP0303#2&da1a3ff&0\@

Step 6

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