CVE-2017-17439 : Exploit Details and Defense Strategies

In December 2017, CVE-2017-17439 was published, highlighting a vulnerability in Heimdal version 7.4 that could lead to a remote crash due to crafted UDP packets. Attackers could exploit this flaw by including empty data fields for client name or realm, causing a segmentation fault. This vulnerability specifically affects the _kdc_as_rep function in kdc/kerberos5.c and the der_length_visible_string function in lib/asn1/der_length.c.

Understanding CVE-2017-17439

This section provides insights into the nature and impact of the CVE-2017-17439 vulnerability.

What is CVE-2017-17439?

CVE-2017-17439 is a vulnerability in Heimdal version 7.4 that allows remote attackers to crash the Key Distribution Center (KDC) by sending manipulated UDP packets with empty data fields, triggering a segmentation fault.

The Impact of CVE-2017-17439

The vulnerability in Heimdal version 7.4 could be exploited by attackers to remotely crash the KDC, potentially leading to service disruption and system instability.

Technical Details of CVE-2017-17439

Explore the technical aspects of the CVE-2017-17439 vulnerability.

Vulnerability Description

The vulnerability in Heimdal version 7.4 arises from the mishandling of crafted UDP packets containing empty data fields, leading to NULL pointer dereference and a segmentation fault.

Affected Systems and Versions

Product: Not applicable
Vendor: Not applicable
Versions: All versions up to and including 7.4

Exploitation Mechanism

Attackers can exploit CVE-2017-17439 by sending specially crafted UDP packets with empty data fields for client name or realm, causing the parser to access NULL pointers erroneously.

Mitigation and Prevention

Learn how to mitigate the risks associated with CVE-2017-17439.

Immediate Steps to Take

Apply patches or updates provided by Heimdal to address the vulnerability.
Implement network segmentation to limit exposure to potential attacks.
Monitor network traffic for any suspicious activity that may indicate exploitation attempts.

Long-Term Security Practices

Regularly update Heimdal software to the latest version to prevent known vulnerabilities.
Conduct security assessments and penetration testing to identify and address potential weaknesses.

Patching and Updates

Heimdal users should promptly apply patches and updates released by the vendor to mitigate the CVE-2017-17439 vulnerability.