Secunia Research Advisory

FreeBSD NFS Multiple Denial of Service Vulnerabilities


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                     Secunia Research 2018/11/30

        FreeBSD NFS Multiple Denial of Service Vulnerabilities
							  
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Table of Contents
 
Affected Software....................................................1
Severity.............................................................2
Description of Vulnerabilities.......................................3
Solution.............................................................4
Time Table...........................................................5
Credits..............................................................6
References...........................................................7
About Flexera .......................................................8
Verification.........................................................9

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1) Affected Software

* FreeBSD version 11.2.

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2) Severity

Rating: Less critical
Impact: Denial of Service
Where:  Local Area Network

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3) Description of Vulnerabilities

Secunia Research has discovered multiple vulnerabilities in FreeBSD,
which can be exploited by malicious people to cause a DoS (Denial of
Service).

1) An integer overflow error in the "nfsm_advance()" function
(sys/fs/nfs/nfs_commonsubs.c) when handling client address length
field can be exploited to crash the system by sending a specially
crafted NFSv4 request.

2) An error in the "nfsrvd_readdirplus()" function
(sys/fs/nfsserver/nfs_nfsdport.c) can be exploited to exhaust
available memory resources by sending a specially crafted NFS request.

The vulnerabilities are confirmed in versions 11.2-RELEASE-p4 and 
12.0-ALPHA8 and reported in version 11.2.

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4) Solution

Update FreeBSD or apply a patch.
https://www.freebsd.org/security/advisories/FreeBSD-SA-18:13.nfs.asc
https://svnweb.freebsd.org/base?view=revision&revision=341088

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5) Time Table

2018/11/15 - FreeBSD team contacted with vulnerabilities details.
2018/11/17 - FreeBSD team confirmed the vulnerabilities.
2018/11/27 - Release of vendor patch.
2018/11/28 - Release of Secunia Advisory SA85555.
2018/11/30 - Public disclosure of Secunia Research Advisory.

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6) Credits
 
Jakub Jirasek, Secunia Research at Flexera.

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7) References

The FreeBSD CNA has assigned CVE-2018-17158 and CVE-2018-17159
identifiers for the vulnerabilities through the Common Vulnerabilities
and Exposures (CVE) project.

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8) About Flexera

Flexera helps application producers and enterprises increase
application usage and the value they derive from their software.

https://www.flexera.com

Flexera delivers market-leading Software Vulnerability Management
solutions enabling enterprises to proactively identify and
remediate software vulnerabilities, effectively reducing the risk of
costly security breaches.

Flexera supports and contributes to the community in several
ways. We have always believed that reliable vulnerability
intelligence and tools to aid identifying and fixing vulnerabilities
should be freely available for consumers to ensure that users,
who care about their online privacy and security, can stay secure.
Only a few vendors address vulnerabilities in a proper way and help
users get updated and stay secure. End-users (whether private
individuals or businesses) are otherwise left largely alone, and
that is why back in 2002, Secunia Research started investigating,
coordinating disclosure and verifying software vulnerabilities.
In 2016, Secunia Research became a part of Flexera and today
our in-house software vulnerability research remains the core of
the Software Vulnerability Management products at Flexera.

The public Secunia Advisory database contains information for
researchers, security enthusiasts, and consumers to lookup individual
products and vulnerabilities and assess, whether they need to take
any actions to secure their systems or whether a given vulnerability
has already been discovered.

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9) Verification

Please verify this advisory by visiting the Secunia Research website:
https://www.flexera.com/about-us/secunia-research/advisories/sr-2018-24.html

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