BKDR_KELIHOS.XU

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 executes commands from a remote malicious user, effectively compromising the affected system. However, as of this writing, the said sites are inaccessible.

It steals certain information from the system and/or the user.

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.

Autostart Technique

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
SonyAgent = "{Malware Path and File Name}"

Backdoor Routine

This backdoor opens the following port(s) where it listens for remote commands:

• TCP Port 8888

It executes the following commands from a remote malicious user:

• Request spam email messages structure and template
• Send spam email messages
• Send stolen information
• Get operating system information
• Get drive information
• List running processes
• Download and execute arbitrary files
• Update server with a list of compromised computers
• Manage registry

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

• http://{BLOCKED}.{BLOCKED}.125.202
• http://{BLOCKED}.{BLOCKED}.3.44
• http://{BLOCKED}.{BLOCKED}.126.36
• http://{BLOCKED}.{BLOCKED}.213.115
• http://{BLOCKED}.{BLOCKED}.151.66
• http://{BLOCKED}.{BLOCKED}.146.193
• http://{BLOCKED}.{BLOCKED}.85.59
• http://{BLOCKED}.{BLOCKED}.77.137
• http://{BLOCKED}.{BLOCKED}.118.45
• http://{BLOCKED}.{BLOCKED}.176.93
• http://{BLOCKED}.{BLOCKED}.52.41
• http://{BLOCKED}.{BLOCKED}.31.126
• http://{BLOCKED}.{BLOCKED}.220.220
• http://{BLOCKED}.{BLOCKED}.90.1
• http://{BLOCKED}.{BLOCKED}.90.66
• http://{BLOCKED}.{BLOCKED}.37.72
• http://{BLOCKED}.{BLOCKED}.92.152
• http://{BLOCKED}.{BLOCKED}.167.216
• http://{BLOCKED}.{BLOCKED}.29.133
• http://{BLOCKED}.{BLOCKED}.143.26
• http://{BLOCKED}.{BLOCKED}.201.30
• http://{BLOCKED}.{BLOCKED}.114.72
• http://{BLOCKED}.{BLOCKED}.30.45
• http://{BLOCKED}.{BLOCKED}.192.34
• http://{BLOCKED}.{BLOCKED}.180.37
• http://{BLOCKED}.{BLOCKED}.217.14
• http://{BLOCKED}.{BLOCKED}.112.38

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

Information Theft

This backdoor steals the following information:

• Network traffic information
• Login credentials from FTP, POP3 and SMTP traffic
• Digital currency

NOTES:

This backdoor modifies its file attributes into read-only and hidden after execution.

It exchanges encrypted messages with a remote server via HTTP protocol (TCP port 80). It uses this crafted User-Agent when communicating with the remote host:

Mozilla/5.0 (Windows; U; Windows NT; rv:1.9.2.17) Gecko/20110420 Firefox/3.6.17

It also installs WinPcap, a legitimate and commonly used Windows packet capture library to monitor the infected computer's network activities by dropping and installing the following files:

• %System%\packet.dll - non-malicious
• %System%\wpcap.dll - non-malicious
• %System%\drivers\npf.sys - non-malicious

It sends spam email messages using Simple Mail Transfer Protocol (SMTP) connection. It harvests email addresses from the affected computer's local drive.

It checks the presence of the following applications in the affected computer and attempts to steal login credentials and digital currency:

• 32-bit FTP
• Bitcoin
• BitKinex
• Bullet Proof FTP
• BulletProof FTP Client
• Classic FTP
• Core FTP
• CoreFTP
• CuteFTP
• Directory Opus
• FAR Manager
• FFFTP
• FTP Commander
• FTP Commander Deluxe
• FTP Commander Pro
• FTP Control
• FTP Explorer
• FTP Navigator
• FTPRush
• FileZilla
• FlashFXP
• Fling
• Fling FTP
• Frigate3
• Frigate3 FTP
• LeapFTP
• NetDrive
• SecureFX
• SmartFTP
• SoftX FTP Client
• Sota FFFTP
• Total Commander
• TurboFTP
• UltraFXP
• WS_FTP
• WebDrive
• WebSitePublisher
• WinSCP