CVE-2023-51767

What it actually does

A single-bit flip in the integer 'authenticated' variable within mm_answer_authpassword allows an attacker to change its value and bypass authentication checks when row hammer is performed on common DRAM types.

Why it matters to the business

Local attackers sharing hardware with a victim could obtain unauthorized elevated access, increasing risk of compromise in multi-tenant or shared environments, though the vendor disputes responsibility for hardware-level weaknesses.

How an attack unfolds

An attacker with existing local user privileges on a co-located system uses row hammer techniques against DRAM to flip a targeted bit in the authenticated flag during an authentication attempt, resulting in successful bypass without valid credentials.

How to fix it

Upgrade OpenSSH beyond version 10.0 where possible; for affected packages apply the listed fixes including apache/mesos (GIT) at 612ec2c63a68b4d5b60d1d864e6703fde1c2a023 and org.apache.mesos/mesos (maven) at 1.5.1; evaluate hardware-level mitigations such as ECC memory.

How to confirm the fix worked

Confirm OpenSSH version exceeds 10.0, review process memory protections, and test authentication flows under simulated bit-flip conditions if feasible.

Typical attack path

1. Gain local user privileges on the target system
2. Identify memory layout of the OpenSSH process
3. Execute row hammer attack to flip a single bit in the authenticated variable
4. Initiate authentication request that succeeds due to the altered flag

How to detect it

Review authentication logs for unexpected successes from low-privileged accounts; examine system memory error reports or row hammer indicators, though specific artifacts are limited due to the hardware nature of the attack.

What your security team should do

• Evaluate local attack surface and co-location risks given the 1042 days since publication and stable low EPSS
• Prioritize upgrades to the specified fixed versions in dependent packages
• Consider platform memory integrity features as supplemental controls
• Monitor vendor statements regarding hardware responsibility disputes