BKDR_COBEACON.B

 Analysis by: Nikko Tamana

 PLATFORM:

Windows

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: Yes

  • 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.

It opens random ports. It executes commands from a remote malicious user, effectively compromising the affected system.

  TECHNICAL DETAILS

File Size:

4911366 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

21 Dec 2017

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 files:

  • %User Temp%\_MEI2802\Crypto.Cipher._AES.pyd
  • %User Temp%\_MEI2802\MSVCR100.dll
  • %User Temp%\_MEI2802\_bz2.pyd
  • %User Temp%\_MEI2802\_ctypes.pyd
  • %User Temp%\_MEI2802\_hashlib.pyd
  • %User Temp%\_MEI2802\_lzma.pyd
  • %User Temp%\_MEI2802\_socket.pyd
  • %User Temp%\_MEI2802\_ssl.pyd
  • %User Temp%\_MEI2802\df_newc2_stageless.exe.manifest
  • %User Temp%\_MEI2802\pyexpat.pyd
  • %User Temp%\_MEI2802\python34.dll
  • %User Temp%\_MEI2802\select.pyd
  • %User Temp%\_MEI2802\unicodedata.pyd
  • %User Temp%\_MEI2802\Include\pyconfig.h
  • %User Temp%\_MEI2802\base_library.zip

(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:

  • %User Temp%\_MEI2802
  • %User Temp%\_MEI2802\Include

(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.)

Backdoor Routine

This Backdoor opens a random port to allow a remote user to connect to the affected system. Once a successful connection is established, the remote user executes commands on the affected system.

It executes the following commands from a remote malicious user:

  • Set sleep time
  • Execute shell command
  • Execute PowerShell command using Powershell
  • Execute PowerShell cmdlets without powershell.exe
  • Execute PowerShell command by injecting to a specific process
  • Execute command from a specific directory
  • Spawn session for listener
  • Spawn specific architecture and full path to a program to spawn
  • Inject a session into a specific process
  • Inject a 64-bit version of malware to a 64-bit process
  • Inject Reflective DLL into a process
  • Inject a shellcode from a local file into a specific process
  • Inject a shellcode into a spawned process
  • Assign alternate parent process
  • Execute command with another process as the parent
  • Spawn a session with another process as the parent
  • Download file/s
  • Display files currently being downloaded
  • Upload file/s
  • List files in current directory
  • Create new folder
  • Delete file/folder
  • Copy file/s
  • Move file/s
  • Log keystrokes
  • Take screenshots
  • Display currently executing backdoor command
  • Terminate currently executing backdoor command
  • Setup SOCKS4a proxy server
  • Setup reverse pivot
  • Disable reverse port forward
  • List privilege escalation exploits
  • Perform exploit to elevate privilege
  • Execute command using known credentials
  • Spawn session using known credentials
  • Impersonate a token for the SYSTEM account
  • Spawn a session in a process with elevated rights
  • Enable privileges assigned to current access token
  • Execute Mimikatz to recover user logon passwords
  • Scan ports
  • Enumerate network and hosts
  • Impersonate a token from an existing process
  • Inject a Kerberos ticket into the current session
  • Execute a payload on a remote host
  • Execute a payload on a remote host using PowerShell
  • Execute a payload on a remote host using WinRM
  • Deliver payload via Windows Management Instrumentation
  • Terminate itself
  • Terminate a process
  • Modify timestamps

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

  • https://rcb{BLOCKED}pspot.com/___utm.gif?utmac=UA-2202604-2&utmcn=1&utmcs=ISO-8859-1&utmsr=1280x1024&utmsc=32-bit&utmul=en-US

As of this writing, the said servers are currently inaccessible.

Other Details

This Backdoor connects to the following URL(s) to check for an Internet connection:

  • http://www.google.com:443
  • http://mail.google.com:443
  • http://docs.google.com:443

  SOLUTION

Minimum Scan Engine:

9.850

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

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.
  • %User Temp%\_MEI2802

Step 4

Scan your computer with your Trend Micro product to delete files detected as BKDR_COBEACON.B. 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 the following Trend Micro Support pages for more information:


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