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WORM_CRIDEX.IC
Malware type: Worm
Destructive: No
Platform: Windows 2000, Windows XP, Windows Server 2003
Encrypted: No
In the wild: Yes

Overview


Infection Channel: Dropped by other malware, Downloaded from the Internet, Via removable drives, Propagates via removable drives

This malware intercepts browser requests and changes the displayed content according to the configuration, written by the administrator of the botnet. This way, cybercriminals can trick users into entering valuable information without raising suspicion. It was also found to generate several random domains using domain generating algorithms (DGA).

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

This worm arrives via removable drives. It 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 copies of itself into all the removable drives connected to an affected system. 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.

Technical Details


File size: 74,240 bytes
File type: EXE
Memory resident: Yes
Initial samples received date: 17 Mar 2012
Payload: Downloads files

Arrival Details

This worm arrives via removable drives.

It 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\E6D62C1B

(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 injects threads into the following normal process(es):

  • Explorer.exe

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 as part of its installation routine:

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

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows Media Center\4A5BC09B

HKEY_CURRENT_USER\Software\Microsoft\
Windows Media Center\E6D62C1B

Propagation

This worm drops copies of itself into all the removable drives connected to an affected system.

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={Malware File Name}.exe
shell\Open\Command={Malware File Name}.exe
shell\Open\Default=1
shell\Explore\Command={Malware File Name}.exe
shell\Autoplay\command={Malware File Name}.exe

Other Details

This worm deletes the initially executed copy of itself

NOTES:

This worm attempts to establish a connection to the following remote site:

  • http://{Random URL}.ru:8080/rwx/B2_9w3/in/

Once a successfully connected, this worm may download its configuration file from its C&C server.

This worm uses a domain generation algorithm to generate random domains.

Solution


Minimum scan engine: 9.200
First VSAPI Pattern File: 8.846.01
First VSAPI Pattern Release Date: 17 Mar 2012
VSAPI OPR Pattern Version: 8.847.00
VSAPI OPR Pattern Release Date: 18 Mar 2012

Step 1

For Windows XP and Windows Server 2003 users, before doing any scans, please make sure you disable System Restore to allow full scanning of your computer.

Step 2

Restart in Safe Mode

[ Learn more ]

Step 3

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
    • KB{Random Numbers}.exe = "%User Profile%\Application Data\KB{Random Numbers}.exe"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings
    • GlobalUserOffline = "0"

Step 4

Delete this registry key

[ 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. Before you could do this, you must restart in Safe Mode. For instructions on how to do this, you may refer to this page If the preceding step requires you to restart in safe mode, you may proceed to edit the system registry.

  • In HKEY_CURRENT_USER\Software\Microsoft\Windows Media Center
    • 4A5BC09B
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows Media Center
    • E6D62C1B

Step 5

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.
  • %User Profile%\Application Data\E6D62C1B

Step 6

Search and delete AUTORUN.INF files created by WORM_CRIDEX.IC that contain these strings

[ Learn more ]

[autorun]
open={Malware File Name}.exe
shell\Open\Command={Malware File Name}.exe
shell\Open\Default=1
shell\Explore\Command={Malware File Name}.exe
shell\Autoplay\command={Malware File Name}.exe

Step 7

Restart in normal mode and scan your computer with your Trend Micro product for files detected as WORM_CRIDEX.IC. 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: Michael Cabel

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