Analysis by: Rika Joi Gregorio
ALIASES:

Server-Proxy.Win32.3proxy(Ikarus)

 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 may be dropped by other malware.

As of this writing, the said sites are inaccessible.

It deletes itself after execution.

  TECHNICAL DETAILS

File Size: 169,472 bytes
File Type: DLL
Memory Resident: Yes
Initial Samples Received Date: 16 Oct 2013

Arrival Details

This backdoor may be dropped by other malware.

Installation

This backdoor drops the following copies of itself into the affected system:

  • %Application Data%\Microsoft\Crypto\RSA\-1131521333.dll

(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\Run
RSA-1131521333 = "%System%\rundll32.exe "%Application Data%\Microsoft\Crypto\RSA\-1131521333.dll", DllInitialize"

Download Routine

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

  • %User Temp%\86task1.dll

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.)

As of this writing, the said sites are inaccessible.

Other Details

This backdoor connects to the following possibly malicious URL:

  • http://{BLOCKED}8c7844dcd6ef01448f44c9.com:53/proxy/g.php
  • http://{BLOCKED}1bd7a716774f7350694b6fc.com:53/proxy/g.php
  • http://{BLOCKED}76fd9fa9c89a15b3bfda9b.com:53/proxy/g.php
  • http://{BLOCKED}1529e05aee2974b4f0e33f.com:53/cgi-bin/outside.cgi?{random value}
  • http://{BLOCKED}f01529e05aee2974b4f0e33f.com/cgi-bin/ldr.cgi?{random value}
  • {BLOCKED}.{BLOCKED}.172.142:53
  • {BLOCKED}.{BLOCKED}.85.89:1346
  • http://{BLOCKED}1529e05aee2974b4f0e33f.com:53/86task1.dll

It deletes itself after execution.

  SOLUTION

Minimum Scan Engine: 9.300
FIRST VSAPI PATTERN FILE: 10.358.06
FIRST VSAPI PATTERN DATE: 23 Oct 2013
VSAPI OPR PATTERN File: 10.359.00
VSAPI OPR PATTERN Date: 23 Oct 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

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
    • RSA-1131521333 = "%System%\rundll32.exe "%Application Data%\Microsoft\Crypto\RSA\-1131521333.dll", DllInitialize"

Step 4

Search and delete this file

[ 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.
  • %User Temp%\86task1.dll

Step 5

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


Did this description help? Tell us how we did.