FreeBSD : FreeBSD -- Incorrect error handling in PAM policy parser (6e8f9003-6007-11e6-a6c3-14dae9d210b8)

critical Nessus Plugin ID 92903

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Synopsis

The remote FreeBSD host is missing one or more security-related updates.

Description

The OpenPAM library searches for policy definitions in several locations. While doing so, the absence of a policy file is a soft failure (handled by searching in the next location) while the presence of an invalid file is a hard failure (handled by returning an error to the caller).

The policy parser returns the same error code (ENOENT) when a syntactically valid policy references a non-existent module as when the requested policy file does not exist. The search loop regards this as a soft failure and looks for the next similarly-named policy, without discarding the partially-loaded configuration.

A similar issue can arise if a policy contains an include directive that refers to a non-existent policy. Impact : If a module is removed, or the name of a module is misspelled in the policy file, the PAM library will proceed with a partially loaded configuration. Depending on the exact circumstances, this may result in a fail-open scenario where users are allowed to log in without a password, or with an incorrect password.

In particular, if a policy references a module installed by a package or port, and that package or port is being reinstalled or upgraded, there is a brief window of time during which the module is absent and policies that use it may fail open. This can be especially damaging to Internet-facing SSH servers, which are regularly subjected to brute-force scans.

Solution

Update the affected packages.

Plugin Details

Severity: Critical

ID: 92903

File Name: freebsd_pkg_6e8f9003600711e6a6c314dae9d210b8.nasl

Version: 2.5

Type: local

Family: FreeBSD Local Security Checks

Published: 8/12/2016

Updated: 1/4/2021

Configuration: Enable paranoid mode

Supported Sensors: Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 6.7

CVSS v2

Risk Factor: High

Base Score: 7.5

Temporal Score: 5.5

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

CVSS v3

Risk Factor: Critical

Base Score: 9.8

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

Vulnerability Information

CPE: p-cpe:/a:freebsd:freebsd:freebsd, cpe:/o:freebsd:freebsd

Required KB Items: Host/local_checks_enabled, Settings/ParanoidReport, Host/FreeBSD/release, Host/FreeBSD/pkg_info

Exploit Ease: No known exploits are available

Patch Publication Date: 8/11/2016

Vulnerability Publication Date: 6/3/2014

Reference Information

CVE: CVE-2014-3879

BID: 67808

FreeBSD: SA-14:13.pam

Detections

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