Vulnerability identifier: #VU17350

Vulnerability risk: Low

CVSSv3.1: 6.5 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2018-20217

CWE-ID: CWE-617

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Kerberos 5
Client/Desktop applications / Software for system administration

Vendor: MIT

Description

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to a reachable assertion in in the KDC. A remote attacker can obtain a krbtgt ticket using an older encryption type (single-DES, triple-DES, or RC4) and crash the KDC by making an S4U2Self request.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Kerberos 5: 1.14 - 1.16.3

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External links
http://krbdev.mit.edu/rt/Ticket/Display.html?id=8763
http://github.com/krb5/krb5/commit/5e6d1796106df8ba6bc1973ee0917c170d929086

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.