SB2023020247 - Multiple vulnerabilities in OpenSSH

Description

This security bulletin contains information about 2 secuirty vulnerabilities.

1) Double Free (CVE-ID: CVE-2023-25136)

The vulnerability allows a remote attacker to potentially execute arbitrary code on the target system.

The vulnerability exists due to a boundary error within the sshd(8) daemon. A remote non-authenticated attacker can send  specially crafted data to the application, trigger a double free error and execute arbitrary code on the target system.

The vendor believes exploitation of this vulnerability has limitations as double free occurs "in the unprivileged pre-auth process that is subject to chroot(2) and is further sandboxed on most major platforms". Nevertheless we assign a high risk to this vulnerability.

2) Security features bypass (CVE-ID: N/A)

The vulnerability allows a remote attacker to bypass implemented security restrictions.

The vulnerability exists due to a logic error when parsing the PermitRemoteOpen option. The PermitRemoteOpen option would ignore its first argument unless it was one of the special keywords "any" or "none", causing the permission list to fail open if only one permission was specified.

Remediation

Install update from vendor's website.

References

• https://www.openssh.com/releasenotes.html#9.2
• https://github.com/openssh/openssh-portable/commit/486c4dc3b83b4b67d663fb0fa62bc24138ec3946
• https://bugzilla.mindrot.org/show_bug.cgi?id=3522