Heimdal CVE-2017-11103 Man in the Middle Security Bypass Vulnerability
by CIRT Team
Description: Heimdal before 7.4 allows remote attackers to impersonate services with Orpheus’ Lyre attacks because it obtains service-principal names in a way that violates the Kerberos 5 protocol specification. In _krb5_extract_ticket() the KDC-REP service name must be obtained from the encrypted version stored in ‘enc_part’ instead of the unencrypted version stored in ‘ticket’. Use of the unencrypted version provides an opportunity for successful server impersonation and other attacks. NOTE: this CVE is only for Heimdal and other products that embed Heimdal code; it does not apply to other instances in which this part of the Kerberos 5 protocol specification is violated.
Impact: Successfully exploiting this issue may allow attackers to bypass certain security restrictions and perform unauthorized actions by conducting a man-in-the-middle attack. This may lead to other attacks.
Mitigation: Updates are available. Please check specific vendor advisory for more information.
Reference URL’s:
- https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2017-11103
- http://www.securityfocus.com/bid/99551/info
- https://www.freebsd.org/security/advisories/FreeBSD-SA-17%3A05.heimdal.asc
- https://www.samba.org/samba/security/CVE-2017-11103.html
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