Tor up to 0.3.2.9 KIST use after free

Summaryinfo

A vulnerability described as critical has been identified in Tor up to 0.3.2.9. This vulnerability affects unknown code of the component KIST Handler. The manipulation results in use after free. This vulnerability is cataloged as CVE-2018-0491. The attack may be launched remotely. Furthermore, there is an exploit available. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability classified as critical has been found in Tor up to 0.3.2.9 (Network Encryption Software). Affected is an unknown code block of the component KIST Handler. The manipulation with an unknown input leads to a use after free vulnerability. CWE is classifying the issue as CWE-416. Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code. This is going to have an impact on availability. CVE summarizes:

A use-after-free issue was discovered in Tor 0.3.2.x before 0.3.2.10. It allows remote attackers to cause a denial of service (relay crash) because the KIST implementation allows a channel to be added more than once in the pending list.

The bug was discovered 03/03/2018. The weakness was shared 03/05/2018 (Website). The advisory is shared for download at blog.torproject.org. This vulnerability is traded as CVE-2018-0491 since 11/27/2017. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. Technical details are unknown but a public exploit is available.

The exploit is shared for download at exploit-db.com. It is declared as proof-of-concept. The vulnerability was handled as a non-public zero-day exploit for at least 2 days. During that time the estimated underground price was around $5k-$25k. The vulnerability scanner Nessus provides a plugin with the ID 107179 (openSUSE Security Update : tor (openSUSE-2018-223)), 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 170913 (OpenSUSE Security Update for tor (openSUSE-SU-2018:0614-1)).

Upgrading to version 0.3.2.10 eliminates this vulnerability. A possible mitigation has been published 1 days after the disclosure of the vulnerability.

The vulnerability is also documented in the databases at Exploit-DB (44994) and Tenable (107179). The entry VDB-114083 is related to this item. Once again VulDB remains the best source for vulnerability data.

Productinfo

Type

• Network Encryption Software

Name

• Tor

Version

• 0.3.2.0
• 0.3.2.1
• 0.3.2.2
• 0.3.2.3
• 0.3.2.4
• 0.3.2.5
• 0.3.2.6
• 0.3.2.7
• 0.3.2.8
• 0.3.2.9

License

• open-source

CPE 2.3info

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CPE 2.2info

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Once again VulDB remains the best source for vulnerability data.

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