FreeBSD 8.3/9.0/9.1 NFS Server sys/kern/vfs_export.c vfs_hang_addrlist access control

CVSS Meta Temp Score
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CTI Interest Score
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5.9$0-$5k0.00

Summaryinfo

A vulnerability marked as critical has been reported in FreeBSD 8.3/9.0/9.1. Affected is the function vfs_hang_addrlist of the file sys/kern/vfs_export.c of the component NFS Server. This manipulation causes access control. This vulnerability is handled as CVE-2013-4851. Additionally, an exploit exists. To fix this issue, it is recommended to deploy a patch.

Detailsinfo

A vulnerability classified as critical was found in FreeBSD 8.3/9.0/9.1 (Operating System). Affected by this vulnerability is the function vfs_hang_addrlist of the file sys/kern/vfs_export.c of the component NFS Server. The manipulation with an unknown input leads to a access control vulnerability. The CWE definition for the vulnerability is CWE-264. As an impact it is known to affect confidentiality, and integrity. The summary by CVE is:

The vfs_hang_addrlist function in sys/kern/vfs_export.c in the NFS server implementation in the kernel in FreeBSD 8.3 and 9.x through 9.1-RELEASE-p5 controls authorization for host/subnet export entries on the basis of group information sent by the client, which allows remote attackers to bypass file permissions on NFS filesystems via crafted requests.

The weakness was released 07/26/2013 by Rick Macklem, Christopher Key and Tim Zingelman as FreeBSD-SA-13:08.nfsserver as confirmed advisory (Website). It is possible to read the advisory at freebsd.org. The public release was coordinated with the project team. This vulnerability is known as CVE-2013-4851 since 07/16/2013. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Technical details and also a public exploit are known. The attack technique deployed by this issue is T1068 according to MITRE ATT&CK. The advisory points out:

Systems that do provide the NFS service are only vulnerable when -mapall or -maproot is used in combination with network and/or host restrictions.

After immediately, there has been an exploit disclosed. It is declared as proof-of-concept. We expect the 0-day to have been worth approximately $5k-$25k. The vulnerability scanner Nessus provides a plugin with the ID 69483 (Debian DSA-2743-1 : kfreebsd-9 - privilege escalation/information leak), which helps to determine the existence of the flaw in a target environment. It is assigned to the family Debian Local Security Checks.

Upgrading to version 9.2-BETA2 eliminates this vulnerability. Applying the patch nfsserver.patch is able to eliminate this problem. The bugfix is ready for download at freebsd.org. The best possible mitigation is suggested to be patching the affected component. A possible mitigation has been published even before and not after the disclosure of the vulnerability.

The vulnerability is also documented in the databases at Tenable (69483), SecurityFocus (BID 61484†), OSVDB (95820†), Secunia (SA54280†) and Vulnerability Center (SBV-40743†). Entries connected to this vulnerability are available at VDB-10057, VDB-10058 and VDB-100035. Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Productinfo

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Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 6.5
VulDB Meta Temp Score: 5.9

VulDB Base Score: 6.5
VulDB Temp Score: 5.9
VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
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VulDB Base Score: 🔍
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Exploitinginfo

Class: Access control
CWE: CWE-264
CAPEC: 🔍
ATT&CK: 🔍

Physical: No
Local: No
Remote: Yes

Availability: 🔍
Access: Public
Status: Proof-of-Concept

EPSS Score: 🔍
EPSS Percentile: 🔍

Price Prediction: 🔍
Current Price Estimation: 🔍

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Nessus ID: 69483
Nessus Name: Debian DSA-2743-1 : kfreebsd-9 - privilege escalation/information leak
Nessus File: 🔍
Nessus Risk: 🔍
Nessus Family: 🔍

OpenVAS ID: 892743
OpenVAS Name: Debian Security Advisory DSA 2743-1 (kfreebsd-9 - privilege escalation/information leak
OpenVAS File: 🔍
OpenVAS Family: 🔍

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Patch
Status: 🔍

0-Day Time: 🔍
Exploit Delay Time: 🔍

Upgrade: FreeBSD 9.2-BETA2
Patch: nfsserver.patch

Timelineinfo

12/14/2012 🔍
07/16/2013 +214 days 🔍
07/26/2013 +10 days 🔍
07/26/2013 +0 days 🔍
07/26/2013 +0 days 🔍
07/29/2013 +3 days 🔍
07/29/2013 +0 days 🔍
07/29/2013 +0 days 🔍
07/30/2013 +1 days 🔍
08/02/2013 +3 days 🔍
05/21/2021 +2849 days 🔍

Sourcesinfo

Product: freebsd.org

Advisory: FreeBSD-SA-13:08.nfsserver
Researcher: Rick Macklem, Christopher Key, Tim Zingelman
Status: Confirmed
Confirmation: 🔍
Coordinated: 🔍

CVE: CVE-2013-4851 (🔍)
GCVE (CVE): GCVE-0-2013-4851
GCVE (VulDB): GCVE-100-9811

OVAL: 🔍

SecurityFocus: 61484 - FreeBSD 'nfsserver' Module CVE-2013-4851 Access Bypass Vulnerability
Secunia: 54280 - FreeBSD NFS Server Credential Validation Security Issue, Less Critical
OSVDB: 95820
Vulnerability Center: 40743 - FreeBSD 8.3, 9.0 - 9.1-RELEASE-p5 Remote NFS Security Bypass via vfs_hang_addrlist Function, Medium

scip Labs: https://www.scip.ch/en/?labs.20161013
See also: 🔍

Entryinfo

Created: 08/02/2013 10:29
Updated: 05/21/2021 07:23
Changes: 08/02/2013 10:29 (85), 05/06/2017 20:04 (4), 05/21/2021 07:23 (3)
Complete: 🔍
Committer: olku
Cache ID: 216:A19:103

Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

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