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F-Secure Malware Information Pages: Email-Worm:W32/Zhelatin.KC
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Summary
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Zhelatin.KC is a bot that communicates via Overnet P2P protocol and is mainly used to send spam.
It has rootkit functionalities that hide its presence in the infected system. |
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Disinfection
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Automatic Disinfection
Usually standalone malware (backdoors, worms, trojans, etc.) is automatically removed by F-Secure Anti-Virus (FSAV) starting from version 5.40. Malware files get automatically renamed by FSAV, so they can not be started any more. In some rare cases, when automatic disinfection is not possible, a user can select disinfection action by him/herself to make FSAV rename or delete an infected file. In some special cases, it is recommended to use specific disinfection tools provided by F-Secure. They can be downloaded from our ftp site:
ftp://ftp.f-secure.com/anti-virus/tools/
F-Secure Anti-Virus can be purchased from our webshop or from our authorised distributors. A trial version F-Secure Anti-Virus, limited to 30 days, can be downloaded from our website:
http://www.f-secure.com/download-purchase/
All the latest versions of FSAV can download anti-virus database updates automatically. However, these updates can be also downloaded and installed manually from our web or ftp sites:
http://www.f-secure.com/download-purchase/updates.shtml
Manual Disinfection
To manually disinfect standalone malware (backdoors, worms, trojans, etc.) it's usually enough to delete all infected files from a computer and to restart it. Active malware files are usually locked by operating system so different disinfection approaches are required for different operating systems.
Please note that manual disinfection is a risky process, so it is recommended only for advanced users.
If Windows 95, 98 and ME operating system is used, it is recommended to restart a computer from a bootable system diskette and to delete an infected file from command prompt. For example if a malicious file named ABC.EXE is located in Windows folder, it is usually enough to type the following command at command prompt:
DEL C:\WINDOWS\ABC.EXE
and to press Enter. After that an infected file will be gone. If Windows NT, 2000 or XP is used, a malicious file has to be renamed with a different extension (for example .VIR) and then a system has to be restarted. After restart a renamed malicious file will no longer be active and it can be easily deleted manually.
Malware Disinfection Tools
F-Secure provides disinfection tools for certain malware. These tools can be downloaded from this web page:
http://www.f-secure.com/download-purchase/tools.shtml
ftp://ftp.f-secure.com/anti-virus/tools/
Windows System Restore Issues
If Windows ME or XP is used, it is recommended to disable System Restore feature of these operating systems to prevent a computer from re-infection by an already removed malware. The fact is that System Restore feature of these operating systems might save an infected file into the special folder and copy it back to a hard drive it every time it's been renamed or deleted by F-Secure Anti-Virus or by a user. Instructions on how to disable System Restore feature are here:
Windows ME:
http://www.f-secure.com/v-descs/sfc_dis.shtml
Windows XP:
http://www.f-secure.com/v-descs/sfc_dis1.shtml
It is recommended to re-enable System Restore after disinfection in order to restore stable system configuration in the future, if any crash or incompatibility issue occurs.
Failed Disinfection
In some cases F-Secure Anti-Virus might not disinfect a system automatically. In this case please visit our Support pages:
http://support.f-secure.com/enu/home/virusproblem/howtoclean/ |
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Detailed Description
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Zhelatin.KC does the following upon initial installation:
- Disable Windows File Protection
- Creates a copy called %WindowsDirectory%\spooldr.exe
- Drop its rootkit component %SystemDirectory%\spooldr.sys
- Infects %SystemDirectory%\dllcache\tcpip.sys
- Exits current process
The other routines of the malware are continued after the infected system is rebooted.
The following is how the malware is launched during system startups:
- The infected tcpip.sys gets loaded by the OS
- The infected tcpip.sys loads spooldr.sys
- Spooldr.sys injects spooldr.exe to the explorer.exe process
Once loaded, spooldr.exe creates a file called spooldr.cfg which contains its initial list of peers in the current directory of the running process. Since it does not have its own process, it will take the current directory of explorer.exe instead. This usually leads to spooldr.cfg being created in the home directory of the current user. Additionally, Spooldr.sys hides all filenames that start with "spooldr" in the system, therefore you might not find the created files once the rootkit has been loaded.
The malware then tries to communicate with the other peers via the Overnet P2P protocol on how to proceed.The malware has the ability to do the following:
- Harvest email addresses but avoid those that contain certain strings
- Download messages to be use in spam
- Send spam emails
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F-Secure Corporation |
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Last Modified: October 15, 2007
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