Threat Explorer

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22 January 2009
27 January 2009
Also Known As:
OSX/iWorkServ.A [F-Secure], OSX/IWService [McAfee], OSX/iWorkS-A [Sophos], OSX_KROWI.A [Trend], OSX/iWorkS-Fam [Sophos], OSX/Krowi.A [Computer Associates]
Infection Length:
413,568 bytes
Systems Affected:
OSX.Iservice is a Trojan horse that runs on Mac OS X and opens a back door on the compromised computer.

Note: Virus definitions dated January 23, 2009 or earlier may detect this threat as OSX.Iwork.

For more information, please read the following:
OSX.Iservice—It’s not going to iWork for you.

Antivirus Protection Dates

  • Initial Rapid Release version 22 January 2009 revision 025
  • Latest Rapid Release version 24 February 2009 revision 040
  • Initial Daily Certified version 22 January 2009 revision 040
  • Latest Daily Certified version 24 February 2009 revision 048
  • Initial Weekly Certified release date 28 January 2009
Click here for a more detailed description of Rapid Release and Daily Certified virus definitions.
The Trojan is shared through BitTorrent and is bundled with a modified copy of the iWork09 trial application.

The modified iWork09 installer has the following file name and is 472,275,848 bytes (450 MB) in size:

The bundle contains part of the legitimate iWork09 trial package and also the following malicious package:

When the installer is executed, it runs the following malicious program:

Note: The malicious file is a Universal Binary designed to run both on PowerPC and x86 architectures.

Next, the Trojan determines if the session is running with root privileges. If not, the threat exits.

The Trojan creates the following folder if it did not execute from the iWorkServices file:

It then attempts to delete the following file:

The Trojan copies itself as the following file:

It modifies the following files so that it runs every time the computer starts:
  • /System/Library/StartupItems/iWorkServices/iWorkServices
  • /System/Library/StartupItems/iWorkServices/StartupParameters.plist

Next, the Trojan restarts itself from the /System/Library/StartupItems/iWorkServices folder and decrypts its configuration file which is encrypted with the AES algorithm.

It then opens a back door on the compromised computer and may contact the following hosts in order to receive further commands from the remote attacker:

The remote attacker may use the following remote commands:
  • socks
  • system
  • httpget
  • httpgeted
  • rand
  • sleep
  • banadd
  • banclear
  • p2plock
  • p2punlock
  • nodes
  • leafs
  • unknowns
  • p2pport
  • p2pmode
  • p2ppeer
  • p2ppeerport
  • p2peertype
  • set
  • get
  • clear
  • abortall
  • p2pihistsize
  • p2pihist
  • platform
  • script
  • sendlogs
  • uptime
  • uid
  • shell
  • rshell

Note: The network traffic is encrypted with AES.


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.
The following instructions pertain to all current and recent Symantec antivirus products for Macintosh.
  1. Update the virus definitions.
  2. Run a full system scan and repair or delete all the files detected.
For specific details on each of these steps, read the following instructions.

1. To update 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.

2. To scan for and delete the infected files
a. Start your Norton AntiVirus for Macintosh program and make sure that it is configured to scan all the files.
b. Run a full system scan. For more information on how to do this, read the document, "How to install Norton AntiVirus for Macintosh ."
c. If any files are detected, click Repair (if available) or Delete.
Writeup By: Elia Florio