[Full-disclosure] [IVIZ-08-005] IBM Lenovo BIOS Plain Text Password Disclosure

From: iViZ Security Advisories <advisories_at_nospam>
Date: Mon Aug 25 2008 - 09:09:06 GMT
To: bugtraq@securityfocus.com, full-disclosure@lists.grok.org.uk

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----------------------------------------------------------------------- [ iViZ Security Advisory 08-005 25/08/2008 ]
----------------------------------------------------------------------- iViZ Techno Solutions Pvt. Ltd. http://www.ivizsecurity.com
-----------------------------------------------------------------------
- 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:

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