Analysis by: Adrian Cofreros
 PLATFORM:

Windows XP (64-bit), Windows Vista (64-bit), Windows 7 (64-bit)

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

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

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: 184,306 bytes
File Type: DLL
Memory Resident: Yes
Initial Samples Received Date: 05 Aug 2014
Payload: Downloads files, Compromises system security

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 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\RunOnce
CryptoUpdate = "%System%\regsvr32.exe /s "{malware path}\{malware filename and extension}""

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
CryptoUpdate = "%System%\regsvr32.exe /s "{malware path}\{malware filename and extension}""

Other System Modifications

This backdoor adds the following registry keys:

HKEY_CURRENT_USER\Software\Microsoft\
SystemCertificates\CA\Certificates\
5A82739996ED9EBA18F1BBCDCCA62D2C1D670C

It adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
SystemCertificates\CA\Certificates\
5A82739996ED9EBA18F1BBCDCCA62D2C1D670C
Blob{value} = "{hex values}"

Backdoor Routine

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

  • Updates the dll binary file
  • Receives and executes arbitrary code
  • Updates C&C configuration the following registry key:
    HKEY_CURRENT_USER\Software\Microsoft\SystemCertificates\CA\Certificates\5A82739996ED9EBA18F1BBCDCCA62D2C1D670C

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

  • {BLOCKED}.{BLOCKED}.186.40:777
  • {BLOCKED}.{BLOCKED}.186.29:777
  • {BLOCKED}.{BLOCKED}.186.55:777
  • {BLOCKED}.{BLOCKED}.127.3:777
  • {BLOCKED}.{BLOCKED}.236.225:80/about/sites

Download Routine

This backdoor saves the files it downloads using the following names:

  • %Application Data%\Microsoft\Crypto\RSA\cert_v{value1}_{value2}.tpl

(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.)

  SOLUTION

Minimum Scan Engine: 9.700

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

Note that not all files, folders, and registry keys and entries are installed on your computer during this malware's/spyware's/grayware's execution. This may be due to incomplete installation or other operating system conditions. If you do not find the same files/folders/registry information, please proceed to the next step.

Step 3

Scan your computer with your Trend Micro product and note files detected as BKDR64_BLYPT.E

Step 4

Restart in Safe Mode

[ Learn More ]

Step 5

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\RunOnce
    • CryptoUpdate = "%System%\regsvr32.exe /s "{malware path}\{malware filename and extension}""
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • CryptoUpdate = "%System%\regsvr32.exe /s "{malware path}\{malware filename and extension}""

Step 6

Delete this registry key

[ 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\SystemCertificates\CA\Certificates
    • 5A82739996ED9EBA18F1BBCDCCA62D2C1D670C

Step 7

Search and delete these files

[ Learn More ]
There may be some files that are hidden. Please make sure you check the Search Hidden Files and Folders checkbox in the "More advanced options" option to include all hidden files and folders in the search result.

Step 8

Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR64_BLYPT.E. 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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