ISS Security Brief: UPDATED Sobig.F Mass-Email Worm - Trojan Horse Functionality

From: X-Force (
Date: 08/22/03

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    Internet Security Systems Security Brief
    August 22, 2003

    Sobig.F Mass-Email Worm - Trojan Horse Functionality


    The latest variant in the "Sobig" family, Sobig.F is propagating
    aggressively across the Internet. Sobig.F is propagating via email only,
    and it is not related to the recent spate of Internet worms. Sobig.F
    employs some new techniques to attempt to evade anti-virus software, and
    infected computers may be controlled by external third-parties. It
    contains hidden functionality that attempts to download and execute a file
    at a specific time.


    Aggressive propagation of mass-email worms have been known to cause
    localized email outages due to the load placed on email servers. Sobig.F
    contains backdoor code which may allow the author or originator of the worm
    to control infected computers. This may allow the author to steal
    information, run specific Trojan horse programs, or install unsolicited
    email (Spam) relays. The new file payload is currently unknown as the virus
    receives a URL to the new file at a certain time (3:00pm EDT).

    For the complete ISS X-Force Security Alert, please visit:


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