WORM_CRIDEX.OD
Worm:Win32/Cridex.E (Microsoft), Trojan.Win32.Cridex.tau (v) (Sunbelt), Trojan-Spy.Win32.Zbot.quwm (Kaspersky)
Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)
![](/vinfo/imgFiles/legend.jpg)
Threat Type: Worm
Destructiveness: No
Encrypted:
In the wild: Yes
OVERVIEW
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 deletes the initially executed copy of itself.
TECHNICAL DETAILS
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 and executes them:
- %User Profile%\Application Data\KB{8 random numbers}.exe
(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.)
It creates the following folders:
- %User Profile%\Application Data\{random string 1}
(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.)
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 number}.exe = "%User Profile%\Application Data\KB{random number}.exe"
Other System Modifications
This worm adds the following registry keys:
HKEY_CURRENT_USER\Software\Microsoft\
Windows NT\{random character}{random string 1}
HKEY_CURRENT_USER\Software\Microsoft\
Windows NT\{random string 2}
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings
GlobalUserOffline = "0"
Other Details
This worm connects to the following possibly malicious URL:
- http://{BLOCKED}srvr8.ru/{random characters}
- http://{BLOCKED}load.ru/{random characters}
- http://{BLOCKED}sdnl.ru/{random characters}
- http://{BLOCKED}ownloads17.ru/{random characters}
It deletes the initially executed copy of itself
SOLUTION
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
Restart in Safe Mode
Step 3
Delete this registry value
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{8 random numbers}.exe = "%User Profile%\Application Data\KB{8 random numbers}.exe"
- KB{8 random numbers}.exe = "%User Profile%\Application Data\KB{8 random numbers}.exe"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings
- GlobalUSerOffiline = "0"
- GlobalUSerOffiline = "0"
Step 4
Delete this registry key
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 NT
- {random character}{random string 1}
- {random character}{random string 1}
- In HKEY_CURRENT_USER\Software\Microsoft\Windows NT
- {random string 2}
- {random string 2}
Step 5
Search and delete this folder
Step 6
Restart in normal mode and scan your computer with your Trend Micro product for files detected as WORM_CRIDEX.OD. 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.
NOTES:
The created hidden folder %User Profile%\Application Data\{random string 1}, along with the created registry keys ;HKEY_CURRENT_USER\Software\Microsoft\Windows NT\{random character}{random string 1} and HKEY_CURRENT_USER\Software\Microsoft\Windows NT\{random string 2}, cannot be identified by the users since there are no reference values in the created folder or keys. The only way these folders/keys can be identified is by comparing the present folders/keys with a backup if the users have one. Note that these folders/keys need not to be deleted since it won't cause the user system any harm.
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