Analysis by: Mark Joseph Manahan
ALIASES:

Trojan horse Agent4.BFKQ (AVG) ,W32/Agent.ABMIH!tr (Fortinet) ,Trojan.Win32.Agent (Ikarus) ,Trojan.Win32.Agent.abmih (Kaspersky) ,Trojan:Win32/Gatak (Microsoft) ,BackDoor-FGT!A2A7B3AAD631 (McAfee) ,a variant of Win32/Kryptik.BLGE trojan (Eset) ,Trojan.Zbot (Symantec) ,Generic (Panda) ,Trojan.Win32.Generic!BT (Sunbelt)

 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:
 INFORMATION EXPOSURE:

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel: Downloaded from the Internet, Dropped by other malware

This malware was found in January 2014 to be distributed as a key generator. Instead of generating keys, it downloads malware onto the affected system. Affected users may find malicious routines being exhibited in their systems.

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

This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It connects to certain websites to send and receive information.

  TECHNICAL DETAILS

File Size: 1,314,816 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 10 Jan 2014
Payload: Connects to URLs/IPs, Downloads files

Arrival Details

This Trojan 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 Trojan drops the following files:

  • %Application Data%\Microsoft\{random folder name}\{random file name} - encrypted

(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%\Skype\Phone\Skype.exe - also detected as TROJ_GATAK.FCK
  • %Application Data%\Google Talk\googletalk.exe - also detected as TROJ_GATAK.FCK
  • %Application Data%\advantage\AdVantage.exe - also detected as TROJ_GATAK.FCK

(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 Trojan adds the following registry entries to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
Skype = ""%Application Data%\Skype\Phone\Skype.exe" /nosplash /minimized"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
googletalk = ""%Application Data%\Google Talk\googletalk.exe" /autostart"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
advantage = "%Application Data%\advantage\AdVantage.exe"

Other System Modifications

This Trojan adds the following registry keys:

HKEY_CURRENT_USER\Software\Microsoft\
{random}

Other Details

Based on analysis of the codes, it has the following capabilities:

  • Update Self
  • Download and execute arbitrary files

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

  • {BLOCKED}.{BLOCKED}.43.100:80/existe/fermeture?guides=mm807555
  • {BLOCKED}.{BLOCKED}.154.72:80/altasure/oprobus?domaine=9394076
  • {BLOCKED}s.{BLOCKED}a.co.uk:80/renouvelement?technique=au3330080
  • {BLOCKED}a.{BLOCKED}o.com:80/altasure/oprobus?domaine=9394076
  • {BLOCKED}s.{BLOCKED}emr.com:80/nmodifier/type?spf=61200091
  • {BLOCKED}c.{BLOCKED}-of-inferno.us:80/persistent/client?ref=77790278
  • {BLOCKED}hrouth.{BLOCKED}dmindpowerhouse.com:80/calm/stay?void=32847490

  SOLUTION

Minimum Scan Engine: 9.700
FIRST VSAPI PATTERN FILE: 10.532.01
FIRST VSAPI PATTERN DATE: 10 Jan 2014
VSAPI OPR PATTERN File: 10.533.00
VSAPI OPR PATTERN Date: 11 Jan 2014

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

Restart in Safe Mode

[ Learn More ]

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\Software\Microsoft\Windows\CurrentVersion\Run
    • Skype = ""%Application Data%\Skype\Phone\Skype.exe" /nosplash /minimized"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • googletalk = ""%Application Data%\Google Talk\googletalk.exe" /autostart"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • advantage = "%Application Data%\advantage\AdVantage.exe"

Step 4

Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_GATAK.FCK. 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 5

The following created registry key(s) cannot be identified by the user since there are no reference values in the created key. The only way it can be identified is by comparing the present keys with a backup of the system registry. Note that the said key(s) do not have to be deleted since it won't be harmful to the system:

 
  • In HKEY_CURRENT_USER\Software\Microsoft
    • {random}


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