KORGO.Z según Symantec
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32.Korgo.Z
Discovered on: July 27, 2004
Last Updated on: July 28, 2004 01:45:27 PM
W32.Korgo.Z is a worm that attempts to propagate by exploiting the Microsoft Windows PCT Buffer Overrun Vulnerability (described in Microsoft Security Bulletin MS04-011) on TCP port 113. Previous Korgo variants used a different vulnerability, the LSASS Buffer Overrun Vulnerability.
Also Known As: WORM_KORGO.AC[Trend], Worm.Win32.Padobot.gen[Kaspersky], Win32.Korgo.AC[CA]
Variants: W32.Korgo.Y
Type: Worm
Infection Length: 9,359 bytes
Systems Affected: Windows 2000, Windows 95, Windows 98, Windows Me, Windows NT, Windows Server 2003, Windows XP
Systems Not Affected: DOS, Linux, Macintosh, Macintosh OS X, Novell Netware, OS/2, UNIX
Virus Definitions (Intelligent Updater) *
July 28, 2004
Virus Definitions (LiveUpdate™) **
August 04, 2004
*
Intelligent Updater definitions are released daily, but require manual download and installation.
Click here to download manually.
**
LiveUpdate virus definitions are usually released every Wednesday.
Click here for instructions on using LiveUpdate.
Wild
Number of infections: 0 - 49
Number of sites: 0 - 2
Geographical distribution: Low
Threat containment: Easy
Removal: Easy
Threat Metrics
Wild:
Low
Damage:
Medium
Distribution:
Medium
Damage
Payload Trigger: n/a
Payload: n/a
Large scale e-mailing: n/a
Deletes files: n/a
Modifies files: n/a
Degrades performance: Network propagation routines may degrade overall network performance.
Causes system instability: n/a
Releases confidential info: Backdoor functionality allows unauthorized access.
Compromises security settings: Backdoor functionality may compromise security settings.
Distribution
Subject of email: n/a
Name of attachment: n/a
Size of attachment: n/a
Time stamp of attachment: n/a
Ports: TCP port 445 and a random port.
Shared drives: n/a
Target of infection: Unpatched computers vulnerable to the Microsoft LSASS Windows exploit.
When W32.Korgo.Z is executed, it does the following:
Deletes the file, ftpupd.exe, from the folder in which the worm was executed.
Creates the mutex "uterm19.2" to ensure that only one instance of the worm is executed on the computer:
Creates the following mutexes:
u10
u10x
u11
u11x
u12
u12x
u13
u13i
u13x
u14
u14x
u15
u15x
u16
u16x
u17
u17x
u18
u18x
u19
u8
u9
Deletes the values:
avserve.exe
avserve2.exeUpdate Service
Bot Loader
Disk Defragmenter
MS Config v13
System Restore Service
SysTray
Windows Security Manager
Windows Update
Windows Update Service
WinUpdate
from the registry key:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
Copies itself as %System%\<random filename>.exe.
Note: %System% is a variable. The worm locates the System folder and copies itself to that location. By default, this is C:\Windows\System (Windows 95/98/Me), C:\Winnt\System32 (Windows NT/2000), or C:\Windows\System32 (Windows XP).
Adds the values:
"Client"="1"
"ID"="<random value>"
to the registry key:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Wireless
Adds the value:
"Cryptographic Service"="%System%\<random filename>.exe"
to the registry key:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
Attempts to inject a function into Explorer.exe as a thread.
If successful, this threat will continue to run in the Explorer.exe process. All of the worm's subsequent actions will appear to be done by Explorer.exe, and the worm will not show when viewing the process list in the Windows Task Manager.
If unsuccessful, the worm will continue to run as its own process.
Opens a random TCP port, which the worm uses to send itself.
Attempts to connect and update itself from one of the following IRC servers:
0AB1cvv.ru
adult-empire.com
asechka.ru
citi-bank.ru
color-bank.ru
crutop.nu
fethard.biz
filesearch.ru
kavkaz.tv
kidos-bank.ru
konfiskat.org
master-x.com
mazafaka.ru
parex-bank.ru
roboxchange.com
xware.cjb.net
The worm joins a channel and waits for commands, including a command to download and execute a file from a Web server.
Attempts to exploit the Microsoft Windows PCT Buffer Overrun Vulnerability (described in Microsoft Security Bulletin MS04-011), against random IP addresses. If the worm successfully finds a vulnerable computer, the computer will attempt to reconnect to the infected computer to download the worm.
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.
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.
Before you begin
If you are running Windows 2000 or XP, and have not yet done so, you must patch for the vulnerability. Microsoft Security Bulletin MS04-011 describes this process. If you do not, it is likely that your computer will continue to be re-infected.
The following instructions pertain to all current and recent Symantec antivirus products, including the Symantec AntiVirus and Norton AntiVirus product lines.
Disable System Restore (Windows Me/XP).
Update the virus definitions.
Restart the computer in Safe mode or VGA mode.
Run a full system scan and delete all the files detected as W32.Korgo.Z.
Reverse the changes made to the registry.
For details on each of these steps, read the following instructions.
1. To disable 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"
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.
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. 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.
3. To restart the computer in Safe mode or VGA mode
Shut down the computer and turn off the power. Wait for at least 30 seconds, and then restart 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, read the document, "How to start the computer in Safe Mode."
For Windows NT 4 users, restart the computer in VGA mode.
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.Korgo.Z, click Delete.
5. To reverse the changes made to the registry
Important: 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 > Run.
Type regedit
Then click OK.
Navigate to the key:
HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
In the right pane, delete the value:
"Microsoft Update Service"="%System%\<random filename>.exe"
Navigate to the key:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Wireless
In the right pane, delete the values, if they exist:
"Client"="1"
"ID" = "<random value>"
Exit the Registry Editor.
Restart the computer in Normal mode. For instructions, read the section on returning to Normal mode in the document, "How to start the computer in Safe Mode."
Write-up by: Kevin Ha
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Mañana amploaremos la informacion
De momento, conocer si existencia y como siempre, parches actualizados, t antivirus al día.
saludos
ms, 28-07-2004
msc hotline sat Virus Research Engineer