APP: Heimdal KDC ASN1 DER Length Denial of Service
This signature detects attempts to exploit a known vulnerability against Heimdal, a Kerberos implementation. A successful attack can result in a denial-of-service condition.
Extended Description
In Heimdal through 7.4, remote unauthenticated attackers are able to crash the KDC by sending a crafted UDP packet containing empty data fields for client name or realm. The parser would unconditionally dereference NULL pointers in that case, leading to a segmentation fault. This is related to the _kdc_as_rep function in kdc/kerberos5.c and the der_length_visible_string function in lib/asn1/der_length.c.
Affected Products
Heimdal_project heimdal
References
CVE: CVE-2017-17439
Short Name
APP:KERBEROS:CVE-2017-17439DOS
Severity
Major
Recommended
True
Recommended Action
Drop
Category
APP
Keywords
ASN1 CVE-2017-17439 DER Denial Heimdal KDC Length Service of
Release Date
02/27/2018
Supported Platforms
srx-branch-12.3
srx-19.3
srx-branch-19.3
vsrx3bsd-19.2
srx-branch-19.4
vsrx-19.4
mx-12.3
mx-19.4
vmx-19.4
mx-19.3
vsrx3bsd-19.4
srx-19.4
vsrx-12.3
vmx-19.3
vsrx-19.2
srx-12.3
Sigpack Version
3590
Port
UDP/88
False Positive
Unknown
Vendors
Debian
Heimdal_project
CVSS Score
5.0