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BKDR_ZACCESS.YA

June 18, 2013
 ALIASES:

TrojanDropper:Win32/Sirefef (Microsoft); RDN/Generic BackDoor!mv (McAfee); Trojan.Zbot (Symantec); Backdoor.Win32.ZAccess.cdnt (Kaspersky); Trojan.Win32.Generic!BT (Sunbelt); Trojan horse BackDoor.Generic17.DXK (AVG)

 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:

141,824 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

15 Jun 2013

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.

Other System Modifications

This backdoor adds the following registry keys:

HKEY_CURRENT_USER\Software\Classes\
clsid

HKEY_CURRENT_USER\clsid\{fbeb8a05-beee-4442-804e-409d6c4515e9}

HKEY_CURRENT_USER\clsid\{fbeb8a05-beee-4442-804e-409d6c4515e9}\
InprocServer32

It adds the following registry entries:

HKEY_CURRENT_USER\clsid\{fbeb8a05-beee-4442-804e-409d6c4515e9}\
InprocServer32
ThreadingModel = "Both"

Dropping Routine

This backdoor drops the following files:

  • %System Root%\RECYCLER
  • %System Root%\RECYCLER\S-1-5-21-1645522239-1292428093-682003330-1003
  • @
  • n
  • %System Root%\RECYCLER\S-1-5-18

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

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine:

9.300

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

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_CURRENT_USER\Software\Classes
    • clsid
  • In HKEY_CURRENT_USER\clsid
    • {fbeb8a05-beee-4442-804e-409d6c4515e9}
  • In HKEY_CURRENT_USER\clsid\{fbeb8a05-beee-4442-804e-409d6c4515e9}
    • InprocServer32

Step 3

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_CURRENT_USER\clsid\{fbeb8a05-beee-4442-804e-409d6c4515e9}\InprocServer32
    • ThreadingModel = "Both"

Step 4

Search and delete these components

[ Learn More ]
There may be some components 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
  • %System Root%\RECYCLER\S-1-5-21-1645522239-1292428093-682003330-1003
  • @
  • n
  • %System Root%\RECYCLER\S-1-5-18

Step 5

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