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BKDR_DESTOVER.C

December 27, 2014
 Analysis by: Anthony Joe Melgarejo
 ALIASES:

Backdoor.Destover (Symantec), Trojan:Win32/NukeSped.D!dha (Micosoft), Trojan.Win32.Destover.e (Kasprsky)

 PLATFORM:

Windows

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:
 INFORMATION EXPOSURE:

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Dropped by other malware


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.

  TECHNICAL DETAILS

File Size:

53,248 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

10 Dec 2014

Payload:

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 and executes them:

  • {root directory of initial folder}:\igfxconf.exe

Autostart Technique

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
CurrentVersion\Run
IgfxConf = ""{root directory of initial folder}:\igfxconf.exe" /s"

HKEY_CURRENT_USER\Software\Microsoft\
CurrentVersion\Run
IgfxConf = ""{root directory of initial folder}:\igfxconf.exe" /s"

Backdoor Routine

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

  • Rename specified file or move to another directory
  • Send the type of each logical drive in the affected system
  • Download arbitrary files
  • Upload arbitrary files
  • Execute arbitrary files
  • Check for a specified file's existence
  • Terminate specified process
  • Send computer name and operating system version
  • Uninstall itself (including registry)
  • Steal archive files with certain extensions (.Z, .zip, .zoo, .arc, .lzh, .arj, .gz, .tgz)

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

  • {BLOCKED}.{BLOCKED}.81.73:444
  • {BLOCKED}.{BLOCKED}.71.18:444
  • {BLOCKED}.{BLOCKED}.112.69:443
  • {BLOCKED}.{BLOCKED}.20.68:443

NOTES:

The initial folder is the malware's location when it arrives in the affected system.

It checks for the existence of the following files:

  • c_1226705.nls

It first adds its Autostart registry to HKEY_LOCAL_MACHINE. If it fails, it will add it to HKEY_CURRENT_USER instead.

  SOLUTION

Minimum Scan Engine:

9.700

FIRST VSAPI PATTERN FILE:

11.338.05

FIRST VSAPI PATTERN DATE:

11 Dec 2014

VSAPI OPR PATTERN File:

11.339.00

VSAPI OPR PATTERN Date:

11 Dec 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_LOCAL_MACHINE\SOFTWARE\Microsoft\CurrentVersion\Run
    • IgfxConf = ""{root directory of initial folder}:\igfxconf.exe" /s"
  • In HKEY_CURRENT_USER\Software\Microsoft\CurrentVersion\Run
    • IgfxConf = ""{root directory of initial folder}:\igfxconf.exe" /s"

Step 4

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