W32.Pinfi
Risk Level 1: Very Low
Discovered: October 11, 2001
Updated: February 13, 2007 11:42:23 AM
Also Known As: Win32.Parite.a [KAV], W32/Pate.a [McAfee], Win32.Pinfi.A [CA], PE_PARITE.A [Trend], W32/Parite-A [Sophos], Win32/Parite.A [RAV]
Type: Virus
Systems Affected: Windows 2000, Windows 95, Windows 98, Windows Me, Windows NT, Windows XP
SUMMARY
W32.Pinfi is a memory-resident polymorphic virus that will infect the .EXE and .SCR files. This virus can also spread via mapped drives and network shares.
Protection
* Initial Rapid Release version October 12, 2001
* Latest Rapid Release version October 30, 2007 revision 040
* Initial Daily Certified version October 12, 2001 revision 007
* Latest Daily Certified version November 1, 2007 revision 003
* Initial Weekly Certified release date October 17, 2001
Click here for a more detailed description of Rapid Release and Daily Certified virus definitions.
Threat Assessment
Wild
* Wild Level: Low
* Number of Infections: More than 1000
* Number of Sites: More than 10
* Geographical Distribution: High
* Threat Containment: Moderate
* Removal: Moderate
Damage
* Damage Level: Low
Distribution
* Distribution Level: Medium
TECHNICAL DETAILS
Upon executing a file infected with W32.Pinfi, the virus will perform the following:
1. Adds the registry value:
PINF
to the registry key:
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer
2. Appends itself to Explorer.exe to remain memory-resident.
3. Appends itself to all the .EXE and .SCR files that it finds on all the local and mapped drives. The virus contains an algorithm to slow the infection, so the virus will only infect a few files at a time.
4. W32.Pinfi will create a tempfile in the temporary folder. It will get the temporary folder by using a Windows API. The tempfile that this virus creates will always have the following name:
[3 random letters][4 random hexadecimal digits].tmp
The file that the virus creates is a UPX-packed executable file. The virus will execute the temporary file, and it is this file that will attempt to infect files over network shares.
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
The following instructions pertain to all current and recent Symantec antivirus products, including the Symantec AntiVirus and Norton AntiVirus product lines.
1. Disable System Restore (Windows Me/XP).
2. Update the virus definitions.
3. Restart the computer in Safe mode (Windows 95/98/Me/2000/XP) of VGA mode (Windows NT).
4. Run a full system scan and repair all the files detected as W32.Pinfi.
5. Reverse the value that the virus added to the registry.
For specific details on each of these procedures, read the following instructions.
1. Disabling System Restore (Windows Me/XP)
If you are running Windows Me or Windows XP, we recommend that you temporarily turn off System Restore. Windows Me/XP uses this feature, which is enabled by default, to restore the files on your computer in case they become damaged. If a virus, worm, or Trojan infects a computer, System Restore may back up the virus, worm, or Trojan on the computer.
Windows prevents outside programs, including antivirus programs, from modifying System Restore. Therefore, antivirus programs or tools cannot remove threats in the System Restore folder. As a result, System Restore has the potential of restoring an infected file on your computer, even after you have cleaned the infected files from all the other locations.
Also, a virus scan may detect a threat in the System Restore folder even though you have removed the threat.
For instructions on how to turn off System Restore, read your Windows documentation, or one of the following articles:
* "How to disable or enable Windows Me System Restore"
* "How to turn off or turn on Windows XP System Restore"
For additional information, and an alternative to disabling Windows Me System Restore, see the Microsoft Knowledge Base article, "Antivirus Tools Cannot Clean Infected Files in the _Restore Folder," Article ID: Q263455.
2. Updating the virus definitions
Symantec Security Response fully tests all the virus definitions for quality assurance before they are posted to our servers. There are two ways to obtain the most recent virus definitions:
* Running LiveUpdate, which is the easiest way to obtain virus definitions: These virus definitions are posted to the LiveUpdate servers once each week (usually on Wednesdays), unless there is a major virus outbreak. To determine whether definitions for this threat are available by LiveUpdate, refer to the Virus Definitions (LiveUpdate).
* Downloading the definitions using the Intelligent Updater: The Intelligent Updater virus definitions are posted on U.S. business days (Monday through Friday). You should download the definitions from the Symantec Security Response Web site and manually install them. To determine whether definitions for this threat are available by the Intelligent Updater, refer to the Virus Definitions (Intelligent Updater).
The Intelligent Updater virus definitions are available: Read "How to update virus definition files using the Intelligent Updater" for detailed instructions.
3. Restarting the computer in Safe mode or VGA mode
* For Windows 95, 98, Me, 2000, or XP users, restart the computer in Safe mode. For instructions, refer to the document, "How to start the computer in Safe Mode."
* For Windows NT 4 users, restart the computer in VGA mode.
4. Scanning for and repairing the infected files
1. Start your Symantec antivirus software and make sure that it is configured to scan all the files.
* For Norton AntiVirus consumer products: Read the document, "How to configure Norton AntiVirus to scan all files."
* For Symantec AntiVirus Enterprise products: Read the document, "How to verify that a Symantec corporate antivirus product is set to scan all files."
2. Run a full system scan.
3. If any files are detected as infected with W32.Pinfi, click Repair.
5. Reversing the value from the registry
CAUTION: Symantec strongly recommends that you back up the registry before you make any changes to it. Incorrect changes to the registry can result in permanent data loss or corrupted files. Modify the specified keys only. Read the document, "How to make a backup of the Windows registry," for instructions.
1. Click Start, and then click Run. (The Run dialog box appears.)
2. Type regedit, and then click OK. (The Registry Editor opens.)
3. Navigate to the key:
HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer
4. In the right pane, delete the value: PINF
5. Exit the Registry Editor.
|
)
