Analysis by: RonJay Kristoffer Caragay
ALIASES:

Backdoor.Telebot (Symantec); Python/Agent.AE (ESET-NOD32); Backdoor.Python.Tele.a (Kaspersky)

 PLATFORM:

Windows

 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

This backdoor may be downloaded from remote sites by other malware.

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: 5,345,919 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 28 Dec 2016
Payload: Connects to URLs/IPs, Compromises system security

Arrival Details

This backdoor may be downloaded from remote site(s) by the following malware:

Installation

This backdoor adds the following folders:

  • %User Temp%\_MEI{random numbers}

(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 the following files:

  • %User Temp%\_MEI{random numbers}\_ctypes.pyd
  • %User Temp%\_MEI{random numbers}\_hashlib.pyd
  • %User Temp%\_MEI{random numbers}\_socket.pyd
  • %User Temp%\_MEI{random numbers}\_ssl.pyd
  • %User Temp%\_MEI{random numbers}\bz2.pyd
  • %User Temp%\_MEI{random numbers}\Crypto.Cipher._AES.pyd
  • %User Temp%\_MEI{random numbers}\Crypto.Hash._SHA256.pyd
  • %User Temp%\_MEI{random numbers}\Crypto.Random.OSRNG.winrandom.pyd
  • %User Temp%\_MEI{random numbers}\Crypto.Util._counter.pyd
  • %User Temp%\_MEI{random numbers}\Microsoft.VC90.CRT.manifest
  • %User Temp%\_MEI{random numbers}\msvcm90.dll
  • %User Temp%\_MEI{random numbers}\msvcp90.dll
  • %User Temp%\_MEI{random numbers}\msvcr90.dll
  • %User Temp%\_MEI{random numbers}\{random filename}.exe.manifest
  • %User Temp%\_MEI{random numbers}\pyexpat.pyd
  • %User Temp%\_MEI{random numbers}\python27.dll
  • %User Temp%\_MEI{random numbers}\pywintypes27.dll
  • %User Temp%\_MEI{random numbers}\requests\cacert.pem
  • %User Temp%\_MEI{random numbers}\select.pyd
  • %User Temp%\_MEI{random numbers}\unicodedata.pyd
  • %User Temp%\_MEI{random numbers}\win32api.pyd
  • %User Temp%\_MEI{random numbers}\win32pipe.pyd
  • %User Temp%\_MEI{random numbers}\win32wnet.pyd

(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.)

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
FlashPlayerPlugin = "%User Temp%\lsass.exe"

Backdoor Routine

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

  • up - Download File
  • ss - Take screenshot
  • logout - Log out
  • cmd - Executes shell command w/ feedback
  • cmdd - Executes shell command w/o feedback
  • getdoc - Upload any specified files from affected system
  • forcecheckin - Get OS information
  • time - Set sleep time
  • getphoto - Upload specified photo from affected system

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

  • https://{BLOCKED}i.{BLOCKED}ram.org/bot{token}/{api_name}?{param}
    where:
    {token} - bot user ID of telegram.org
    {api_name} - it use any of the following API names of telegram.org:
    • sendMessage
    • sendDocument
    • sendPhoto
    • getFile
    • getUpdates
    {param} - parameters needed of API (may not exist)

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

Download Routine

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

  • %User Temp%\~JF{random}.dat ← updated copy of itself

(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.)

Information Theft

This backdoor gathers the following data:

  • OS Platform Version
  • Process Architecture
  • Admintrator Privileges

Other Details

This backdoor drops the following file(s)/component(s):

  • %User Temp%\~DT{random}.txt ← log file; deleted afterwards

(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.)

  SOLUTION

Minimum Scan Engine: 9.800
FIRST VSAPI PATTERN FILE: 13.122.08
FIRST VSAPI PATTERN DATE: 29 Dec 2016
VSAPI OPR PATTERN File: 13.123.00
VSAPI OPR PATTERN Date: 29 Dec 2016

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

Remove the malware/grayware file that dropped/downloaded BKDR_TELEBOT.A. (Note: Please skip this step if the threat(s) listed below have already been removed.)

    • TROJ_DLOAD.TEYJQ

Step 4

Restart in Safe Mode

[ Learn More ]

Step 5

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
    • FlashPlayerPlugin = "%User Temp%\lsass.exe"

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.  
  • %User Temp%\_MEI{random numbers}

Step 7

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%\~JF{random}.dat

Step 8

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

Step 9

Scan your computer with your Trend Micro product to delete files detected as BKDR_TELEBOT.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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