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BKDR_ZACCESS.NTW
Malware type: Backdoor
Destructive: No
Platform: Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)
Encrypted: Yes
In the wild: Yes

Overview


Infection Channel: Downloaded from the Internet

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

It executes commands from a remote malicious user, effectively compromising the affected system. It connects to a website to send and receive information.

Technical Details


File size: Varies
File type: EXE
Memory resident: Yes
Initial samples received date: 05 Feb 2013
Payload: Terminates processes, Compromises system security

Arrival Details

This backdoor may be downloaded by the following malware/grayware from remote sites:

  • JAVA_EXPLOYT.NTW

Installation

This backdoor drops the following component file(s):

  • %User Temp%\msimg32.dll - detected as BKDR_ZACESS.SMQQ

(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, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.)

It drops the following non-malicious file:

  • %User Temp%\InstallFlashPlayer.exe

(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, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.)

Its DLL component is injected to the following process(es):

  • explorer.exe
  • svchost.exe

It creates the following folders:

  • %Application Data%\{GUID}\L
  • %Application Data%\{GUID}\U
  • %Windows%\Installer\{GUID}\L
  • %Windows%\Installer\{GUID}\U

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming on Windows Vista and 7.. %Windows% is the Windows folder, which is usually C:\Windows.)

Other System Modifications

This backdoor deletes the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
services\BITS

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
services\iphlpsvc

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
services\MpsSvc

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
services\SharedAccess

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
services\WinDefend

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
services\wscsvc

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
services\wuauserv

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\Run\
Windows Defender

Backdoor Routine

This backdoor executes the following commands from a remote malicious user:

  • Download and execute arbitrary files
  • Get drive information

It connects to the following websites to send and receive information:

  • http://j.{BLOCKED}d.com/app/geoip.js

Process Termination

This backdoor terminates processes or services that contain any of the following strings if found running in the affected system's memory:

  • wscntfy.exe
  • MSASCui.exe
  • MpCmdRun.exe
  • NisSrv.exe
  • msseces.exe
  • SharedAccess
  • windefend
  • MsMpSvc
  • iphlpsvc
  • wscsvc
  • mpssvc

NOTES:

It patches %System%\services.exe and saves the original copy in %System%\Winsxs\Backup\services.exe.

  • Patched 64-bit %System%\services.exe - detected as PTCH64_ZACCESS.A
  • Patched Win7 32-bit %System%\services.exe - detected as PTCH_ZACCESS.A

It connects to the following website to simulate clicking on pay-per-install links:

  • www.{BLOCKED}reecounters.com/5699002-2F6F334BF9ACF1B2401D3874A5B0C048/counter.img?theme={Random Value}&digits=10&siteId={Site ID}

Solution


Minimum scan engine: 9.300
First VSAPI Pattern File: 9.708.03
First VSAPI Pattern Release Date: 05 Feb 2013
VSAPI OPR Pattern Version: 9.709.00
VSAPI OPR Pattern Release Date: 06 Feb 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

Remove the malware/grayware file dropped/downloaded by BKDR_ZACCESS.NTW

Step 3

Remove the malware/grayware file that dropped/downloaded BKDR_ZACCESS.NTW

Step 4

Restart in Safe Mode

[ Learn more ]

Step 5

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.
  • %Application Data%\{GUID}\L
  • %Application Data%\{GUID}\U
  • %Windows%\Installer\{GUID}\L
  • %Windows%\Installer\{GUID}\U

Step 6

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

Step 7

Restore these deleted registry keys/values from backup

*Note: Only Microsoft-related keys/values will be restored. If the malware/grayware also deleted registry keys/values related to programs that are not from Microsoft, please reinstall those programs on your computer.


  • HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\BITS
  • HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\iphlpsvc
  • HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\MpsSvc
  • HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\SharedAccess
  • HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\WinDefend
  • HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\wscsvc
  • HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\wuauserv
  • HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run\Windows Defender

Step 8

Restore these deleted files from backup

*Note: Only Microsoft-related keys/values will be restored. If this malware/grayware also deleted registry keys/values related to programs that are not from Microsoft, please reinstall those programs on your computer.


NOTES:

Please perform this step before proceeding to Step 8:

Move services.exe from %System%\Winsxs\Backup to %System%.


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Analysis By: Michael Cabel

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