Technology, Support, and News Forum

[pres butan]

whenever i put XP on my comp, i always notice that ive got the sasser virus ''lsass' and some other virus 'crss' how can i remove these without connectiing to the internet to get a virus removal tool???

[phileysmiley]

Microsoft teams have confirmed that the Sasser worm (W32.Sasser.A and its variants) is currently circulating on the Internet. Microsoft has verified that the worm exploits the Local Security Authority Subsystem Service (LSASS)

http://www.microsoft.com/technet/securi ... 4-011.mspx

[phileysmiley]

From McAfee:

Manual Removal Instructions
To remove this virus "by hand", follow these steps:

Reboot the system into Safe Mode (hit the F8 key as soon as the Starting Windows text is displayed, choose Safe Mode.
Delete the file AVSERVE2.EXE from your WINDOWS directory (typically c:\windows or c:\winnt)
Edit the registry
Delete the "avserve2" value from
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
Reboot the system into Default Mode
Sniffer Customers
Filters have been developed that will look for Sasser traffic [Sniffer Distributed 4.1/4.2/4.3, Sniffer Portable 4.7/4.7.5, and Netasyst].

SnifferFilter - W32_SasserWorm.zip
McAfee Intrushield
This worm is detected in all Intrushield signauture sets 1.5.37.5, 1.8.27.2, 1.9.8.2 and later. In the IntruShield Alert Viewer, you would see the following alert when Sasser worm propagation is detected:

DCERPC: Microsoft Windows LSASS Buffer Overflow (0x47601c00)
Customers with in-line deployment should configure the sensor response of the above signature action to block in the policies.

McAfee System Compliance Profiler
Create a rule to match a registry key

Select HKEY_LOCAL_MACHINE from the drop-down box
In the field after the drop-down box, enter in the path Software\Microsoft\Windows\CurrentVersion\Run
For Value name, enter avserve2.exe
In the next drop-down box, select "Registry value does not exist"
McAfee Desktop Firewall
To prevent possibly remote access McAfee Desktop Firewall users can block incoming TCP port(s) 5554, 9996

McAfee Threatscan
ThreatScan signatures that can detect the W32/Sasser.worm.b virus are available from:

Threatscan 2.5 - ftp.nai.com/pub/security/tsc25/updates/winnt
Threatscan 2.0/2.1 - ftp.nai.com/pub/security/tsc20/updates/winnt
ThreatScan Signature version: 2004-05-03

ThreatScan users can detect the virus by running a ThreatScan task using the following settings:

Select the "Remote Infection Detection" category and "Windows Virus Checks" template.
-or-
Select the "Other" category and "Scan All Vulnerabilities" template.
For additional information:

Run the "ThreatScan Template Report"
Look for module number #4073

ThreatScan users can detect the remote access component by running a Resource Discovery Task using the following settings:

Select TCP Port scan
Enter ports 5554,9996

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[phileysmiley]

From Symantec:


Manual Removal
The following instructions pertain to all current and recent Symantec antivirus products, including the Symantec AntiVirus and Norton AntiVirus product lines.

End the malicious process (Windows NT/2000/XP).
Disable System Restore (Windows XP).
Update the virus definitions.
Run a full system scan and delete all the files detected as W32.Sasser.Worm.
Reverse the change made to the registry.

For details on each of these steps, read the following instructions.

1. To end the malicious process
On Windows NT/2000/XP computers, you must first end the malicious process. Follow these instructions:
Press Ctrl+Alt+Delete once.
Click Task Manager.
Click the Processes tab.
Double-click the Image Name column header to alphabetically sort the processes.
Scroll through the list and look for the following processes:
avserve.exe
any process with a name consisting of four or five digits, followed by _up.exe (for example, 74354_up.exe).
If you find any such process, click it, and then click End Process.
Exit the Task Manager.

2. To disable System Restore (Windows XP)
If you are running Windows XP, we recommend that you temporarily turn off System Restore. Windows 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 "How to turn off or turn on Windows XP System Restore"

--------------------------------------------------------------------------------
Note: When you are completely finished with the removal procedure and are satisfied that the threat has been removed, re-enable System Restore by following the instructions in the aforementioned documents.
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3. To update 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.

4. To scan for and delete the infected files
Start your Symantec antivirus program 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."
Run a full system scan.
If any files are detected as infected with W32.Sasser.Worm, click Delete.

5. To reverse the change made to the registry


--------------------------------------------------------------------------------
WARNING: Symantec strongly recommends that you back up the registry before making 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.
--------------------------------------------------------------------------------

Click Start, and then click Run. (The Run dialog box appears.)
Type regedit

Then click OK. (The Registry Editor opens.)


Navigate to the key:

HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run


In the right pane, delete the value:

"avserve.exe"="%Windir%\avserve.exe"


Exit the Registry Editor.





Revision History:

[txcougar03 Profile]

I didn't think "lsass" and "csrss" were viruses but you said crss so that could be one but I thought the other 2 processes were legit

[phileysmiley]

LSASS and CRSS can be legit, but LSASS is definitely exploited by the Sasser worm (see 2nd post above). CRSS is probably legit but can be exploited, too.
_________________________________________________________

Stack-based buffer overflow in certain Active Directory service functions in LSASRV.DLL of the Local Security Authority Subsystem Service (LSASS) in Microsoft Windows NT 4.0 SP6a, 2000 SP2 through SP4, XP SP1, Server 2003, NetMeeting, Windows 98, and Windows ME, allows remote attackers to execute arbitrary code via a packet that causes the DsRolerUpgradeDownlevelServer function to create long debug entries for the DCPROMO.LOG log file, as exploited by the Sasser worm.
__________________________________________________
CRSS
What is it?
Client/Server Runtime Server Subsystem

What does it do?
This is the user-mode portion of the Win32 subsystem (with Win32.sys being the kernel-mode portion). Csrss stands for client/server run-time subsystem and is an essential subsystem that must be running at all times. Csrss is responsible for console windows, creating and/or deleting threads, and some parts of the 16-bit virtual MS-DOS environment.

[txcougar03 Profile]

Well I just thought what he said sounded funny because it sounded like it was off of a fresh install and he thought he had a virus

[imnuts Profile Website]

both of those are system services and i don't think they can be completely removed as i think they are essential for running xp properly.

[marathonman]

"lsass" and "csrss" aren't viruses in themselves, no. I'm pretty sure I've seen them on fresh installs.

[imnuts Profile Website]

they aren't viruses themselves, but i think there are a few viruses that exploit vulnerabilities in them. it may be possible to disable the services that use these, but i don't think you can get rid of all of the services without problems.