CVE-2008-3350 in dnsmasq
Summary
by MITRE
dnsmasq 2.43 allows remote attackers to cause a denial of service (daemon crash) by (1) sending a DHCPINFORM while lacking a DHCP lease, or (2) attempting to renew a nonexistent DHCP lease for an invalid subnet as an "unknown client," a different vulnerability than CVE-2008-3214.
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Analysis
by VulDB Data Team • 08/16/2019
The vulnerability identified as CVE-2008-3350 affects dnsmasq version 2.43 and represents a significant denial of service weakness that can be exploited by remote attackers to crash the DNS and DHCP daemon. This vulnerability specifically targets the daemon's handling of DHCP client requests, creating a scenario where legitimate network operations can be disrupted through carefully crafted malicious packets. The flaw demonstrates the critical importance of proper input validation and error handling in network services that operate in untrusted environments where attackers may have direct access to the network infrastructure.
The technical implementation of this vulnerability occurs through two distinct attack vectors that exploit the daemon's DHCP lease management system. The first vector involves sending a DHCPINFORM message without possessing a valid DHCP lease, while the second vector targets attempts to renew a DHCP lease for a subnet that does not exist, particularly when the client is identified as "unknown." Both scenarios trigger memory corruption or improper state handling within the dnsmasq daemon, leading to a complete crash and subsequent service disruption. This vulnerability operates at the network protocol level, specifically targeting the Dynamic Host Configuration Protocol implementation within the DNS masquerade service.
The operational impact of CVE-2008-3350 extends beyond simple service disruption to potentially compromise network availability and stability. When the dnsmasq daemon crashes, all clients relying on that service for DNS resolution and DHCP lease management experience immediate connectivity issues. This affects not only individual devices but entire network segments that depend on the daemon for basic network operations. The vulnerability is particularly concerning because it can be exploited remotely without requiring authentication or elevated privileges, making it accessible to any attacker with network access to the affected network segment. Network administrators may experience significant downtime while investigating and resolving the service disruption.
This vulnerability aligns with CWE-121, which addresses buffer overflow conditions, and demonstrates how improper handling of network protocol messages can lead to daemon crashes. The attack pattern follows techniques described in the MITRE ATT&CK framework under the T1499.004 subtechnique for network denial of service attacks. The flaw represents a classic example of how protocol implementation errors can be exploited to create service availability issues, and it underscores the importance of robust error handling in network services. Organizations running dnsmasq versions prior to the patched release should implement immediate mitigations including service monitoring, automated restart procedures, and network segmentation to limit the impact of potential exploitation.
The vulnerability highlights the broader challenge of maintaining secure network infrastructure services where multiple protocols operate simultaneously. Proper input validation and state management become critical when services must handle various client types and network conditions. This issue emphasizes that even seemingly benign protocol operations can become attack vectors when proper error handling mechanisms are absent. The specific nature of the vulnerability suggests that the dnsmasq implementation did not adequately validate client state before processing DHCP requests, creating an exploitable condition that directly impacts service availability and network stability.