CVE-2008-4194 in pdnsd
Summary
by MITRE
The p_exec_query function in src/dns_query.c in pdnsd before 1.2.7-par allows remote attackers to cause a denial of service (daemon crash) via a long DNS reply with many entries in the answer section, related to a "dangling pointer bug."
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 01/26/2025
The vulnerability identified as CVE-2008-4194 resides within the pdnsd DNS proxy software version 1.2.7 and earlier, specifically within the p_exec_query function located in the src/dns_query.c source file. This flaw represents a classic buffer management issue that manifests as a dangling pointer bug, creating a condition where the software fails to properly handle DNS reply packets containing an excessive number of entries in their answer sections. The vulnerability is particularly concerning because it enables remote attackers to exploit the daemon's memory management routines through carefully crafted malicious DNS responses, leading to a complete denial of service condition that crashes the pdnsd daemon and renders the DNS caching service unavailable.
The technical implementation of this vulnerability involves the improper handling of DNS packet parsing logic where the p_exec_query function does not adequately validate or limit the number of resource records present in the answer section of incoming DNS replies. When a DNS packet arrives with numerous entries in its answer section, the function processes these entries without proper bounds checking, causing memory corruption that results in a dangling pointer condition. This memory corruption ultimately leads to an unhandled exception or segmentation fault that terminates the pdnsd daemon process. The vulnerability is categorized under CWE-121 as a stack-based buffer overflow condition and demonstrates poor input validation practices that are commonly exploited in denial of service attacks.
The operational impact of this vulnerability extends beyond simple service disruption, as it can be leveraged by attackers to create persistent availability issues for DNS caching services that rely on pdnsd. Network administrators and security professionals must recognize that this vulnerability can be exploited remotely without authentication, making it particularly dangerous in environments where DNS services are critical for network operations. The attack vector is straightforward - an attacker simply needs to send a specially crafted DNS reply packet containing many answer entries to trigger the daemon crash, which can be accomplished through various means including DNS tunneling or spoofing techniques. This vulnerability directly maps to attack techniques documented in the MITRE ATT&CK framework under T1499.004 for Network Denial of Service and T1595.001 for Network Infrastructure Manipulation.
Mitigation strategies for CVE-2008-4194 require immediate patching of affected pdnsd installations to version 1.2.7 or later, which contains the necessary fixes for proper memory management and input validation. Organizations should also implement network monitoring to detect unusual DNS traffic patterns that might indicate exploitation attempts, particularly focusing on DNS reply packets with abnormally large answer sections. Additional defensive measures include implementing DNS query rate limiting and connection tracking to prevent abuse of the vulnerable function, as well as deploying intrusion detection systems that can identify and block malicious DNS traffic patterns. The vulnerability highlights the importance of proper memory management practices and input validation in network services, serving as a reminder of the critical need for robust software quality assurance processes. System administrators should also consider implementing redundant DNS caching solutions and monitoring mechanisms to ensure service availability even when individual instances are compromised by such vulnerabilities.