Symantec Security Response - W32.HLLW.Gaobot.AN © 1995-2003 Symantec Corporation. All rights reserved. Legal Notices Privacy Policy W32.HLLW.Gaobot.AN Discovered on: September 29, 2003 Last Updated on: September 30, 2003 11:49:02 AM W32.HLLW.Gaobot.AN is a minor variant of W32.HLLW.Gaobot.AF. It attempts to spread to network shares that have weak passwords and allows attackers to access an infected computer through an IRC channel. The worm takes advantage of multiple vulnerabilities including: The DCOM RPC vulnerability (described in Microsoft Security Bulletin MS03-026) using TCP port 135. Using this exploit, the worm specifically targets Windows XP computers. The RPC locator vulnerability (described in Microsoft Security Bulletin MS03-001) using TCP port 445. W32.HLLW.Gaobot.AN is compressed with UPX. Also Known As: W32.HLLW.Gaobot.AF Type: Worm Infection Length: 208,386 bytes Systems Affected: Windows 2000, Windows NT, Windows Server 2003, Windows XP Systems Not Affected: DOS, Linux, Macintosh, OS/2, UNIX, Windows 3.x Virus Definitions (Intelligent Updater) * September 30, 2003 Virus Definitions (LiveUpdate™) ** October 01, 2003 *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: LowDamage: LowDistribution: Low When W32.HLLW.Gaobot.AF runs, it does the following: Copies itself as %System%\sycfg34.exe. Note: %System% is a variable. The worm locates the System folder and copies itself to that location. By default, this is C:\Winnt\System32 (Windows NT/2000) or C:\Windows\System32 (Windows XP). Adds the value: "Configuration Loader"="sycfg34.exe" to these registry keys: HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\RunServices so that the worm starts when Windows starts. Opens a randomly chosen TCP port to connect to the hacker. Connects to a predefined IRC channel, using its own IRC client, and listens for the commands from the hacker. When the worm runs, it allows the hacker to remotely control a compromised computer, which allows him/her to perform any of the following actions: Manage the installation of the worm Dynamically update the installed worm Download and execute files Steal the information of a compromised system Send the worm to other IRC users Add accounts for the hacker Sends data to TCP port 135, which exploits the DCOM RPC vulnerability, or sends data to TCP port 445 to exploit the RPC locator vulnerability. Probes the following shares admin$ c$ d$ e$ print$ using the following user/password combinations in addition to the user names found on the remote computer, as the NetUserEnum() API determines: User: Administrator admin administrator Administratur Default mgmt Standard User Administrador Owner Test Guest Gast Inviter a aaa abc x xyc Dell home pc test temp win asdf qwer login Password: admin Admin password Password 1 12 123 1234 12345 123456 1234567 12345678 123456789 654321 54321 111 000000 00000000 11111111 88888888 pass passwd database abcd oracle sybase 123qwe server computer Internet super 123asd ihavenopass godblessyou enable xp 2002 2003 2600 0 110 111111 121212 123123 1234qwer 123abc 007 alpha patrick pat administrator root sex god foobar a aaa abc test temp win pc asdf secret qwer yxcv zxcv home xxx owner login Login pwd pass love mypc mypass pw 8. After accessing vulnerable computers, the worm copies and executes itself on the new computers. 9. Steals the CD keys of the following games: Warcraft III Soldier of Fortune II - Double Helix Neverwinter Westwood\Nox Tiberian Sun Red Alert 2 Red Alert Project IGI 2 Command & Conquer Generals Battlefield 1942 Secret Weapons of WWII Battlefield 1942 The Road to Rome Battlefield 1942 Rainbow Six III RavenShield Nascar Racing 2003 Nascar Racing 2002 NHL 2003 NHL 2002 FIFA 2003 FIFA 2002 Need For Speed Hot Pursuit 2 The Gladiators Unreal Tournament 2003 LoMaM Counter-Strike Half-Life 10. Inventories the active processes and, if the name of the firewall and antivirus process is one of the following, the worm attempts to terminate it: _avp32.exe _avpcc.exe _avpm.exe Ackwin32.exe Anti-trojan.exe Apvxdwin.exe Autodown.exe Avconsol.exe Ave32.exe Avgctrl.exe Avkserv.exe Avnt.exe Avp.exe Avp32.exe Avpcc.exe Avpdos32.exe Avpm.exe Avptc32.exe Avpupd.exe Avsched32.exe Avwin95.exe Avwupd32.exe Blackd.exe Blackice.exe Cfiadmin.exe Cfiaudit.exe Cfinet.exe Cfinet32.exe Claw95.exe Claw95cf.exe Cleaner.exe Cleaner3.exe Dvp95.exe Dvp95_0.exe Ecengine.exe Esafe.exe Espwatch.exe F-agnt95.exe Findviru.exe Fprot.exe F-prot.exe F-prot95.exe Fp-win.exe Frw.exe F-stopw.exe Iamapp.exe Iamserv.exe Ibmasn.exe Ibmavsp.exe Icload95.exe Icloadnt.exe Icmon.exe Icsupp95.exe Icsuppnt.exe Iface.exe Iomon98.exe edi.exe Lockdown2000.exe Lookout.exe Luall.exe Moolive.exe Mpftray.exe N32scanw.exe Navapw32.exe Navlu32.exe Navnt.exe Navw32.exe Navwnt.exe Nisum.exe Nmain.exe Normist.exe Nupgrade.exe Nvc95.exe Outpost.exe Padmin.exe Pavcl.exe Pavsched.exe Pavw.exe Pccwin98.exe Pcfwallicon.exe Persfw.exe Rav7.exe Rav7win.exe Rescue.exe Safeweb.exe Scan32.exe Scan95.exe Scanpm.exe Scrscan.exe Serv95.exe Smc.exe Sphinx.exe Sweep95.exe Tbscan.exe Tca.exe Tds2-98.exe Tds2-nt.exe Vet95.exe Vettray.exe Vscan40.exe Vsecomr.exe Vshwin32.exe Vsstat.exe Webscanx.exe Wfindv32.exe Zonealarm.exe 11. Attemps to kill all the running processes that other worms have dropped: mspatch.exe penis32.exe msblast.exe scvhosl.exe winhlpp32.exe tftpd.exe dllhost.exe winppr32.exe 12. May attempt to perform a Denial of Service (DoS) attack. 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. 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. Reverse the changes that the worm made to the registry and restart the computer. Run a full system scan and delete all the files detected as W32.HLLW.Gaobot.AN. For specific details on each of these steps, 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. Reversing the changes made to the registry, restarting the computer 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: "Configuration Loader"="sycfg34.exe" Navigate to the key: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\RunServices In the right pane, delete the value: "Configuration Loader"="sycfg34.exe" Exit the Registry Editor. Restart the computer. 4. Scanning for and deleting 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.HLLW.Gaobot.AN, click Delete. Write-up by: Robert X Wang