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BKDR_ZAPCHAST.SG

October 09, 2012
 ALIASES:

Backdoor:Win32/Fynloski.A (Microsoft); Backdoor.Breut (Symantec)

 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

Infection Channel:

Downloaded from the Internet

This backdoor gathers certain information on the affected system.

It logs active windows and user key strokes.

It is capable of executing several commands on the affected system.

This backdoor may be downloaded by other malware/grayware/spyware from remote sites.

It connects to a website to send and receive information.

  TECHNICAL DETAILS

File Size:

459,948 bytes

File Type:

Other

Memory Resident:

Yes

Initial Samples Received Date:

13 Feb 2012

Payload:

Compromises system security, Connects to URLs/IPs, Steals information

Arrival Details

This backdoor may be downloaded by other malware/grayware/spyware from remote sites.

Installation

This backdoor drops the following files:

  • %User Temp%\GoogleUp-date.exe - also detected as BKDR_ZAPCHAST.SG
  • %User Temp%\_$temp - encrypted component
  • %User Startup%\(Empty).lnk - autostart component

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003.. %User Startup% is the current user's Startup folder, which is usually C:\Windows\Profiles\{user name}\Start Menu\Programs\Startup on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Start Menu\Programs\Startup on Windows NT, and C:\Documents and Settings\{User name}\Start Menu\Programs\Startup.)

It creates the following folders:

  • %User Temp%\dclogs

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003.)

It adds the following mutexes to ensure that only one of its copies runs at any one time:

  • DC_MUTEX-BU4N34A

Other System Modifications

This backdoor adds the following registry keys:

HKEY_CURRENT_USER\Software\DC3_FEXEC

Backdoor Routine

This backdoor connects to the following websites to send and receive information:

  • {BLOCKED}.{BLOCKED}.0.28

Stolen Information

This backdoor saves the stolen information in the following file:

  • %User Temp%\dclogs\{current date}-{number}.dc

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003.)

NOTES:

It gathers the following information on the affected system:

  • Admin rights
  • Computer/User name
  • HWID
  • Language/Country
  • Operating System information
  • RAM used
  • Web Cam information

It logs active windows and user key strokes.

It is capable of executing the following commands:

  • Disable notifications of antivirus software
  • Display a message box
  • Download an updated copy of itself
  • Download and execute files
  • List active windows
  • Manipulate files
  • Manipulate processes
  • Manipulate registries
  • Modify priveleges
  • Modify the hosts file
  • Modify user groups
  • Monitor webcam activity
  • Open command prompt
  • Steal passwords
  • Uninstall applications
  • Uninstall itself

  SOLUTION

Minimum Scan Engine:

9.200

FIRST VSAPI PATTERN FILE:

8.776.04

FIRST VSAPI PATTERN DATE:

13 Feb 2012

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

Identify and terminate files detected as BKDR_ZAPCHAST.SG

[ Learn More ]
  1. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  2. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

Step 3

Search and delete these folders

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result. %User Temp%\dclogs

Step 4

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.  %User Temp%\_$temp
%User Startup%\(Empty).lnk

Step 5

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
    • DC3_FEXEC

Step 6

Scan your computer with your Trend Micro product to delete files detected as BKDR_ZAPCHAST.SG. 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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