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BKDR_KELIHOS.NAP
Malware type: Backdoor
Destructive: No
Platform: Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)
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 executes commands from a remote malicious user, effectively compromising the affected system.

Technical Details


File size: 242,176 bytes
File type: EXE
Memory resident: Yes
Initial samples received date: 07 Feb 2013
Payload: Connects to URLs/IPs, Steals information, Drops files, Collects system information

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 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}.165.213
  • http://{BLOCKED}.{BLOCKED}.254.8
  • http://{BLOCKED}.{BLOCKED}.171.3
  • http://{BLOCKED}.{BLOCKED}.145.158
  • http://{BLOCKED}.{BLOCKED}.82.85
  • http://{BLOCKED}.{BLOCKED}.82.86
  • http://{BLOCKED}.{BLOCKED}.192.204

Information Theft

This backdoor gathers the following data:

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

It attempts to steal stored account information used in the following installed File Transfer Protocol (FTP) clients or file manager software:

  • 32 Bit FTP
  • BitKinex
  • Bullet Proof FTP
  • BulletProof FTP Client
  • BulletProof FTP Client 2009
  • BulletProof FTP Client 2010
  • Classic FTP
  • Core FTP
  • CuteFTP
  • CuteFTP 6 Home
  • CuteFTP 6 Professional
  • CuteFTP 7 Home
  • CuteFTP 7 Professional
  • CuteFTP 8 Home
  • CuteFTP 8 Professional
  • CuteFTP Lite
  • CuteFTP Pro
  • Directory Opus
  • FAR Manager FTP
  • FFFTP
  • FTP Commander
  • FTP Commander Deluxe
  • FTP Commander Pro
  • FTP Control
  • FTP Explorer
  • FTP Navigator
  • FTPRush
  • Far
  • Far2
  • FileZilla
  • FlashFXP
  • Fling
  • Fling FTP
  • Frigate3 FTP
  • GPSoftware
  • GlobalSCAPE
  • Ipswitch
  • Leap FTP
  • NetDrive
  • SecureFX
  • SmartFTP
  • SoftX FTP Client
  • Sota FFFTP
  • Total Commander
  • TurboFTP
  • UltraFXP
  • WebDrive
  • WinSCP

NOTES:

This backdoor modifies its file attributes into Read-only and Hidden after execution.

It also installs WinPcap, a legitimate and commonly used Windows packet capture library, which is used 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 exchanges encrypted messages with a remote server via HTTP protocol (TCP port 80). It uses the following 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 sends spam email messages using Simple Mail Transfer Protocol (SMTP) connection. It harvests email addresses from the affected computer's local drive.

Solution


Minimum scan engine: 9.300
First VSAPI Pattern File: 9.710.05
First VSAPI Pattern Release Date: 07 Feb 2013
VSAPI OPR Pattern Version: 9.711.00
VSAPI OPR Pattern Release Date: 08 Feb 2013

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

Scan your computer with your Trend Micro product and note files detected as BKDR_KELIHOS.NAP

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

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.
  • %System%\packet.dll
  • %System%\wpcap.dll
  • %System%\drivers\npf.sys

Step 6

Search and delete the file detected as BKDR_KELIHOS.NAP

[ Learn more ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden files in the search result.

Step 7

Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_KELIHOS.NAP. 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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Analysis By: Rhena Inocencio

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