TROJ_CRIBIT.A

This threat, dubbed as BitCrypt, is a ransomware that steals funds from various cryptocurrency wallets.

To get a one-glance comprehensive view of the behavior of this Trojan, refer to the Threat Diagram shown below.

This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It deletes the initially executed copy of itself.

Arrival Details

This Trojan 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 Trojan drops the following copies of itself into the affected system and executes them:

• %Application Data%\{random}.exe

(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.)

It drops the following files:

• %Application Data%\bitcrypt.ccw - configuration file
• %Application Data%\BitCrypt.txt - contains ransom message

(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.)

It leaves text files that serve as ransom notes containing the following:

Autostart Technique

This Trojan adds the following registry entries to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
Bitcomint = "%Application Data%\{random}.exe"

Other System Modifications

This Trojan adds the following registry keys as part of its installation routine:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
FileExts\.ccw

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
FileExts\.ccw\OpenWithList

It deletes the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Control\SafeBoot\Minimal

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Control\SafeBoot\Network

Process Termination

This Trojan terminates the following processes if found running in the affected system's memory:

• taskmgr.exe
• regedit.exe

Other Details

This Trojan encrypts files with the following extensions:

• *.abw
• *.arj
• *.asm
• *.bpg
• *.cdr
• *.cdt
• *.cdx
• *.cer
• *.css
• *.dbf
• *.dbt
• *.dbx
• *.dfm
• *.djv
• *.djvu
• *.doc
• *.docm
• *.docx
• *.dpk
• *.dpr
• *.frm
• *.jpeg
• *.jpg
• *.key
• *.lzh
• *.lzo
• *.mdb
• *.mde
• *.odc
• *.pab
• *.pas
• *.pdf
• *.pgp
• *.php
• *.pps
• *.ppt
• *.pst
• *.rtf
• *.sql
• *.text
• *.txt
• *.vbp
• *.vsd
• *.wri
• *.xfm
• *.xlc
• *.xlk
• *.xls
• *.xlsm
• *.xlsx
• *.xlw
• *.xsf
• *.xsn

It deletes the initially executed copy of itself

NOTES:

It queries the value of the following key which contains the Microsoft Geographical Location Value:

• HKEY_CURRENT_USER\Control Panel\International\Geo\Nation

The value is used as a part of the Bitcrypt ID.

It also executes the following commands:

• cmd.exe /K bcdedit /set {bootmgr} displaybootmenu no
• cmd.exe /K bcdedit /set {default} bootstatuspolicy ignoreallfailures

It appends the string bitcrypt to the encrypted file's extension.