* 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
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.