Short Name |
APP:KERBEROS:CVE-2017-17439DOS |
---|---|
Severity |
Major |
Recommended |
Yes |
Recommended Action |
Drop |
Category |
APP |
Keywords |
Heimdal KDC ASN1 DER Length Denial of Service |
Release Date |
2018/02/27 |
Update Number |
3048 |
Supported Platforms |
idp-4.0+, isg-3.0+, j-series-9.5+, mx-11.4+, srx-12.1+, srx-branch-12.1+, vmx-17.4+, vsrx-12.1+, vsrx3bsd-18.2+ |
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.
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.