libtirpc up to 1.0.2-rc1 File Descriptors resource consumption

Summaryinfo

A vulnerability was found in libtirpc up to 1.0.2-rc1. It has been classified as problematic. The affected element is an unknown function of the component File Descriptors. This manipulation causes resource consumption. This vulnerability is registered as CVE-2018-14621. Remote exploitation of the attack is possible. No exploit is available. It is recommended to apply a patch to fix this issue.

Detailsinfo

A vulnerability was found in libtirpc up to 1.0.2-rc1. It has been declared as problematic. Affected by this vulnerability is an unknown code block of the component File Descriptors. The manipulation with an unknown input leads to a resource consumption vulnerability. The CWE definition for the vulnerability is CWE-400. The product does not properly control the allocation and maintenance of a limited resource, thereby enabling an actor to influence the amount of resources consumed, eventually leading to the exhaustion of available resources. As an impact it is known to affect availability. The summary by CVE is:

An infinite loop vulnerability was found in libtirpc before version 1.0.2-rc2. With the port to using poll rather than select, exhaustion of file descriptors would cause the server to enter an infinite loop, consuming a large amount of CPU time and denying service to other clients until restarted.

The bug was discovered 08/22/2018. The weakness was published 08/30/2018 as confirmed git commit (GIT Repository). It is possible to read the advisory at git.linux-nfs.org. This vulnerability is known as CVE-2018-14621 since 07/27/2018. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. The technical details are unknown and an exploit is not publicly available. The attack technique deployed by this issue is T1499 according to MITRE ATT&CK.

The vulnerability was handled as a non-public zero-day exploit for at least 8 days. During that time the estimated underground price was around $0-$5k. The vulnerability scanner Nessus provides a plugin with the ID 118141 (SUSE SLES11 Security Update : libtirpc (SUSE-SU-2018:3146-1)), which helps to determine the existence of the flaw in a target environment. It is assigned to the family SuSE Local Security Checks and running in the context l. The commercial vulnerability scanner Qualys is able to test this issue with plugin 171637 (SUSE Enterprise Linux Security Update for libtirpc (SUSE-SU-2018:3146-1)).

Upgrading to version 1.0.2-rc2 eliminates this vulnerability. Applying a patch is able to eliminate this problem. The bugfix is ready for download at git.linux-nfs.org. The best possible mitigation is suggested to be patching the affected component. A possible mitigation has been published 2 months after the disclosure of the vulnerability.

The vulnerability is also documented in the vulnerability database at Tenable (118141). Similar entry is available at VDB-123416. Be aware that VulDB is the high quality source for vulnerability data.

Productinfo

Name

• libtirpc

Version

• 1.0.2-rc1

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