FreeBSD 8.3/9.0/9.1 NFS Server sys/kern/vfs_export.c vfs_hang_addrlist access control
CVSS Meta Temp Score | Current Exploit Price (≈) | CTI Interest Score |
---|---|---|
5.9 | $0-$5k | 0.00 |
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 vulnerability database at Tenable (69483). Entries connected to this vulnerability are available at 10057, 10058 and 100035.
Product
Type
Name
Version
License
CPE 2.3
CPE 2.2
CVSSv4
VulDB CVSS-B Score: 🔍VulDB CVSS-BT Score: 🔍
VulDB Vector: 🔍
VulDB Reliability: 🔍
CVSSv3
VulDB Meta Base Score: 6.5VulDB Meta Temp Score: 5.9
VulDB Base Score: 6.5
VulDB Temp Score: 5.9
VulDB Vector: 🔍
VulDB Reliability: 🔍
CVSSv2
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Vector | Complexity | Authentication | Confidentiality | Integrity | Availability |
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unlock | unlock | unlock | unlock | unlock | unlock |
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unlock | unlock | unlock | unlock | unlock | unlock |
VulDB Base Score: 🔍
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Exploiting
Class: Access controlCWE: CWE-264
ATT&CK: T1068
Local: No
Remote: Yes
Availability: 🔍
Access: Public
Status: Proof-of-Concept
EPSS Score: 🔍
EPSS Percentile: 🔍
Price Prediction: 🔍
Current Price Estimation: 🔍
0-Day | unlock | unlock | unlock | unlock |
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Today | unlock | unlock | unlock | unlock |
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 Intelligence
Interest: 🔍Active Actors: 🔍
Active APT Groups: 🔍
Countermeasures
Recommended: PatchStatus: 🔍
0-Day Time: 🔍
Exploit Delay Time: 🔍
Upgrade: FreeBSD 9.2-BETA2
Patch: nfsserver.patch
Timeline
12/14/2012 🔍07/16/2013 🔍
07/26/2013 🔍
07/26/2013 🔍
07/26/2013 🔍
07/29/2013 🔍
07/29/2013 🔍
07/29/2013 🔍
07/30/2013 🔍
08/02/2013 🔍
05/21/2021 🔍
Sources
Product: freebsd.orgAdvisory: FreeBSD-SA-13:08.nfsserver
Researcher: Rick Macklem, Christopher Key, Tim Zingelman
Status: Confirmed
Confirmation: 🔍
Coordinated: 🔍
CVE: CVE-2013-4851 (🔍)
OVAL: 🔍
Vulnerability Center: 40743 - FreeBSD 8.3, 9.0 - 9.1-RELEASE-p5 Remote NFS Security Bypass via vfs_hang_addrlist Function, Medium
SecurityFocus: 61484 - FreeBSD 'nfsserver' Module CVE-2013-4851 Access Bypass Vulnerability
Secunia: 54280 - FreeBSD NFS Server Credential Validation Security Issue, Less Critical
OSVDB: 95820
scip Labs: https://www.scip.ch/en/?labs.20161013
See also: 🔍
Entry
Created: 08/02/2013 10:29Updated: 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
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