Analysis by: Alvin Bacani
ALIASES:

Trojan.Fakeavlock (Symantec); Trojan-Dropper.Win32.Injector.icfe (Kaspersky)

 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: No

  • In the wild: Yes

  OVERVIEW

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

This backdoor is a variant of the malware family BLYPT. It uses binary large objects (BLOB) to store information in the affected system's registry. It also utilizes encryption. Users affected by this malware may find the security of their systems compromised.

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

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: 39,936 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 21 Sep 2013
Payload: 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.

Other System Modifications

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

HKEY_CURRENT_USER\Software\Microsoft\
SystemCertificates\CA\Certificates\
5A82739996ED9EBA18F1BBCDCCA62D2C1D670C
Blob = "{Encrypted configuration data}"

Backdoor Routine

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

  • Download and execute the main backdoor component

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

  • {BLOCKED}lution134.org:80
  • {BLOCKED}.{BLOCKED}.162.47:81
  • {BLOCKED}.{BLOCKED}.162.45:81
  • {BLOCKED}.{BLOCKED}.181.50:81
  • {BLOCKED}.{BLOCKED}.186.14:778
  • {BLOCKED}.{BLOCKED}.186.9:777
  • {BLOCKED}.{BLOCKED}.186.27:777
  • {BLOCKED}.{BLOCKED}.121.141:777
  • {BLOCKED}.{BLOCKED}.97.02:777
  • {BLOCKED}.{BLOCKED}.186.47:81
  • {BLOCKED}.{BLOCKED}.186.45:81

Download Routine

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

  • %Application Data%\Microsoft\Crypto\NTCRYPT{variable}.TPL
  • %Application Data%\Microsoft\Crypto\CERTV{variable}.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.)

Trend Micro detects the dowloaded file as:

  • BKDR_BLYPT.B
  • BKDR64_BLYPT.B
  • BKDR_BLYPT.SM

  SOLUTION

Minimum Scan Engine: 9.300
FIRST VSAPI PATTERN FILE: 10.290.08
FIRST VSAPI PATTERN DATE: 21 Sep 2013
VSAPI OPR PATTERN File: 10.291.00
VSAPI OPR PATTERN Date: 21 Sep 2013

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

Remove malware/grayware files dropped/downloaded by BKDR_BLYPT.A

Step 3

Scan your computer with your Trend Micro product and note files detected as BKDR_BLYPT.A

Step 4

Restart in Safe Mode

[ Learn More ]

Step 5

Search and delete files detected as BKDR_BLYPT.A

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result.

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

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