A vulnerability was found in Rack up to 2.0.5. It has been rated as problematic. Affected by this issue is an unknown functionality of the component Multipart Parser. The manipulation as part of a Request leads to a resource consumption vulnerability. Using CWE to declare the problem leads to 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. Impacted is availability. CVE summarizes:

There is a possible DoS vulnerability in the multipart parser in Rack before 2.0.6. Specially crafted requests can cause the multipart parser to enter a pathological state, causing the parser to use CPU resources disproportionate to the request size.

The bug was discovered 11/05/2018. The weakness was shared 11/13/2018 (Website). The advisory is shared for download at groups.google.com. This vulnerability is handled as CVE-2018-16470 since 09/04/2018. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. There are neither technical details nor an exploit publicly available. The MITRE ATT&CK project declares the attack technique as T1499.

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 120874 (Fedora 29 : 1:rubygem-rack (2018-e8ff8b7f8e)), which helps to determine the existence of the flaw in a target environment. It is assigned to the family Fedora Local Security Checks and running in the context l. The commercial vulnerability scanner Qualys is able to test this issue with plugin 172093 (OpenSUSE Security Update for rmt-server (openSUSE-SU-2019:0185-1)).

Upgrading to version 2.0.6 eliminates this vulnerability. A possible mitigation has been published 3 weeks after the disclosure of the vulnerability.

The vulnerability is also documented in the vulnerability database at Tenable (120874). The entry 126141 is related to this item.

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• Rack

Version

• 2.0.0
• 2.0.1
• 2.0.2
• 2.0.3
• 2.0.4
• 2.0.5

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