Symantec Security Response - W32.HLLW.Gaobot.AO © 1995-2003 Symantec Corporation. All rights reserved. Legal Notices Privacy Policy W32.HLLW.Gaobot.AO Discovered on: September 30, 2003 Last Updated on: October 01, 2003 11:22:26 AM W32.HLLW.Gaobot.AO 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 IRC. The worm uses multiple vulnerabilities to spread, including: The DCOM RPC vulnerability (described in Microsoft Security Bulletin MS03-026) using TCP port 135. The RPC locator vulnerability (described in Microsoft Security Bulletin MS03-001) using TCP port 445. The WebDav vulnerability (described in Microsoft Security Bulletin MS03-007) using TCP port 80. W32.HLLW.Gaobot.AO is compressed with UPX. Note: Virus definitions dated prior to October 1, 2003 may detect this as Hacktool. Type: Worm Infection Length: 207,872 bytes Systems Affected: Windows 2000, Windows NT, Windows XP Systems Not Affected: Linux, Macintosh, OS/2, UNIX, Windows 95, Windows 98, Windows Me Virus Definitions (Intelligent Updater) * October 01, 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: Moderate Threat Metrics Wild: LowDamage: MediumDistribution: Medium Damage Payload: Releases confidential info: Allows unauthorized remote access. Distribution Ports: 135, 445 Target of infection: Accounts with weak passwords; systems not patched against the DCOM RPC vulnerability or the RPC locator vulnerability. When W32.HLLW.Gaobot.AO runs, it does the following: Copies itself as %System%\regloadr.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 value: "Registry Loader"="regloadr.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 a hacker. Connects to a predefined IRC channel, using its own IRC client, and listens for the commands from a hacker. Allows a hacker to remotely control a compromised computer. This allows a hacker to perform any of the following actions: Manage the installation of the worm Dynamically update the installed worm Download and execute files Steal system information Send the worm to other IRC users Add new accounts 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 usernames and passwords, as well as any usernames found using NetUserEnum(): User: Admin Administrador Administrateur Administrator Default Dell Gast Guest Inviter Owner Standard Test User a aaa abc admin administrator asdf home mgmt pc qwer temp test win x xyz Password: 0 007 000000 00000000 1 110 111 111111 11111111 12 121212 123 123123 1234 12345 123456 1234567 12345678 123456789 1234qwer 123abc 123asd 123qwe 2002 2600 54321 654321 88888888 Internet Login Password a aaa abc abcd alpha computer database enable foobar god godblessyou home ihavenopass login love mypass mypc oracle owner pass passwd password pat patrick pc pw pwd root secret server sex super sybase temp test win xp xxx yxcv zxcv 8. Copies itself to any systems that it compromised using the aforementioned exploits. 9. Steals the CD keys of the following games: 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 Legends of Might and Magic Counter-Strike Half-Life 10. Ends the following processes that are associated with antivirus and firewall software: 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 F-PROT.EXE F-PROT95.EXE F-STOPW.EXE FINDVIRU.EXE FP-WIN.EXE FPROT.EXE FRW.EXE IAMAPP.EXE IAMSERV.EXE IBMASN.EXE IBMAVSP.EXE ICLOAD95.EXE ICLOADNT.EXE ICMON.EXE ICSUPP95.EXE ICSUPPNT.EXE IFACE.EXE IOMON98.EXE JEDI.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 _AVP32.EXE _AVPCC.EXE _AVPM.EXE 11. Attemps to kill some processes associated with other worms: dllhost.exe msblast.exe mspatch.exe penis32.exe scvhosl.exe tftpd.exe winhlpp32.exe winppr32.exe 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. Do one of the following: Windows 95/98/Me: Restart the computer in Safe mode. Windows NT/2000/XP: End the Trojan process. Run a full system scan and delete all the files detected as W32.HLLW.Gaobot.AO, or similar variants. Reverse the changes that the Trojan made to the registry. For 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" Note: When you are completely finished with the removal procedure, and you are satisfied that the threat has been removed, you should reenable 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. 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 ending the Trojan process Windows 95/98/Me Restart the computer in Safe mode. All the Windows 32-bit operating systems, except for Windows NT, can be restarted in Safe mode. For instructions, read the document, "How to start the computer in Safe Mode." Windows NT/2000/XP To end the Trojan process: 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 regloadr.exe. If you find the file, click it, and then click End Process. Exit the Task Manager. 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 W32.HLLW.Gaobot.AO, click Delete. 5. Reversing the changes 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 each of the keys: HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\ RunServices In the right pane, delete the value: "Registry Loader"="regloadr.exe" Exit the Registry Editor. Write-up by: Heather Shannon