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BKDR_ZYKLON.E

September 29, 2017
 Analysis by: Oliver Ramirez
 ALIASES:

Backdoor:MSIL/Omaneat.B (Microsoft); a variant of MSIL/Kryptik.JKS trojan (NOD32)

 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

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 logs a user's keystrokes to steal information.

  TECHNICAL DETAILS

File Size:

1,603,048 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

18 Jun 2017

Payload:

Logs keystrokes, Compromises system security

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 adds the following folders:

  • %Application Data%\tor

(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 copies of itself into the affected system:

  • %Application Data%\svchost.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:

  • %AppDataLocal%\GDIPFONTCACHEV1.DAT
  • %User Temp%\Tar{random}.tmp
  • %User Temp%\Cab{random}.tmp

(Note: %AppDataLocal% is the Application Data folder found in Local Settings, where it is usually C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local 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.. %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 adds the following mutexes to ensure that only one of its copies runs at any one time:

  • NHAOCXUxLC
  • VzkgNEUPxf
  • tLlRzFbFsl

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
winsched.exe = "%Application Data%\svchost.exe"

It drops the following file(s) in the Windows Startup folder to enable its automatic execution at every system startup:

  • %User Startup%\winsched.exe.vbs

(Note: %User Startup% is the current user's Startup folder, which is usually C:\Documents and Settings\{user}\Start Menu\Programs\Startup on Windows 2000 and XP, and C:\Documents and Settings\{User name}\Start Menu\Programs\Startup on Windows Vista, 7, and 8.)

Backdoor Routine

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

  • http://{BLOCKED}jpu7d55jh5.onion
  • http://{BLOCKED}dfrn2hbhci.onion
  • http://{BLOCKED}57cvdezbkc.onion

Information Theft

This Backdoor logs a user's keystrokes to steal information.

Other Details

This Backdoor does the following:

  • It terminates if the following processes exist on memory:
  • -sbiedll(Sandboxie)
  • -Fiddler

NOTES:

It has the capability to download additional plugins:

  • /update/index.php?update=y
  • /plugin/index.php?plugin=browser
  • /plugin/index.php?plugin=email
  • /plugin/index.php?plugin=ftp!
  • /plugin/index.php?plugin=software
  • /plugin/index.php?plugin=games
  • /plugin/index.php?plugin=cuda
  • /plugin/index.php?plugin=minerd
  • /plugin/index.php?plugin=sgminer
  • /plugin/index.php?plugin=socks

It has the capability to steal the following information using plugins:

  • Browser Password
  • E-mail Password
  • Ftp Password
  • Game and Software License Key
  • Crypto-currency Wallet

It has capability of executing following commands:

DDOS commands:

  • Http Get Flood
  • Http Post Flood
  • SYN Attack
  • TCP Attack

Remote Desktop (RDP) commands:

  • Show Desktop
  • Check Shell_TrayWnd
  • cmd.exe (command line shell)
  • taskmgr
  • explorer
  • runas

Plugin Related Commands:

  • start/stop miner
  • install/uninstall plugins
  • Uninstall -- Run
  • Uninstall -- RunOnce
  • Uninstall -- Script

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

13.652.05

FIRST VSAPI PATTERN DATE:

11 Sep 2017

VSAPI OPR PATTERN File:

13.653.00

VSAPI OPR PATTERN Date:

12 Sep 2017

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

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
    • winsched.exe "%Application Data%\svchost.exe"

Step 5

Search and delete these files

[ 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 Startup%\winsched.exe.vbs
  • %AppDataLocal%\GDIPFONTCACHEV1.DAT
  • %User Temp%\Tar{random}.tmp
  • %User Temp%\Cab{random}.tmp

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%\tor

Step 7

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