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Threat Encyclopedia

BKDR_GATAKA.A

ANALYSIS BY

Jed Valderama


ALIASES:

Trojan:Win32/Gataka.D (Microsoft); PWS-Zbot.gen.ahw( McAfee); Trojan-Spy.Win32.Zbot.eomj (Kaspersky)

PLATFORM:

Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)

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, Dropped by other malware


This malware has the capability of downloading and installing plugins from a remote server. This feature allows the malware to be more flexible in its attacks. Affected users may find their personal information stolen due to the security of their systems being compromised.

To get a one-glance comprehensive view of the behavior of this Backdoor, refer to the Threat Diagram shown below.

This backdoor collects system information and remotely execute arbitrary commands or other applications.

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.

It executes commands from a remote malicious user, effectively compromising the affected system. However, as of this writing, the said sites are inaccessible.

It opens a hidden Internet Explorer window. It deletes the initially executed copy of itself.

TECHNICAL DETAILS

File Size:

225,280 bytes

File Type:

EXE

File Compression:

Morphine

Memory Resident:

Yes

Initial Samples Received Date:

14 Aug 2012

Payload:

Connects to URLs/IPs, Steals information, Collects system information

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.

Installation

This backdoor drops the following copies of itself into the affected system:

  • %Application Data%\{folder name 1}\{CLSID 1}\{malware file name}.exe

(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.)

It drops the following component file(s):

  • %Application Data%\{folder name 2}\{CSLID 2}\{random hex}.dat - non-malicious file

(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.)

It creates the following folders:

  • %Application Data%\{folder name 1}\{CLSID 1}
  • %Application Data%\{folder name 2}\{CSLID 2}

(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.)

It injects codes into the following process(es):

  • explorer.exe

Autostart Technique

This backdoor adds the following registry entries to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{malware file name} = "%Application Data%\{folder name 1}\{CLSID 1}\{malware file name}.exe"

Other System Modifications

This backdoor adds the following registry entries as part of its installation routine:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
StartProcIrq = "dword:0000000c"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
StartPage
CustomBarMenu = "{encrypted location of {random hex}.dat}"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
StartCurrId = "dword:00000009"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
StartCurrMask = "dword:0000003e"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
StartMainId = "dword:0000000a"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
StartMainMask = "dword:0000007e"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
PersistFile = "dword:00000003"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
PersistFolder = "dword:00000002"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
StartMenuMask = "dword:00015be1"

Backdoor Routine

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

  • Collect System Information
  • Browse Files and Folders
  • Connect to Server
  • Get AutoRun FilePath
  • Get AutoRun ValueName
  • Get Bot Id
  • Download and Install plugins/modules
  • Open Browser
  • Perform remote shell
  • Download and execute arbitrary files
  • Set AutoRun Value
  • Start As Client
  • Start As Server
  • Stop Client
  • Stop Server
  • Terminate itself

It connects to the following URL(s) to send and receive commands from a remote malicious user:

  • {BLOCKED}-summer.hu/ip.php
  • {BLOCKED}ly.com/ip.php
  • dns.{BLOCKED}g.cc/mak/g.php
  • {BLOCKED}rve.name/mak/g.php

However, as of this writing, the said sites are inaccessible.

Information Theft

This backdoor injects itself into the following web browsers to monitor searches made by the user on the following search engines:

  • iexplore.exe
  • maxthon.exe
  • opera.exe
  • firefox.exe
  • sol.exe

Other Details

This backdoor opens a hidden Internet Explorer window.

It deletes the initially executed copy of itself

NOTES:

The {folder name} and {malware file name} can be any of the following:

  • Adobe
  • Apple
  • Dropbox
  • Google
  • Google Inc
  • Identities
  • LicenseValidator
  • Macromedia
  • Media Center Programs
  • Media Player Classic
  • Microsoft
  • Microsoft Corporation
  • Mozilla
  • NtCoreDefender
  • NtGarbageCollector
  • Opera
  • RdcRpcController
  • renovator
  • RpcLowAccessPipe
  • RpcLowReader
  • RpcNtComm
  • RpcScheduler
  • RpcSearchIndexer
  • RpcWin32Router
  • RpcWin32Service
  • SearchHelper
  • Skype
  • TeamViewer
  • Upgrade
  • UpgradeChecker
  • UpgradeHelper
  • Validator
  • Win16Communicator
  • Win32Defender
  • Win32GlobalFinder
  • Win32RpcAccessCtrl
  • Win32RpcDecrypt
  • Win32Scheduler
  • Win32UserFinder
  • Win64Expected
  • Win64GarbageCollector
  • Windows Desktop Search
  • Windows Search
  • WindowsRpcAccess
  • WinRAR

SOLUTION

Minimum Scan Engine:

9.200

FIRST VSAPI PATTERN FILE:

9.320.07

FIRST VSAPI PATTERN DATE:

14 Aug 2012

VSAPI OPR PATTERN File:

9.321.00

VSAPI OPR PATTERN Date:

15 Aug 2012

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

Scan your computer with your Trend Micro product and note files detected as BKDR_GATAKA.A

Step 3

Restart in Safe Mode

[ Learn More ]

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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • {malware file name} = "%Application Data%\{folder name 1}\{CLSID 1}\{malware file name}.exe"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
    • StartProcIrq = "dword:0000000c"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\StartPage
    • CustomBarMenu = "{encrypted location of {random hex}.dat}"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
    • StartCurrId = "dword:00000009"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
    • StartCurrMask = "dword:0000003e"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
    • StartMainId = "dword:0000000a"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
    • StartMainMask = "dword:0000007e"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
    • PersistFile = "dword:00000003"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
    • PersistFolder = "dword:00000002"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
    • StartMenuMask = "dword:00015be1"

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%\{folder name 1}\{CLSID 1}
  • %Application Data%\{folder name 2}\{CSLID 2}

Step 6

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