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RHEL 7 : libssh (Unpatched Vulnerability)

medium Nessus Plugin ID 195761

Synopsis

The remote Red Hat 7 host is affected by multiple vulnerabilities that will not be patched.

Description

The remote Redhat Enterprise Linux 7 host has one or more packages installed that are affected by multiple vulnerabilities that have been acknowledged by the vendor but will not be patched.

 - libssh: NULL pointer dereference in sftpserver.c if ssh_buffer_new returns NULL (CVE-2020-16135)

 - libssh: authorization bypass in pki_verify_data_signature (CVE-2023-2283)

 - A flaw has been found in libssh in versions prior to 0.9.6. The SSH protocol keeps track of two shared secrets during the lifetime of the session. One of them is called secret_hash and the other session_id.
 Initially, both of them are the same, but after key re-exchange, previous session_id is kept and used as an input to new secret_hash. Historically, both of these buffers had shared length variable, which worked as long as these buffers were same. But the key re-exchange operation can also change the key exchange method, which can be based on hash of different size, eventually creating secret_hash of different size than the session_id has. This becomes an issue when the session_id memory is zeroed or when it is used again during second key re-exchange. (CVE-2021-3634)

 - A NULL pointer dereference was found In libssh during re-keying with algorithm guessing. This issue may allow an authenticated client to cause a denial of service. (CVE-2023-1667)

 - A flaw was found in libssh. By utilizing the ProxyCommand or ProxyJump feature, users can exploit unchecked hostname syntax on the client. This issue may allow an attacker to inject malicious code into the command of the features mentioned through the hostname parameter. (CVE-2023-6004)

 - A flaw was found in the libssh implements abstract layer for message digest (MD) operations implemented by different supported crypto backends. The return values from these were not properly checked, which could cause low-memory situations failures, NULL dereferences, crashes, or usage of the uninitialized memory as an input for the KDF. In this case, non-matching keys will result in decryption/integrity failures, terminating the connection. (CVE-2023-6918)

Note that Nessus has not tested for these issues but has instead relied on the package manager's report that the package is installed.

Solution

The vendor has acknowledged the vulnerabilities but no solution has been provided. Refer to the vendor for remediation guidance.

Plugin Details

Severity: Medium

ID: 195761

File Name: redhat_unpatched-libssh-rhel7.nasl

Version: 1.0

Type: local

Agent: unix

Published: 5/11/2024

Updated: 5/11/2024

Supported Sensors: Frictionless Assessment AWS, Frictionless Assessment Azure, Frictionless Assessment Agent, Nessus Agent, Agentless Assessment, Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 4.9

CVSS v2

Risk Factor: Medium

Base Score: 4.3

Temporal Score: 3.4

Vector: CVSS2#AV:N/AC:M/Au:N/C:N/I:N/A:P

CVSS Score Source: CVE-2020-16135

CVSS v3

Risk Factor: Medium

Base Score: 6.5

Temporal Score: 5.9

Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

Temporal Vector: CVSS:3.0/E:P/RL:O/RC:C

CVSS Score Source: CVE-2023-2283

Vulnerability Information

CPE: cpe:/o:redhat:enterprise_linux:6, cpe:/o:redhat:enterprise_linux:7, cpe:/o:redhat:enterprise_linux:8, p-cpe:/a:redhat:enterprise_linux:libssh, p-cpe:/a:redhat:enterprise_linux:libssh2

Required KB Items: Host/local_checks_enabled, Host/RedHat/release, Host/RedHat/rpm-list, Host/cpu

Exploit Available: true

Exploit Ease: Exploits are available

Vulnerability Publication Date: 7/29/2020

Reference Information

CVE: CVE-2020-16135, CVE-2021-3634, CVE-2023-1667, CVE-2023-2283, CVE-2023-6004, CVE-2023-6918