Security Advisories

Intel BIOS Plain Text Password Disclosure

Synopsis

Like most BIOSes, Intel's firmware PE94510M.86A.0050.2007.0710.1559 (07/10/2007) 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

Intel Corp PE94510M.86A.0050.2007.0710.1559 (07/10/2007) 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 dependant and varies from guest user under Microsoft Windows (any) to root user under most Unix based OSes.

Full Technical Whitepaper

Technical Whitepaper

Patch Description

Read the detailed fix description

Vendor Response

Intel Product Security Incident Response Team (iPSIRT) has acknowledged the vulnerability and is proactively working on a fix.

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 vendor reply on July 15th 2008
CERT assigns tracker VU#604539 to the bug.
First Public disclosure at Defcon 16 on August 10th 2008



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