BKDR_SIMBOT.SMJY

 Analysis by: Francis Xavier Antazo

 ALIASES:

Found Win32/DH{gRKBEyATADUiI1slA2EPgQ5kATZc} (AVG), a variant of Win32/Spy.Agent.OLK trojan (NOD32)

 PLATFORM:

Windows

 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.

  TECHNICAL DETAILS

File Size:

289,280 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

01 Oct 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%\Microsoft\MMC\mmc.exe

(Note: %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

It drops the following files:

  • %User Temp%\msiscatmp.tmp
  • %User Temp%\msisca.mof

(Note: %User Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

It drops and executes the following files:

  • %User Temp%\~{random 3 Characters}.tmp
  • %User Temp%\_uninsep.bat

(Note: %User Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

It creates the following folders:

  • %Application Data%\Microsoft\MMC\

(Note: %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

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
mmcupdate = "%Application Data%\Microsoft\MMC\mmc.exe -s"

Other Details

This backdoor connects to the following possibly malicious URL:

  • {BLOCKED}.{BLOCKED}.37.45
  • {BLOCKED}.{BLOCKED}.24.59/COOP1/upload.xmlupc.php
  • {BLOCKED}.{BLOCKED}.24.59/COOP1/upload/person/ana.php
  • {BLOCKED}.{BLOCKED}.24.59/COOP1/upload/xmlrpc.php
  • {BLOCKED}.{BLOCKED}.24.59/sites/all/modules/xmlrpc.php
  • {BLOCKED}.{BLOCKED}.14.220
  • {BLOCKED}.{BLOCKED}.13.169
  • {BLOCKED}.{BLOCKED}.72.29
  • {BLOCKED}.{BLOCKED}.96.154
  • {BLOCKED}.{BLOCKED}.253.146/sites/all/modules/xmlrpc.php
  • {BLOCKED}.{BLOCKED}.27.120/xampp/set.php
  • {BLOCKED}.{BLOCKED}.238.82

  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

Restart in Safe Mode

[ Learn More ]

Step 4

Search and delete these folders

[ 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\MMC\

Step 5

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%\~{random 3 Characters}.tmp
  • %User Temp%\_uninsep.bat
  • %User Temp%\msiscatmp.tmp
  • %User Temp%\msisca.mof

Step 6

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
    • mmcupdate = "%Application Data%\Microsoft\MMC\mmc.exe -s"

Step 7

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