Overview
CVE-2024-56089 details a vulnerability within Technitium DNS Server, specifically affecting versions up to and including v13.2.2. This security flaw enables attackers to perform DNS cache poisoning attacks by exploiting the ‘birthday attack’ method. Successfully exploiting this vulnerability allows attackers to inject fake DNS responses into the DNS server’s cache, potentially redirecting users to malicious websites or services.
Technical Details
The vulnerability stems from insufficient randomization in the DNS query ID generation process within the Technitium DNS Server. The birthday attack leverages the probability that, in a set of randomly chosen elements, a pair of elements will share the same value. In the context of DNS, an attacker attempts to guess the transaction ID of a DNS query. By sending a large number of spoofed DNS responses with different, but overlapping, transaction IDs, the probability of successfully injecting a malicious response into the cache increases significantly. Technitium DNS Server versions prior to the fix exhibited a predictable pattern in query ID generation, making them susceptible to this attack.
CVSS Analysis
Currently, the CVE entry lists the CVSS score as N/A and severity as N/A. This often indicates that the analysis is pending or incomplete. While an official score is unavailable, given the nature of the vulnerability (DNS cache poisoning), its impact could be significant depending on the deployment and reliance on the affected DNS server. A realistic estimated severity could be considered medium, as the attack requires some level of network proximity and is not remotely exploitable without additional factors.
Possible Impact
A successful DNS cache poisoning attack via CVE-2024-56089 can lead to several detrimental outcomes:
- Redirection to Malicious Websites: Users attempting to access legitimate websites could be redirected to attacker-controlled websites designed to steal credentials, distribute malware, or conduct phishing attacks.
- Man-in-the-Middle Attacks: Attackers can intercept and manipulate network traffic between users and legitimate servers.
- Service Disruption: Poisoned DNS entries can prevent users from accessing critical services.
Mitigation or Patch Steps
The recommended mitigation is to upgrade to Technitium DNS Server version 13.4 or later. This version includes improved DNS query ID randomization, effectively preventing the birthday attack. You can download the latest version from the official Technitium website.
Additionally, consider implementing other DNS security best practices, such as:
- Regularly monitoring DNS server logs for suspicious activity.
- Limiting DNS query recursion to trusted sources.
- Considering deployment of DNSSEC (DNS Security Extensions) for enhanced DNS authentication, although this requires support from the domain and resolvers involved.
