OSX.Leap.A

SUMMARY

OSX.Leap.A is a worm that targets installs of Macintosh OS X and spreads via iChat Instant Messenger program.

Note: It infects files on the Macintosh OS X version 10.4. The worm will execute on Intel Macs, but cannot spread to other systems from these machines.

Protection

• Virus Definitions (LiveUpdate™ Daily) February 16, 2006
• Virus Definitions (LiveUpdate™ Weekly) February 22, 2006
• Virus Definitions (Intelligent Updater) February 16, 2006
• Virus Definitions (LiveUpdate™ Plus) February 16, 2006

Threat Assessment

Wild

• Wild Level: Low
• Number of Infections: 0 - 49
• Number of Sites: 0 - 2
• Geographical Distribution: Low
• Threat Containment: Easy
• Removal: Easy

Damage

• Damage Level: Low

Distribution

• Distribution Level: Low
• Target of Infection: iChat Instant Messenger program.

TECHNICAL DETAILS

OSX.Leap.A arrives on the computer as an attachment to the following iChat Instant Message:




When the recipient clicks save, the archive file is saved as latestpics.tgz:




If the user opens the archive, the file latestpics is created:




Once OSX.Leap.A is executed, it performs the following actions:

1. Displays the following message:
   
   
   
   
2. Creates the following files:
   
   
   • /tmp/latestpics
   • /tmp/latestpics.tgz
   • /tmp/latestpics.tar.gz
   • /tmp/hook
   • /tmp/apphook
   • /tmp/pic.gz
   • /tmp/apphook.tar
   • /tmp/pic
     
     
3. Deletes all files from the following folder:
   
   ~/Library/InputManagers
   
   
4. Copies /tmp/apphook to the following folder:
   
   ~/Library/InputManagers/apphook/apphook.bundle/Contents/MacOS
   
   so that it runs every time an application starts.
   
   
5. Uses Spotlight to search for the four most recently used applications this month, which do not require root permissions.
   
   
6. Searches these files for the extended attribute oompa. If it does not find this attribute, it will infect the selected files.
   
   
7. Infects the selected files by copying the contents of the data fork to the resource fork of the selected file, and then copying itself to the data fork of the selected file.
   
   Note: Due to a bug in the code, the infected files may be corrupted and may not run correctly.
   
   
8. Creates the extended attribute oompa and sets it to loompa.
   
   
9. Monitors all launched applications. Every time the iChat application is launched, the worm sends the file latestpics.tgz to all the iChat contacts.
   
   Note: Due to a bug in the code, the worm may corrupt the file so that it appears larger than it actually is, and it may not be sent successfully.

Recommendations

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 (for example, all Windows-based computers should have the current Service Pack installed.). Additionally, please apply any security updates that are mentioned in this writeup, in trusted Security Bulletins, or on vendor Web sites.
• 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.

REMOVAL

1. Delete the infected file

At the time of writing, the file infected by this worm has the following file name:

latestpics

Delete this file. If this file has not been executed, no further action should be necessary.

2. Delete any associated files and restart the compromised computer

If the infected file has been executed, delete the following file:

/Users/[CURRENT USER]/Library/InputManagers/apphook.bundle

The compromised computer must then be restarted to remove the infection from memory.

Note:

• [CURRENT USER] is the name of the user who was logged in when the infected file was executed.
• The worm may infect other applications. If you suspect that an application has been compromised, it should be replaced from a clean backup copy.