Remote code execution in OpenSSH client

1) Double Free

EUVDB-ID: #VU51444

Risk: Medium

CVSSv4.0: 4.4 [CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2021-28041

CWE-ID: CWE-415 - Double Free

Exploit availability: No

Description

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

The vulnerability exists due to a boundary error in ssh-agent. A remote attacker can trick the victim to connect to a server, where the attacker has root privileges, pass specially crafted data to the ssh client, trigger a double free error and execute arbitrary code on the target system.

Successful exploitation of this vulnerability may result in complete compromise of vulnerable system.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

OpenSSH: 8.2p1 - 8.4p1

CPE2.3

• cpe:2.3:a:openssh:openssh:8.2p1:*:*:*:*:*:*:*
• cpe:2.3:a:openssh:openssh:8.3p1:*:*:*:*:*:*:*
• cpe:2.3:a:openssh:openssh:8.4p1:*:*:*:*:*:*:*

External links

http://github.com/openssh/openssh-portable/commit/e04fd6dde16de1cdc5a4d9946397ff60d96568db
http://www.openssh.com/security.html
http://www.openssh.com/txt/release-8.5
http://www.openwall.com/lists/oss-security/2021/03/03/1

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote authenticated user via the Internet.

How the attacker can exploit this vulnerability?

The attacker would have to send a specially crafted request to the affected application in order to exploit this vulnerability.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.