SymbOS/Yxes.C!worm

Alias/esWorm:SymbOS/Yxe (F-Secure)
Release DateFeb 19, 2009
Detection Availability
Active DatabaseExtended Database
FortiGatelowhigh
FortiClient
FortiMailN/A
Current Antivirus Definition Database Version: 11.589
Description

Visible Symptoms

  • The repeated attempts by the worm to send SMS messages may yield:

    • Rapid battery power loss
    • Abnormally high phone bills

  • Presence of the following file:

    • C:\sys\bin\Transmitter.exe

Detailed Analysis

This worm is a variant of SymbOS/Yxes.A!worm, with which it shares some functionalities.

  • It is targeting mobile devices running SymbianOS S60 3rd Edition (eg: Nokia 3250), but may run on a wider range of devices, as it has been reported to run on phones operating SymbianOS S60 3rd edition FP 1 (eg: Nokia N73). It bears a valid certificate signed by Symbian, and as such, installs flawlessly on "normal" (i.e. not "cracked") mobile devices running S60 3rd Edition.

  • It harvests phone numbers from the infected device's contact list, and repeatedly attempts to send SMS messages to those. The messages feature a malicious Web address (aka a URL); upon "clicking" on this address in the received message, the recipients will effectively download a copy of the worm (provided their phones/subscriptions allow for internet browsing).


  • Technical details

  • Creates a global semaphore named TransmitterSemaphore_0x2001EB41.

  • Creates and/or modifies the following files:
    • C:\system\data\prg.ini
    • C:\private\2001EB41\prg.ini
    • C:\private\2001EB41\state.txt
    • C:\private\2001EB41\NumberFile.txt
    • C:\private\2001EB41\TipFile.txt
    • C:\private\2001EB41\PropertyFile.txt
    • C:\private\2001EB41\NumberIndex.txt
    • C:\private\2001EB41\IniNumberIndex.txt
  • Attempts to silently connect to the Internet.

  • Collects phone numbers from the device's contact list.

  • Attempts to send SMS messages to the list of numbers collected above; the messages feature a malicious internet link to a copy of the worm.

  • Description Last Updated Date: Aug 28, 2009
    Reference: ID - 755619