Backdoor.Autoupder

Backdoor.Autoupder initially presents itself as a Windows Cabinet (.cab) file named CoolStuff.cab. This file contains the ActiveX control file CoolStuff.ocx and the setup information file CoolStuff.inf. This file is usually obtained by visiting a malicious Web site that then attempts to download and install CoolStuff.cab to your computer. Currently, this is the only way that this Trojan is known to infect computers.

Once these files are installed, the ActiveX control checks the process list to see if any of the following programs are running:

• Blackice.exe (Black Ice Defender)
• Blackd.exe (Black Ice Defender)
• Zonealarm.exe (ZoneAlarm Firewall)
• Smc.exe (Sygate Personal Firewall)
• Persfw.exe (Tiny Personal Firewall)
• Lookout.exe (ISS Network Sniffer application)
• Espwatch.exe (Esafe Protect Watch)
• Mpftray.exe (McAfee Personal Firewall)
• Serv95.exe (Esafe Eliashim)
• Nisum.exe (Norton Internet Security)
• Nmain.exe (Norton Internet Security)

If any of these processes are running, Backdoor.Autoupder will terminate itself and do nothing. Otherwise, Backdoor.Autoupder will attempt to connect to one of the following Web sites, depending on its version:

• http:/ /www.online1net.com/
• http:/ /www.wwws1.com/au/

From one of the listed Web sites, Backdoor.Autoupder will try to download one or more of the following files and place them in the \Windows folder:

• Ausvc.exe: This module may also download malicious packages from one of the two listed Websites, and may install these packages on the victim's computer.
• Bvt.exe: This module is referred to as the Browser Event component. It appears to have listening functions which allow backdoor capabilities.
• Mnsvc.exe: This module connects to one of the two listed Websites, and checks if there are any new updated versions of the backdoor Trojan.
• Absr.exe: This module is referred to as the Auto Browser component. It appears to be trying to connect to any random Website.

It is possible that Backdoor.Autoupder will download other files instead. If one of the files has been downloaded successfully, Backdoor.Autoupder will terminate these processes if they are running, and execute the newly downloaded versions.

Upon execution of the downloaded executables, and depending on which file was executed, Backdoor.Autoupder adds one of the following values:

• SysScan C:\WINDOWS\bvt.exe
• ausvc C:\WINDOWS\ausvc.exe
• ABsr C:\WINDOWS\absr.exe
• mnsvc C:\WINDOWS\mnsvc.exe

to the registry key

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run

Backdoor.Autoupder may add one or more of the following subkeys:

{6541B981-2E27-46B1-A2CC-8264A75B74FE}
{868B015F-3515-44DB-B0AD-182CD058985E}
{9A05FE9B-5B52-4D13-A77D-FA7C38557A8E}
{BAE85C97-2CD4-45C3-A1ED-E4CEF7C6AA52}
{C76BE992-2BC3-41A4-8B87-A8C01FE419A7}
{F53C844A-D9C8-4E92-B923-C05B46C4A7E3}
{FBE091E5-DF43-4FFB-AECC-7E3A3BC7B0D9}

to the registry key:

HKEY_LOCAL_MACHINE\SOFTWARE\CLASSES\CLSID

It may add the following (or other) subkeys:

{8B034058-08B0-4CB3-B2E8-60238B4967F2}

to the registry key

HKEY_LOCAL_MACHINE\SOFTWARE\CLASSES\AppID

It may add the following (or other) subkeys:

{6D8B1B74-4AB8-473B-B479-253FA1936802}

to the following registry key:

HKEY_LOCAL_MACHINE\SOFTWARE\CLASSES\TypeLib

Backdoor.Autoupder is also capable of checking for the presence of newer versions of itself on specific Web sites and silently updating itself. Backdoor.Autoupder has strings embedded inside its program that may refer to commands used to remotely control the victim's computer.

Recommendations

Symantec Security Response encourages all users and administrators to adhere to the following basic security "best practices":

• Use a firewall to block all incoming connections from the Internet to services that should not be publicly available. By default, you should deny all incoming connections and only allow services you explicitly want to offer to the outside world.
• 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.
• Ensure that programs and users of the computer use the lowest level of privileges necessary to complete a task. When prompted for a root or UAC password, ensure that the program asking for administration-level access is a legitimate application.
• Disable AutoPlay to prevent the automatic launching of executable files on network and removable drives, and disconnect the drives when not required. If write access is not required, enable read-only mode if the option is available.
• Turn off file sharing if not needed. If file sharing is required, use ACLs and password protection to limit access. Disable anonymous access to shared folders. Grant access only to user accounts with strong passwords to folders that must be shared.
• Turn off and remove unnecessary services. By default, many operating systems install auxiliary services that are not critical. These services are avenues of attack. If they are removed, threats have less avenues of attack.
• If a 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.
• Configure your email server to block or remove email that contains file attachments that are commonly used to spread threats, such as .vbs, .bat, .exe, .pif and .scr files.
• Isolate compromised computers quickly to prevent threats from spreading further. 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.
• If Bluetooth is not required for mobile devices, it should be turned off. If you require its use, ensure that the device's visibility is set to "Hidden" so that it cannot be scanned by other Bluetooth devices. If device pairing must be used, ensure that all devices are set to "Unauthorized", requiring authorization for each connection request. Do not accept applications that are unsigned or sent from unknown sources.
• For further information on the terms used in this document, please refer to the Security Response glossary.

Summary