BKDR_BLYPT.SM

October 23, 2013
 Analysis by: Jimelle Monteser
 ALIASES:

Trojan-Dropper.Win32.Injector (Ikarus), a variant of Win32/TrojanDownloader.Agent.RVK trojan (NOD32), Trojan.Win32.Generic!BT (Sunbelt), TrojanDropper.Injector (VBA32)

 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 arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites. It may be downloaded by other malware/grayware from remote sites.

It executes commands from a remote malicious user, effectively compromising the affected system. However, as of this writing, the said sites are inaccessible.

  TECHNICAL DETAILS

File Size:

89,600 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

23 Sep 2013

Payload:

Connects to URLs/IPs

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.

It may be downloaded by the following malware/grayware from remote sites:

  • BKDR_BLYPT.A

Installation

This backdoor adds the following folders:

  • %Application Data%\Microsoft\Crypto - hidden
  • %Application Data%\Microsoft\Crypto\RSA - hidden

(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.)

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 = "rundll32.exe %Application Data%\Microsoft\Crypto\NTCRYPT{variable}.tpl, Crypt"

Other System Modifications

This backdoor adds the following registry keys:

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\RunOnce

It adds the following registry entries:

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

HKEY_CURRENT_USER\Software\Microsoft\
SystemCertificates\CA\Certificates\
5A82739996ED9EBA18F1BBCDCCA62D2C1D670C
Blob02 = "{hex values}"

HKEY_CURRENT_USER\Software\Microsoft\
SystemCertificates\CA\Certificates\
5A82739996ED9EBA18F1BBCDCCA62D2C1D670C
Blob05 = "{hex values}"

Backdoor Routine

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

  • Download and Execute Files
  • Get System Information (OS Platform, Processor type and architecture)

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

  • {BLOCKED}.162.47
  • {BLOCKED}.162.45
  • {BLOCKED}.181.50

However, as of this writing, the said sites are inaccessible.

NOTES:
The .DLL file, %Application Data%\Microsoft\Crypto\RSA\ntcrypt{random}.TPL detected as BKDR_BLYPT.B is also downloaded by BKDR_BLYPT.A.

If the said .DLL file is not existing, this malware downloads the .DLL file and save it as %Application Data%\Microsoft\Crypto\NTCRYPT{variable}.TPL.

  SOLUTION

Minimum Scan Engine:

9.300

FIRST VSAPI PATTERN FILE:

10.296.04

FIRST VSAPI PATTERN DATE:

23 Sep 2013

VSAPI OPR PATTERN File:

10.297.00

VSAPI OPR PATTERN Date:

24 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

Restart in Safe Mode

[ Learn More ]

Step 3

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

Step 4

Remove malware/grayware files that dropped/downloaded BKDR_BLYPT.SM

Step 5

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\Windows\CurrentVersion
    • RunOnce
  • In HKEY_CURRENT_USER\Software\Microsoft\SystemCertificates\CA\Certificates
    • 5A82739996ED9EBA18F1BBCDCCA62D2C1D670C

Step 6

Search and delete this folder

[ 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.
  • Application Data%\Microsoft\Crypto

Step 7

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