CVE-2008-3895 in LILO
Summary
by MITRE
LILO 22.6.1 and earlier stores pre-boot authentication passwords in the BIOS Keyboard buffer and does not clear this buffer before and after use, which allows local users to obtain sensitive information by reading the physical memory locations associated with this buffer.
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Analysis
by VulDB Data Team • 10/08/2018
The vulnerability identified as CVE-2008-3895 affects the Linux Loader LILO version 22.6.1 and earlier implementations, presenting a critical security flaw in the pre-boot authentication mechanism. This issue stems from the improper handling of sensitive authentication data within the system's hardware-level memory structures, specifically the BIOS Keyboard buffer. The flaw represents a fundamental failure in information protection during the boot process, where authentication credentials are stored in a manner that exposes them to unauthorized access through physical memory inspection techniques.
The technical implementation of this vulnerability occurs when LILO processes pre-boot authentication passwords, storing them within the BIOS Keyboard buffer without proper sanitization procedures. This buffer, which serves as a temporary storage area for keyboard input data at the hardware level, retains the password information in a predictable memory location that remains accessible even after the authentication process completes. The root cause aligns with CWE-200, which addresses improper exposure of sensitive information, and specifically demonstrates weaknesses in information hiding and memory management practices during system boot sequences. The buffer is neither cleared before use nor after completion of the authentication process, creating persistent exposure windows for credential data.
The operational impact of this vulnerability extends beyond simple credential theft, as it provides attackers with direct access to authentication information that could be leveraged for system compromise. An attacker with local physical access to the target system can utilize memory dumping techniques to read the contents of the BIOS Keyboard buffer, thereby extracting stored passwords without requiring sophisticated exploitation methods. This weakness particularly affects systems where physical security controls are insufficient, as it eliminates the need for network-based attacks or complex exploitation techniques. The vulnerability operates at the pre-boot stage, making it particularly dangerous since it can be exploited before the operating system has a chance to implement its own security controls, and it aligns with ATT&CK technique T1547.001 which covers registry run keys and startup folder.
Mitigation strategies for this vulnerability require immediate implementation of both software and hardware-based solutions to address the fundamental design flaw in LILO's authentication handling. System administrators should upgrade to LILO versions 22.6.2 and later, where the buffer clearing functionality has been implemented to properly sanitize memory locations after authentication operations. Additionally, physical security measures must be strengthened to prevent unauthorized access to systems during boot processes, as the vulnerability is specifically exploitable through physical memory inspection. Organizations should also consider implementing memory protection mechanisms such as secure boot configurations and firmware-level protections that prevent unauthorized memory access during pre-boot stages. The vulnerability demonstrates the critical importance of proper information sanitization in all system components, particularly those operating at the hardware level where traditional software-based protections may be insufficient.