Oss-sec post questions password authentication bypass in OpenSSH with musl libc

What happened and what to do

The post by Jacob Bachmeyer, published on 6 November on the oss-sec list, discusses the case called “sshole”, a bypass of password authentication in OpenSSH on systems using musl libc. The author asks whether the bypass works completely when no salt is available for reuse. He also points to a possible information leak: sshd might generate a “fake salt” or fail authentication quickly, revealing that no account on the machine has a valid password. This is a hypothesis raised in the discussion, with no technical confirmation in the text.

For a company, the practical point is to reduce exposed surface without relying on conclusions still under debate. On cloud virtual machine images reachable over SSH, password authentication should be disabled and replaced with keys, with a review of PasswordAuthentication, PermitRootLogin and unused accounts. In parallel, check whether the OpenSSH and C library versions in use are up to date according to vendor advisories, and monitor login attempts with telemetry that records timing and failure patterns to detect account enumeration. A pipeline collecting authentication logs with alerts and a per-host exposure dashboard makes the problem measurable.

How the consultancy can help

Diagnosis of SSH access exposure on servers and cloud images, covering authentication methods, OpenSSH and library versions and unused accounts. Then phased implementation: disabling passwords, key management, authentication log collection with alerts and a monitoring dashboard, operated in the client's environment.

Next step

Send a short description of your environment (systems, cloud images, SSH access methods and how logs are collected) and receive a scoped proposal for diagnosis and implementation.