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OSX.RSPlug.A

Risk Level 1: Very Low

Discovered:
October 31, 2007
Updated:
November 2, 2007 7:14:05 AM
Also Known As:
OSX/RSPlug-A [Sophos], OSX/Puper [McAfee]
Type:
Trojan
Infection Length:
Varies
Systems Affected:
Mac OS X
The threat may arrive on the compromised computer by being downloaded via browser exploits or social engineering.

Once executed, copies itself as the following files:
/Library/Internet Plug-Ins/plugins.settings
/Library/Internet Plug-Ins/sendreq

It also creates the following clean file:
/Library/Internet Plug-Ins/Mozillaplug.plugins

It modifies the the hosts' DNS servers to one of the following sets of IP addresses:
  • 85.255.115.58
  • 85.255.112.159


OR
  • 85.255.115.21
  • 85.255.112.151


OR
  • 85.255.115.116
  • 85.255.112.222


OR
  • 85.255.113.106
  • 85.255.112.85


OR
  • 85.255.115.117
  • 85.255.112.204


OR
  • 85.255.116.150
  • 85.255.112.148


It then updates crontab to run the following script:
/Library/Internet Plug-Ins/plugin.settings

Note: This script ensures the DNS server entries are reverted back to the above IP addresses if they are updated.

It then sends the CPU type, the User Identifier (UID), and the hostname to the following URL:
http://85.255.121.37

The Trojan then deletes the file /Library/Internet Plug-Ins/sendreq.

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.
Writeup By: Stuart Smith
Summary| Technical Details| Removal

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