WORM_CRIDEX.TO
VirTool:Win32/CeeInject (Microsoft), W32.Cridex (Symantec), PWS-Zbot.gen.aou (McAfee)
Windows 2000, Windows XP, Windows Server 2003
![](/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 is injected into all running processes to remain memory resident.
It drops copies of itself in all removable drives.
It deletes the initially executed copy of itself.
TECHNICAL DETAILS
89,088 bytes
EXE
Yes
26 Oct 2012
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 number}.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 is injected into all running processes to remain memory resident.
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\C{8 random characters}
HKEY_CURRENT_USER\Software\Microsoft\
Windows NT\S{8 random characters}
It adds the following registry entries:
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings
GlobalUserOffline = "0"
Propagation
This worm drops copies of itself in all removable drives.
Other Details
This worm connects to the following possibly malicious URL:
- http://{BLOCKED}8.{BLOCKED}0.0.138/LvI/xCA/GoZZkCAAAA/Noy6SAAAA/
- http://{BLOCKED}1.{BLOCKED}5.83.189/LvI/xCA/GoZZkCAAAA/Noy6SAAAA/
- http://{BLOCKED}3.{BLOCKED}7.147.52/LvI/xCA/GoZZkCAAAA/Noy6SAAAA/
- http://{BLOCKED}7.{BLOCKED}2.144.115/LvI/xCA/GoZZkCAAAA/Noy6SAAAA/
- http://{BLOCKED}1.{BLOCKED}8.5.140/LvI/xCA/GoZZkCAAAA/Noy6SAAAA/
- http://{BLOCKED}0.{BLOCKED}6.23.100/LvI/xCA/GoZZkCAAAA/Noy6SAAAA/
- http://{BLOCKED}1.{BLOCKED}.235.35/LvI/xCA/GoZZkCAAAA/Noy6SAAAA/
- http://{BLOCKED}9.{BLOCKED}0.221.6/LvI/xCA/GoZZkCAAAA/Noy6SAAAA/
- http://{BLOCKED}8.{BLOCKED}8.2.214/LvI/xCA/GoZZkCAAAA/Noy6SAAAA/
- http://{BLOCKED}0.{BLOCKED}9.13.84/LvI/xCA/GoZZkCAAAA/Noy6SAAAA/
- http://{BLOCKED}1.{BLOCKED}1.168.98/LvI/xCA/GoZZkCAAAA/Noy6SAAAA/
- http://{BLOCKED}9.{BLOCKED}5.134.110/LvI/xCA/GoZZkCAAAA/Noy6SAAAA/
- http://{BLOCKED}3.{BLCOKED}8.208.55/LvI/xCA/GoZZkCAAAA/Noy6SAAAA/
- http://{BLOCKED}3.{BLOCKED}9.61.59/LvI/xCA/GoZZkCAAAA/Noy6SAAAA/
It deletes the initially executed copy of itself
SOLUTION
9.300
9.488.02
26 Oct 2012
9.489.00
27 Oct 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
Scan your computer with your Trend Micro product and note files detected as WORM_CRIDEX.TO
Step 3
Restart in Safe Mode
Step 4
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\Internet Settings
- GlobalUserOffline = "0"
- GlobalUserOffline = "0"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
- KB{random number}.exe = "%User Profile%\Application Data\KB{random number}.exe"
- KB{random number}.exe = "%User Profile%\Application Data\KB{random number}.exe"
Step 5
Search and delete the file detected as WORM_CRIDEX.TO
Step 6
Restart in normal mode and scan your computer with your Trend Micro product for files detected as WORM_CRIDEX.TO. 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 registry keys HKEY_CURRENT_USER\Software\Microsoft\Windows NT\S{8 random characters} and HKEY_CURRENT_USER\Software\Microsoft\Windows NT\C{8 random characters} cannot be identified by the users since there are no reference values in the created keys.
The only way these keys can be identified is by comparing the present keys with a backup if the users have one. Note that these keys need not be deleted since it won't cause the user system any harm.
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