W95.K32

SUMMARY

W95.K32 is a memory resident virus that infects Windows executables. This virus is not destructive but does contain a payload.

Threat Assessment

Wild

• Wild Level: Low
• Number of Infections: 0 - 49
• Number of Sites: 0 - 2
• Geographical Distribution: Low
• Threat Containment: Easy
• Removal: Easy

Damage

• Damage Level: Low
• Payload Trigger: February 19

Distribution

• Distribution Level: Low
• Target of Infection: Windows PE .exe files

TECHNICAL DETAILS

If the current date is February 19 and an infected file is executed, it will display a message box with the caption "nIgr0_lives_here!!!!" and the following message:

Virus K32 por nIgr0 ... "Hazlo o no lo hagas pero no lo intentes".

The virus uses Windows functions that are exported from KERNEL32.DLL. It searches for the following functions in memory:

• CreateFile
• SetFilePointer
• ReadFile
• WriteFile
• CloseHandle
• CreateProcessA
• GetModuleHandleA
• GetProcAddress

Then, it hooks CreateProcessA so that it can infect files that are executed. The virus writes itself into the copy of KERNEL32.DLL in memory.

During infection, the virus appends itself to the end of the file that was executed. The size of infected files will increase by 3030 bytes.

Recommendations

Symantec Security Response encourages all users and administrators to adhere to the following basic security "best practices":

• Turn off and remove unneeded services. By default, many operating systems install auxiliary services that are not critical, such as an FTP server, telnet, and a Web server. These services are avenues of attack. If they are removed, blended threats have less avenues of attack and you have fewer services to maintain through patch updates.
• If a blended threat exploits one or more network services, disable, or block access to, those services until a patch is applied.
• Always keep your patch levels up-to-date, especially on computers that host public services and are accessible through the firewall, such as HTTP, FTP, mail, and DNS services (for example, all Windows-based computers should have the current Service Pack installed.). Additionally, please apply any security updates that are mentioned in this writeup, in trusted Security Bulletins, or on vendor Web sites.
• Enforce a password policy. Complex passwords make it difficult to crack password files on compromised computers. This helps to prevent or limit damage when a computer is compromised.
• Configure your email server to block or remove email that contains file attachments that are commonly used to spread viruses, such as .vbs, .bat, .exe, .pif and .scr files.
• Isolate infected computers quickly to prevent further compromising your organization. Perform a forensic analysis and restore the computers using trusted media.
• Train employees not to open attachments unless they are expecting them. Also, do not execute software that is downloaded from the Internet unless it has been scanned for viruses. Simply visiting a compromised Web site can cause infection if certain browser vulnerabilities are not patched.

REMOVAL

To repair an infected system, reset the PC, and boot to a clean boot floppy. Then, run NAV to detect and repair infected files.