BKDR_KULUOZ.WT

February 21, 2014
 Analysis by: Mark Joseph Manahan
 ALIASES:

Troj/Delf-FSD (Sophos) ,Found Luhe.Fiha.A (AVG) ,W32/Androm.BLNE!tr.bdr (Fortinet) ,W32/Trojan3.HEW (exact) (Fprot) ,Virus.Win32.Injector.CI (Ikarus) ,Backdoor.Win32.Androm.blne (Kaspersky) ,VirTool:Win32/Injector.CI (Microsoft) ,RDN/Generic BackDoor!wp (McAfee) ,Win32/TrojanDownloader.Zortob.B trojan (Eset) ,Trojan.Fakeavlock (Symantec) ,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: 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:

183,808 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

21 Feb 2014

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 a copy of itself in the following folders using different file names:

  • %AppDataLocal%\{random filename}.exe

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

Autostart Technique

This backdoor creates the following registry entries to enable automatic execution of dropped component at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{Random Value} = "%AppDataLocal%\{Random Filename}.exe"

Other System Modifications

This backdoor adds the following registry keys:

HKEY_CURRENT_USER\Software\{Random Value}

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

HKEY_CURRENT_USER\Software\{Random Value}
{Random} = "{Value}"

Other Details

This backdoor connects to the following possibly malicious URL:

  • http://{BLOCKED}.{BLOCKED}.199.214:8080