WORM_CRIDEX.DL

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

It drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system.

It deletes the initially executed copy of itself.

Arrival Details

This worm 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 worm drops the following copies of itself into the affected system:

• %User Profile%\Application Data\KB{random numbers}.exe

(Note: %User Profile% is the current user's profile folder, which is usually C:\Windows\Profiles\{user name} on Windows 98 and ME, C:\WINNT\Profiles\{user name} on Windows NT, and C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003.)

It creates the following folders:

• %User Profile%\Application Data\{random folder name 1}

(Note: %User Profile% is the current user's profile folder, which is usually C:\Windows\Profiles\{user name} on Windows 98 and ME, C:\WINNT\Profiles\{user name} on Windows NT, and C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003.)

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
KB{random numbers}.exe = "%User Profile%\Application Data\KB{random numbers}.exe"

Other System Modifications

This worm adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings
GlobalUserOffline = "0"

Propagation

This worm creates the following folders in all removable drives:

• {removable drive}\{random folder name 2}

It drops the following copy(ies) of itself in all removable drives:

• {random folder name 2}\{random file name}.exe

It drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system.

The said .INF file contains the following strings:

[autorun]
open={random folder name 2}\{random file name}.exe
shell\Open\Command={random folder name 2}\{random file name}.exe
shell\Open\Default=1
shell\Explore\Command={random folder name 2}\{random file name}.exe
shell\Autoplay\command={random folder name 2}\{random file name}.exe

Other Details

This worm connects to the following possibly malicious URL:

• http://{BLOCKED}.{BLOCKED}.87.172:8080/mx/6/B/in/
• http://{BLOCKED}.{BLOCKED}.168.98:8080/mx/6/B/in/
• http://{BLOCKED}.{BLOCKED}.203.140:8080/mx/6/B/in/
• http://{BLOCKED}.{BLOCKED}.221.6:8080/mx/6/B/in/
• http://{BLOCKED}.{BLOCKED}.23.100:8080/mx/6/B/in/
• http://{BLOCKED}.{BLOCKED}.5.140:8080/mx/6/B/in/
• http://{BLOCKED}.{BLOCKED}.12.158:8080/mx/6/B/in/
• http://{BLOCKED}.{BLOCKED}.122.8:8080/mx/6/B/in/
• http://{BLOCKED}.{BLOCKED}.0.138:8080/mx/6/B/in/
• http://{BLOCKED}.{BLOCKED}.41.155:8080/mx/6/B/in/
• http://{BLOCKED}.{BLOCKED}.144.115:8080/mx/6/B/in/
• http://{BLOCKED}.{BLOCKED}.42.98:8080/mx/6/B/in/
• http://{BLOCKED}.{BLOCKED}.144.158:8080/mx/6/B/in/
• http://{BLOCKED}.{BLOCKED}.76.102:8080/mx/6/B/in/

It deletes the initially executed copy of itself