W32.Rahack.W

The worm creates the following registry subkey:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MSWindows

The worm also creates the following registry entry if it runs on Windows 9x:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\RunServices\"MSWindows" = "%System%\dmhelpserver.exe"

Next, it copies itself as the following file:
%System%\urdvxc.exe

The worm attempts to inject code into the following process:
Explorer.exe

The worm searches for the following .dll files under HKEY_CLASSES_ROOT\CLSID:

• browseui.dll
• fm20.dll
• mshtml.dll
• ole32.dll
• oleaut32.dll
• sdocvw.dll
• shell32.dll
• thumbvw.dll

The worm then creates the file %System%\[RANDOM].dll and replaces registry entries under the following registry subkey with the name of the .dll file:
HKEY_CLASSES_ROOT\CLSID

Alternatively, the worm may create the following registry subkey:
HKEY_CLASSES_ROOT\CLSID\[RANDOM_CLSID]

The worm searches for .htm or .html files on the compromised computer. If they are found, the worm creates an executable file with a random name, and modifies the .htm file to run the executable file every time an .html file is opened.

The worm then creates a service with the following properties:
Service Name: MSWindows
Display Name: Network Windows Service

The worm attempts to access remote computers running Radmin on TCP port 9988, using the following passwords:

• 00
• 000
• 0000
• 00000
• 000000
• 0000000
• 00000000
• 1
• 12
• 123
• 1234
• 12345
• 123456
• 1234567
• 12345678
• 123456789
• Admin
• X
• abc123
• access
• adm
• alpha
• anon
• anonymous
• asdfgh
• backdoor
• backup
• beta
• bin
• coffee
• computer
• crew
• database
• debug
• default
• demo
• go
• guest
• hello
• install
• internet
• login
• mail
• manager
• money
• monitor
• network
• new
• newpass
• nick
• nobody
• nopass
• oracle
• pass
• passwd
• password
• poiuytre
• private
• public
• qwerty
• random
• real
• remote
• root
• ruler
• secret
• secure
• security
• server
• setup
• shadow
• shit
• sql
• super
• sys
• system
• telnet
• temp
• test
• test1
• test2
• visitor
• windows

The worm attempts to access remote Windows shares on TCP ports 139 and 445 by exploiting the above list of weak passwords and using the following standard Windows usernames:

• ASPNET
• Administrator
• DHCP
• HelpAssistants
• HelpServicesGroup
• ILS_[GROUP-USER]
• IUSR_[GROUP-USER]
• IWAM_[GROUP-USER]
• NetShowServices
• OWS_[GROUP-USER]
• POP3
• SQL
• SQLAgentCmdExec
• SQLDebugger
• SQLServer
• SUPPORT_388945a0
• TelnectClients
• TsInternetUser
• VUSR
• WEB
• WINS

The worm copies itself onto the remote computer as the following file and attempts to execute itself:
C:\temp.exe

It may generate ICMP traffic and ping requests on the local network in order to discover attackable remote machines.

The threat attempts to contact the following remote locations:

• www.if.ee - using TCP port 80
• www.online.if.ee - using TCP port 443 and encrypted traffic
• www.starman.ee - using TCP port 80

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