Vulnerability identifier: #VU22277

Vulnerability risk: Low

CVSSv3.1: 6.1 [CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2019-16905

CWE-ID: CWE-190

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 integer overflow within the XMSS key parsing algorithm. A local user can configure the server or client to use a specially crafted XMSS private key, trigger integer overflow and execute arbitrary code on the target system with elevated privileges.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

OpenSSH: 7.8p1 - 8.0p1

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External links
http://0day.life/exploits/0day-1009.html
http://bugzilla.suse.com/show_bug.cgi?id=1153537
http://cvsweb.openbsd.org/cgi-bin/cvsweb/src/usr.bin/ssh/sshkey-xmss.c
http://cvsweb.openbsd.org/cgi-bin/cvsweb/src/usr.bin/ssh/sshkey-xmss.c.diff?r1=1.5&r2=1.6&f=h
http://security.netapp.com/advisory/ntap-20191024-0003/
http://ssd-disclosure.com/archives/4033/ssd-advisory-openssh-pre-auth-xmss-integer-overflow
http://www.openssh.com/releasenotes.html
http://www.openwall.com/lists/oss-security/2019/10/09/1

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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.