Multiple vulnerabilities in OpenSSH

1) OS Command Injection

EUVDB-ID: #VU84538

Risk: Medium

CVSSv3.1: 6.5 [CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2023-6004

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

Exploit availability: No

Description

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

The vulnerability exists due to improper input validation in OpenSSH client. If an invalid user or hostname that contained shell metacharacters was passed to ssh(1), and a ProxyCommand, LocalCommand directive or "match exec" predicate referenced the user or hostname via %u, %h or similar expansion token, then an attacker who could supply arbitrary user/hostnames to ssh(1) could potentially perform command injection depending on what quoting was present in the user-supplied ssh_config(5) directive.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

OpenSSH: 5.0p1 - 9.5p1

External links

http://www.openssh.com/releasenotes.html#9.6p1

Q & A

Can this vulnerability be exploited remotely?

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

2) 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

Install updates from vendor's website.

Vulnerable software versions

OpenSSH: 5.0p1 - 9.5p1

External links

http://www.openssh.com/openbsd.html
http://github.com/openssh/openssh-portable/commits/master
http://www.openssh.com/txt/release-9.6
http://www.terrapin-attack.com

Q & A

Can this vulnerability be exploited remotely?

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

3) 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

Install updates from vendor's website.

Vulnerable software versions

OpenSSH: 9.0p1 - 9.5p1

External links

http://www.openssh.com/txt/release-9.6
http://www.openwall.com/lists/oss-security/2023/12/18/2
http://github.com/openssh/openssh-portable/commit/7ef3787c84b6b524501211b11a26c742f829af1a
http://www.debian.org/security/2023/dsa-5586
http://vin01.github.io/piptagole/ssh/security/openssh/libssh/remote-code-execution/2023/12/20/openssh-proxycommand-libssh-rce.html
http://lists.debian.org/debian-lts-announce/2023/12/msg00017.html
http://www.openwall.com/lists/oss-security/2023/12/26/4

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker 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. However, proof of concept for this vulnerability is available.

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

Install updates from vendor's website.

Vulnerable software versions

OpenSSH: 9.0p1 - 9.5p1

External links

http://www.openssh.com/txt/release-9.6
http://www.openwall.com/lists/oss-security/2023/12/18/2
http://github.com/openssh/openssh-portable/commit/881d9c6af9da4257c69c327c4e2f1508b2fa754b
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.

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.