#VU1482 Use-after free in OpenSSH - CVE-2015-6564

Vulnerability identifier: #VU1482

Vulnerability risk: Low

CVSSv4.0: 9.3 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:A/U:Clear]

CVE-ID: CVE-2015-6564

CWE-ID: CWE-416

Exploitation vector: Local

Exploit availability: No

Vulnerable software:
OpenSSH
Server applications / Remote management servers, RDP, SSH

Vendor: OpenSSH

Description

The vulnerability allows a local user to escalate privileges on the system.

The vulnerability exists due to a use after free error within the mm_answer_pam_free_ctx() function in monitor.c in sshd daemon on non-OpenBSD platforms. A local unprivileged user can send an unexpected early MONITOR_REQ_PAM_FREE_CTX request and gain root privileges on the system.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

OpenSSH: 6.9p1

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External links
https://www.openssh.com/txt/release-7.0

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Q & A

Can this vulnerability be exploited remotely?

No. This vulnerability can be exploited locally. The attacker should have authentication credentials and successfully authenticate on the system.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability. However, a fully functional exploit for this vulnerability is available.