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TUCoPS :: PC Hacks :: va1085.htm

IBM Lenovo BIOS Plain Text Password Disclosure



IBM Lenovo BIOS Plain Text Password Disclosure
IBM Lenovo BIOS Plain Text Password Disclosure



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[ iViZ Security Advisory 08-005                            25/08/2008 ]
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iViZ Techno Solutions Pvt. Ltd.
http://www.ivizsecurity.com 
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* Title:     IBM Lenovo BIOS Plain Text Password Disclosure
* Date:      25/08/2008
* Software:  IBM Lenovo BIOS

- --[ Synopsis:

    Like most BIOSes, IBM Lenovo's firmware 7CETB5WW v2.05  (10/13/2006)
    can be used to ask a password to users at boot time to implement a
    pre-boot authentication.

    The password checking routine of this firmware fails to sanitize the
    BIOS keyboard buffer after reading user input, resulting in plain
    text password leakage to local users.

- --[ Affected Software:

  * IBM Lenovo 7CETB5WW v2.05  (10/13/2006) BIOS
  (possibly others too)

- --[ Technical description:

    The BIOS's pre-boot authentication routines use the BIOS API to
    read user input via the keyboard. The BIOS internally copies the
    keystrokes in a RAM structure called the BIOS Keyboard buffer
    inside the BIOS Data Area. This buffer is not flushed after use,
    resulting in potential plain text password leakage once the OS
    is fully booted, assuming the attacker can read the password at
    physical memory location 0x40:0x1e.

- --[ Impact:

    Plain text password disclosure. Local access is required, but no
    physical access to the machine.

    The level of privilege required to retrieve the password from memory
    is OS dependent and varies from guest user under Microsoft Windows
    (any) to root user under most Unix based OSes.

- --[ Full Technical Whitepaper

http://www.ivizsecurity.com/research/preboot/preboot_whitepaper.pdf 

- --[ Vendor response:

  * No Response from vendor in spite of multiple solicitations.

- --[ Credits:

    This vulnerability was discovered by Security Researcher
    Jonathan Brossard from iViZ Techno Solutions Pvt. Ltd.

- --[ Disclosure timeline:

  * First private disclosure to vendor on July 15th 2008
  * First Public disclosure at Defcon 16 on August 10th 2008

- --[ Reference:

http://www.ivizsecurity.com/security-advisory.html 
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