CVE-2024-56089: Technitium DNS Cache Poisoning Vulnerability

CVE-2024-56089 Overview

CVE-2024-56089 is a high-severity DNS cache poisoning vulnerability affecting Technitium DNS Server through version v13.2.2. This vulnerability enables attackers to conduct DNS cache poisoning attacks by reviving the birthday attack technique, allowing malicious actors to inject fake DNS responses into the server's cache.

DNS cache poisoning attacks represent a significant threat to network infrastructure as they can redirect legitimate traffic to attacker-controlled servers, enabling phishing campaigns, malware distribution, and man-in-the-middle attacks. The birthday attack revival method exploits weaknesses in random number generation (CWE-330) used in DNS transaction IDs.

Critical Impact
Attackers can inject malicious DNS records into the cache, potentially redirecting users to fraudulent websites without any user interaction required.

Affected Products

Technitium DNS Server versions through v13.2.2

Discovery Timeline

2025-12-01 - CVE-2024-56089 published to NVD
2025-12-01 - Last updated in NVD database

Technical Details for CVE-2024-56089

Vulnerability Analysis

This vulnerability is classified under CWE-330 (Use of Insufficiently Random Values) and carries a CVSS v3.1 score of 7.5 (High) with the vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N.

The CVSS breakdown indicates:

Attack Vector (AV:N): Network-based exploitation
Attack Complexity (AC:L): Low complexity to execute
Privileges Required (PR:N): No privileges needed
User Interaction (UI:N): No user interaction required
Scope (S:U): Unchanged scope
Integrity Impact (I:H): High integrity impact through cache manipulation

The Exploit Prediction Scoring System (EPSS) rates this vulnerability with a probability of 0.038%, placing it at the 11th percentile as of 2025-12-16.

Root Cause

The root cause of this vulnerability lies in the insufficient randomness of DNS transaction identifiers and potentially source port selection in Technitium DNS Server. The birthday attack exploits the probability mathematics behind collision detection - when insufficient entropy exists in these values, an attacker can feasibly guess valid combinations to inject fraudulent responses.

The birthday attack methodology significantly reduces the computational effort required to successfully poison DNS caches by exploiting the birthday paradox, where the probability of collisions increases faster than linearly with the number of attempts.

Attack Vector

The attack follows a network-based exploitation path:

Target Identification: The attacker identifies a Technitium DNS Server running a vulnerable version
Query Triggering: The attacker causes the target DNS server to make recursive queries for a domain the attacker controls or wishes to poison
Race Condition Exploitation: While the legitimate query is pending, the attacker floods the target server with forged DNS responses containing:
- Guessed transaction IDs
- Spoofed source IP (appearing to come from authoritative nameservers)
- Malicious DNS records pointing to attacker-controlled infrastructure
Cache Poisoning Success: If a forged response arrives with a matching transaction ID before the legitimate response, the malicious record is cached

The attack does not require authentication and can be executed remotely over the network. Due to the insufficient randomness in transaction ID generation, the birthday attack methodology makes successful guessing feasible within practical timeframes.

Detection Methods for CVE-2024-56089

Indicators of Compromise

Unusual DNS response patterns with unexpected IP addresses for known domains
High volume of DNS queries from the same source targeting the DNS server
DNS records pointing to suspicious or recently registered domains
Unexpected changes in cached DNS records
Multiple DNS responses for single queries (race condition indicator)

Detection Strategies

Organizations should implement the following detection mechanisms:

DNS Query/Response Monitoring: Monitor for anomalous patterns in DNS traffic, particularly multiple responses to single queries or responses from unexpected sources
Cache Integrity Verification: Periodically verify cached DNS records against authoritative sources to detect poisoned entries
Network Traffic Analysis: Analyze network traffic for signs of DNS response flooding, which is characteristic of cache poisoning attempts
DNSSEC Validation Monitoring: If DNSSEC is implemented, monitor for validation failures which may indicate poisoning attempts

Monitoring Recommendations

Deploy comprehensive DNS monitoring that includes:

Real-time alerting on DNS cache changes for critical domains
Network-level detection of DNS amplification or flooding patterns
Log aggregation from DNS servers with analysis for anomalous resolution patterns
Baseline establishment for normal DNS query volumes and response times

How to Mitigate CVE-2024-56089

Immediate Actions Required

Upgrade Technitium DNS Server to version v13.4 or later which contains the security fix
Enable DNSSEC validation to cryptographically verify DNS responses
Review and audit current DNS cache contents for potentially poisoned entries
Implement source port randomization if not already enabled
Consider deploying DNS-over-HTTPS (DoH) or DNS-over-TLS (DoT) for upstream queries

Patch Information

Technitium has addressed this vulnerability in version v13.4 as documented in their changelog. Organizations running affected versions should upgrade immediately.

For patch information and download links, refer to:

Workarounds

If immediate patching is not possible, implement the following compensating controls:

Enable DNSSEC: Configure DNSSEC validation to reject unsigned or improperly signed DNS responses
Restrict Recursion: Limit recursive DNS queries to trusted internal networks only
Implement Rate Limiting: Configure rate limiting on DNS queries to reduce the effectiveness of flooding attacks
Network Segmentation: Isolate DNS servers and restrict access to authorized systems only
Deploy Additional Monitoring: Enhance monitoring capabilities to detect cache poisoning attempts in real-time