CVE-2023-50868

The Closest Encloser Proof aspect of the DNS protocol (in RFC 5155 when RFC 9276 guidance is skipped) allows remote attackers to cause a denial of service (CPU consumption for SHA-1 computations) via DNSSEC responses in a random subdomain attack, aka the NSEC3 issue. The RFC 5155 specification implies that an algorithm must perform thousands of iterations of a hash function in certain situations.

Weakness

The product does not properly control the allocation and maintenance of a limited resource.

Affected Software

Potential Mitigations

• Mitigation of resource exhaustion attacks requires that the target system either:

• The first of these solutions is an issue in itself though, since it may allow attackers to prevent the use of the system by a particular valid user. If the attacker impersonates the valid user, they may be able to prevent the user from accessing the server in question.

• The second solution is simply difficult to effectively institute – and even when properly done, it does not provide a full solution. It simply makes the attack require more resources on the part of the attacker.

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/147.html
• https://cwe.mitre.org/data/definitions/227.html
• https://cwe.mitre.org/data/definitions/492.html

References

• http://www.openwall.com/lists/oss-security/2024/02/16/2
• http://www.openwall.com/lists/oss-security/2024/02/16/3
• https://access.redhat.com/security/cve/CVE-2023-50868
• https://bugzilla.suse.com/show_bug.cgi?id=1219826
• https://datatracker.ietf.org/doc/html/rfc5155
• https://docs.powerdns.com/recursor/security-advisories/powerdns-advisory-2024-01.html
• https://gitlab.nic.cz/knot/knot-resolver/-/releases/v5.7.1
• https://kb.isc.org/docs/cve-2023-50868
• https://lists.debian.org/debian-lts-announce/2024/02/msg00006.html
• https://lists.debian.org/debian-lts-announce/2024/05/msg00011.html
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/6FV5O347JTX7P5OZA6NGO4MKTXRXMKOZ/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/BUIP7T7Z4T3UHLXFWG6XIVDP4GYPD3AI/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/HVRDSJVZKMCXKKPP6PNR62T7RWZ3YSDZ/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/IGSLGKUAQTW5JPPZCMF5YPEYALLRUZZ6/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/PNNHZSZPG2E7NBMBNYPGHCFI4V4XRWNQ/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/RGS7JN6FZXUSTC2XKQHH27574XOULYYJ/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/SVYA42BLXUCIDLD35YIJPJSHDIADNYMP/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/TEXGOYGW7DBS3N2QSSQONZ4ENIRQEAPG/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/UQESRWMJCF4JEYJEAKLRM6CT55GLJAB7/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ZDZFMEKQTZ4L7RY46FCENWFB5MDT263R/
• https://lists.thekelleys.org.uk/pipermail/dnsmasq-discuss/2024q1/017430.html
• https://nlnetlabs.nl/news/2024/Feb/13/unbound-1.19.1-released/
• https://security.netapp.com/advisory/ntap-20240307-0008/
• https://www.isc.org/blogs/2024-bind-security-release/
• http://www.openwall.com/lists/oss-security/2024/02/16/2
• http://www.openwall.com/lists/oss-security/2024/02/16/3
• https://access.redhat.com/security/cve/CVE-2023-50868
• https://bugzilla.suse.com/show_bug.cgi?id=1219826
• https://datatracker.ietf.org/doc/html/rfc5155
• https://docs.powerdns.com/recursor/security-advisories/powerdns-advisory-2024-01.html
• https://gitlab.nic.cz/knot/knot-resolver/-/releases/v5.7.1
• https://kb.isc.org/docs/cve-2023-50868
• https://lists.debian.org/debian-lts-announce/2024/02/msg00006.html
• https://lists.debian.org/debian-lts-announce/2024/05/msg00011.html
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/6FV5O347JTX7P5OZA6NGO4MKTXRXMKOZ/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/BUIP7T7Z4T3UHLXFWG6XIVDP4GYPD3AI/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/HVRDSJVZKMCXKKPP6PNR62T7RWZ3YSDZ/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/IGSLGKUAQTW5JPPZCMF5YPEYALLRUZZ6/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/PNNHZSZPG2E7NBMBNYPGHCFI4V4XRWNQ/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/RGS7JN6FZXUSTC2XKQHH27574XOULYYJ/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/SVYA42BLXUCIDLD35YIJPJSHDIADNYMP/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/TEXGOYGW7DBS3N2QSSQONZ4ENIRQEAPG/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/UQESRWMJCF4JEYJEAKLRM6CT55GLJAB7/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ZDZFMEKQTZ4L7RY46FCENWFB5MDT263R/
• https://lists.thekelleys.org.uk/pipermail/dnsmasq-discuss/2024q1/017430.html
• https://nlnetlabs.nl/news/2024/Feb/13/unbound-1.19.1-released/
• https://security.netapp.com/advisory/ntap-20240307-0008/
• https://www.isc.org/blogs/2024-bind-security-release/