Debian update for openssh

1) Improper Privilege Management

EUVDB-ID: #VU58333

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-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 openssh package to one of the following versions: 1:8.4p1-5+deb11u3, 1:9.2p1-2+deb12u2.

Vulnerable software versions

Debian Linux: All versions

openssh (Debian package): before 1:9.2p1-2+deb12u2

External links

http://www.debian.org/security/2023/dsa-5586

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) Credentials management

EUVDB-ID: #VU73775

Risk: Low

CVSSv3.1: 3.2 [CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N/E:U/RL:O/RC:C]

CVE-ID: CVE-2023-28531

CWE-ID: CWE-255 - Credentials Management

Exploit availability: No

Description

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

the vulnerability exists due to a logic error in ssh-add when adding smartcard keys to ssh-agent with the per-hop destination constraints. As a result, the keys are added without constraints.

Mitigation

Update openssh package to one of the following versions: 1:8.4p1-5+deb11u3, 1:9.2p1-2+deb12u2.

Vulnerable software versions

Debian Linux: All versions

openssh (Debian package): before 1:9.2p1-2+deb12u2

External links

http://www.debian.org/security/2023/dsa-5586

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) Inadequate encryption strength

EUVDB-ID: #VU84537

Risk: Low

CVSSv3.1: 3.2 [CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N/E:U/RL:O/RC:C]

CVE-ID: CVE-2023-48795

CWE-ID: CWE-326 - Inadequate Encryption Strength

Exploit availability: No

Description

The vulnerability allows a remote attacker to perform MitM attack.

The vulnerability exists due to incorrect implementation of the SSH Binary Packet Protocol (BPP), which mishandles the handshake phase and the use of sequence numbers. A remote attacker can perform MitM attack and delete the SSH2_MSG_EXT_INFO message sent before authentication starts, allowing the attacker to disable a subset of the keystroke timing obfuscation features introduced in OpenSSH 9.5.

The vulnerability was dubbed "Terrapin attack" and it affects both client and server implementations.

Mitigation

Update openssh package to one of the following versions: 1:8.4p1-5+deb11u3, 1:9.2p1-2+deb12u2.

Vulnerable software versions

Debian Linux: All versions

openssh (Debian package): before 1:9.2p1-2+deb12u2

External links

http://www.debian.org/security/2023/dsa-5586

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.

4) Inadequate Encryption Strength

EUVDB-ID: #VU84792

Risk: Low

CVSSv3.1: 3.2 [CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N/E:U/RL:O/RC:C]

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 openssh package to one of the following versions: 1:8.4p1-5+deb11u3, 1:9.2p1-2+deb12u2.

Vulnerable software versions

Debian Linux: All versions

openssh (Debian package): before 1:9.2p1-2+deb12u2

External links

http://www.debian.org/security/2023/dsa-5586

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.

5) OS Command Injection

EUVDB-ID: #VU84789

Risk: Medium

CVSSv3.1: 6.7 [CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H/E:P/RL:O/RC:C]

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 openssh package to one of the following versions: 1:8.4p1-5+deb11u3, 1:9.2p1-2+deb12u2.

Vulnerable software versions

Debian Linux: All versions

openssh (Debian package): before 1:9.2p1-2+deb12u2

External links

http://www.debian.org/security/2023/dsa-5586

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.