CVE-2019-6454 : Exploit Details and Defense Strategies

A vulnerability was found in systemd version 239, specifically in the sd-bus component, allowing an unauthorized local user to trigger a denial of service by manipulating the stack pointer. This could lead to a crash in systemd PID1 and subsequent kernel panic.

Understanding CVE-2019-6454

This CVE involves a vulnerability in systemd version 239, affecting the sd-bus component.

What is CVE-2019-6454?

CVE-2019-6454 is a vulnerability in systemd version 239, specifically in the sd-bus component. It allows an unauthorized local user to manipulate the stack pointer, leading to a denial of service.

The Impact of CVE-2019-6454

The exploitation of this vulnerability can result in a crash in systemd PID1 and trigger a kernel panic, causing a denial of service.

Technical Details of CVE-2019-6454

This section provides technical details about the vulnerability.

Vulnerability Description

The vulnerability exists in the function bus_process_object() in the file libsystemd/sd-bus/bus-objects.c, which uses a stack buffer of variable length to store the object path of incoming D-Bus messages.

Affected Systems and Versions

Affected Version: systemd 239

Exploitation Mechanism

An unauthorized local user can exploit this vulnerability by sending a specially crafted message to PID1, manipulating the stack pointer to jump beyond the stack guard pages into an unmapped memory region, resulting in a denial of service.

Mitigation and Prevention

To address CVE-2019-6454, follow these mitigation strategies:

Immediate Steps to Take

Apply patches provided by the vendor
Monitor vendor advisories for updates

Long-Term Security Practices

Regularly update and patch software
Implement the principle of least privilege

Patching and Updates

Update systemd to a non-vulnerable version