Ubuntu update for openssh

Published: 2024-01-03 | Updated: 2024-04-19

Risk	Medium
Patch available	YES
Number of vulnerabilities	3
CVE-ID	CVE-2021-41617 CVE-2023-51384 CVE-2023-51385
CWE-ID	CWE-269 CWE-326 CWE-78
Exploitation vector	Network
Public exploit	Public exploit code for vulnerability #3 is available.
Vulnerable software	Ubuntu Operating systems & Components / Operating system openssh-server (Ubuntu package) Operating systems & Components / Operating system package or component openssh-client (Ubuntu package) Operating systems & Components / Operating system package or component
Vendor	Canonical Ltd.

Security Bulletin

This security bulletin contains information about 3 vulnerabilities.

1) Improper Privilege Management

EUVDB-ID: #VU58333

Risk: Low

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

CVE-ID: CVE-2021-41617

CWE-ID: CWE-269 - Improper Privilege Management

Exploit availability: No

Description

The vulnerability allows a local user to escalate privileges.

The vulnerability exists due to improper privilege management in sshd, when certain non-default configurations are used, because supplemental groups are not initialized as expected. Helper programs for AuthorizedKeysCommand and AuthorizedPrincipalsCommand may run with privileges associated with group memberships of the sshd process, if the configuration specifies running the command as a different user. A local user can escalate privileges on the system.

Mitigation

Update the affected package openssh to the latest version.

Vulnerable software versions

Ubuntu: 20.04 - 23.10

openssh-server (Ubuntu package): before 1:8.2p1-4ubuntu0.11

openssh-client (Ubuntu package): before 1:8.2p1-4ubuntu0.11

CPE2.3

External links

https://ubuntu.com/security/notices/USN-6565-1

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.

2) Inadequate Encryption Strength

EUVDB-ID: #VU84792

Risk: Low

CVSSv4.0: 1.7 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:U/U:Clear]

CVE-ID: CVE-2023-51384

CWE-ID: CWE-326 - Inadequate Encryption Strength

Exploit availability: No

Description

The vulnerability allows a remote attacker to gain access to sensitive information.

The vulnerability exists due to an error in the ssh-agent, which causes certain destination constraints to be incompletely applied. When destination constraints are specified during addition of PKCS#11-hosted private keys, these constraints are only applied to the first key, even if a PKCS#11 token returns multiple keys.

Mitigation

Update the affected package openssh to the latest version.

Vulnerable software versions

Ubuntu: 20.04 - 23.10

openssh-server (Ubuntu package): before 1:8.2p1-4ubuntu0.11

openssh-client (Ubuntu package): before 1:8.2p1-4ubuntu0.11

CPE2.3

External links

https://ubuntu.com/security/notices/USN-6565-1

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

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

3) OS Command Injection

EUVDB-ID: #VU84789

Risk: Medium

CVSSv4.0: 6.6 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:P/U:Green]

CVE-ID: CVE-2023-51385

CWE-ID: CWE-78 - Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')

Exploit availability: Yes

Description

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

The vulnerability exists due to improper input validation when processing user names, if a user name or host name has shell metacharacters, and this name is referenced by an expansion token in certain situations. A remote attacker can execute arbitrary OS commands via an untrusted Git repository.

Mitigation

Update the affected package openssh to the latest version.

Vulnerable software versions

Ubuntu: 20.04 - 23.10

openssh-server (Ubuntu package): before 1:8.2p1-4ubuntu0.11

openssh-client (Ubuntu package): before 1:8.2p1-4ubuntu0.11

CPE2.3

External links

https://ubuntu.com/security/notices/USN-6565-1

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability. However, proof of concept for this vulnerability is available.