Analysis by: Cris Nowell Pantanilla
ALIASES:

Backdoor.Win32.ZAccess.ob (Kaspersky) Trojan.Zeroaccess (Symantec)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

 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 is a component of other malware.

It does not have any propagation routine.

It does not have any backdoor routine.

It does not have any downloading capability.

It does not have any information-stealing capability.

  TECHNICAL DETAILS

File Size: 816 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 22 Sep 2011
Payload: Displays graphics/image

Arrival Details

This Trojan may be dropped by the following malware:

  • FAKEAV Family

Installation

This Trojan is a component of other malware.

Propagation

This Trojan does not have any propagation routine.

Backdoor Routine

This Trojan does not have any backdoor routine.

Download Routine

This Trojan does not have any downloading capability.

Information Theft

This Trojan does not have any information-stealing capability.

NOTES:

Rootkit Capabilities

This malware does not have rootkit capabilities.

Other Details

It prevents the system from executing EXE files by monitoring the ntdll.ZwCreateFile API. Once a file is executed, it blocks the file and display a message similar to the one below:

This prevents the user to run programs in the compromised system.

This malware does not exploit any vulnerability.

  SOLUTION

Minimum Scan Engine: 9.200
FIRST VSAPI PATTERN FILE: 8.472.04
FIRST VSAPI PATTERN DATE: 04 Oct 2011
VSAPI OPR PATTERN File: 8.473.00
VSAPI OPR PATTERN Date: 05 Oct 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

Scan your computer with your Trend Micro product to delete files detected as TROJ_FAKEAL.K. 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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