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BKDR_CAPHAW.BN

March 24, 2014
 Analysis by: Mark Joseph Manahan
 ALIASES:

Mal/EncPk-AER (Sophos) ,Trojan horse ScreenLocker.AK (AVG) ,Backdoor.Win32.Caphaw (Ikarus) ,HEUR:Trojan.Win32.Generic (Kaspersky) ,Backdoor:Win32/Caphaw.D (Microsoft) ,BackDoor-FHI (McAfee) ,a variant of Win32/Kryptik.AOVX trojan (Eset) ,Trojan.Shylock (Symantec) ,Trj/Caphaw.gen (Panda) ,Trojan.Win32.Caphaw.ga (v) (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.

It executes then deletes itself afterward.

  TECHNICAL DETAILS

File Size:

294,912 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

13 Mar 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 the following copies of itself into the affected system:

  • %Application Data%\{random folder found}\{filename found in %System%}

(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.)

It executes then deletes itself afterward.

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 {random CLSID} = "%Application Data%\
{random folder found}\{filename found in %System%}
{random CLSID} = "%Application Data%\{random folder found}\{filename found in %System%}"

Other Details

This backdoor connects to the following possibly malicious URL:

  • {BLOCKED}ctions.su
  • {BLOCKED}ctions.cc
  • {BLOCKED}s.cc

NOTES:

This malware contains anti-emulation technique thus will not execute in Virtual Environments.

  SOLUTION

Minimum Scan Engine:

9.700

FIRST VSAPI PATTERN FILE:

10.662.05

FIRST VSAPI PATTERN DATE:

13 Mar 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

Scan your computer with your Trend Micro product and note files detected as BKDR_CAPHAW.BN

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
    • {random CLSID} = "%Application Data%\{random folder found}\{filename found in %System%}"

Step 5

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