CVE-2006-2017 in Dnsmasq
Summary
by MITRE
Dnsmasq 2.29 allows remote attackers to cause a denial of service (application crash) via a DHCP client broadcast reply request.
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Analysis
by VulDB Data Team • 07/25/2018
The vulnerability identified as CVE-2006-2017 affects Dnsmasq version 2.29, a widely deployed DNS forwarder and DHCP server commonly found in residential gateways, embedded systems, and small network environments. This issue represents a classic denial of service flaw that can be exploited by remote attackers to disrupt network services. The vulnerability specifically manifests when Dnsmasq processes DHCP client broadcast reply requests, which are standard network communications used by devices to obtain IP configuration information from DHCP servers. The flaw occurs at the protocol parsing level where the software fails to properly handle malformed or unexpected DHCP broadcast responses, leading to application instability and potential system crashes.
The technical root cause of this vulnerability lies in insufficient input validation within Dnsmasq's DHCP processing module. When a malicious actor sends a specially crafted DHCP broadcast reply packet, the software's parsing logic does not adequately sanitize the incoming data before attempting to process it. This lack of proper bounds checking and validation creates a condition where the application encounters unexpected data structures that cause memory corruption or invalid pointer dereferences. According to CWE classification, this vulnerability maps to CWE-129 Input Validation and Representation, specifically involving improper validation of input data during network protocol handling. The flaw demonstrates characteristics of CWE-704 Incorrect Calculation, where the software fails to properly account for edge cases in network packet processing, and CWE-248 Uncaught Exception, as the application does not gracefully handle unexpected input conditions.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise network infrastructure reliability. In environments where Dnsmasq serves as the primary DHCP server, a successful exploitation could result in complete network outages for all devices relying on dynamic IP assignment. This affects both residential networks with multiple connected devices and enterprise environments using embedded appliances. The remote nature of the attack means that adversaries do not require physical access or local network presence to exploit the vulnerability, making it particularly dangerous for network administrators. From an ATT&CK framework perspective, this vulnerability aligns with T1499.004 Network Denial of Service and T1595.001 Network Denial of Service, representing a critical weakness in network infrastructure that can be leveraged for broader operational disruption. The vulnerability affects systems where Dnsmasq operates as a DHCP server, typically found in home routers, small office networks, and embedded network devices, creating a widespread attack surface across multiple network segments.
Mitigation strategies for CVE-2006-2017 should prioritize immediate software updates to versions that have addressed the DHCP processing flaw. Network administrators should implement network segmentation to isolate critical infrastructure from potentially compromised devices, reducing the attack surface available to malicious actors. Additionally, deploying intrusion detection systems capable of monitoring for anomalous DHCP traffic patterns can help identify exploitation attempts before they succeed. The vulnerability highlights the importance of maintaining up-to-date network infrastructure software, as many embedded systems running Dnsmasq may not receive regular security updates. Organizations should also consider implementing network access controls that limit the scope of DHCP broadcast traffic and establish monitoring procedures for detecting service disruptions. The remediation process requires careful coordination to avoid disrupting legitimate network operations while ensuring that all affected systems receive proper patches or replacements. Regular vulnerability assessments should include verification of DHCP server configurations and network device software versions to prevent similar issues from arising in the future.