CVE-2005-1519 in Squid
Summary
by MITRE
Squid 2.5 STABLE9 and earlier, when the DNS client port is unfiltered and the environment does not prevent IP spoofing, allows remote attackers to spoof DNS lookups.
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Analysis
by VulDB Data Team • 07/02/2019
The vulnerability identified as CVE-2005-1519 affects Squid proxy server versions 2.5 STABLE9 and earlier, presenting a significant security risk related to DNS resolution mechanisms. This flaw specifically manifests when the DNS client port remains unfiltered and the system environment does not adequately prevent IP spoofing attacks. The vulnerability stems from insufficient validation of DNS response sources, allowing malicious actors to manipulate DNS lookup results through spoofing techniques. The impact extends beyond simple data manipulation as it can potentially lead to complete DNS cache poisoning, where attackers can redirect network traffic to malicious destinations.
The technical implementation of this vulnerability resides in Squid's DNS resolution process, which fails to properly validate the authenticity of DNS responses received from upstream servers. When the DNS client port is left unfiltered, attackers can exploit this by sending forged DNS responses that appear to originate from legitimate DNS servers. This occurs because Squid does not adequately verify the source IP addresses of incoming DNS responses or implement proper response validation mechanisms. The vulnerability aligns with CWE-284, which addresses improper access control in network protocols, and CWE-290, which covers authentication bypass through spoofing attacks. The flaw essentially creates a trust relationship that can be easily manipulated by remote attackers who possess knowledge of the network topology or can perform network-level interception.
From an operational standpoint, this vulnerability poses severe risks to organizations relying on Squid as their primary proxy server. Attackers can leverage this weakness to redirect users to malicious websites, perform man-in-the-middle attacks, or inject malicious content into network traffic. The impact is particularly concerning because DNS spoofing can affect any application or service that depends on proper DNS resolution for network connectivity. This vulnerability enables attackers to compromise the integrity of DNS lookups across the entire network segment that relies on the vulnerable Squid proxy. The attack vector is particularly dangerous because it requires minimal privileges and can be executed remotely, making it attractive to threat actors seeking to establish persistent access or conduct large-scale phishing campaigns.
Mitigation strategies for CVE-2005-1519 should focus on implementing proper network filtering and access controls around the DNS client port. Organizations should configure firewalls to block unsolicited DNS responses and ensure that the Squid proxy server operates in an environment where IP spoofing is prevented through proper network segmentation. The most effective remediation involves upgrading to Squid versions beyond 2.5 STABLE9 where the DNS validation mechanisms have been improved. Network administrators should also implement DNS security measures such as DNSSEC to provide additional layers of protection against spoofing attacks. According to ATT&CK framework, this vulnerability maps to technique T1071.004 for application layer protocol: DNS and T1566 for credential access through phishing, as the DNS spoofing can lead to credential theft through redirected authentication portals. Organizations should also consider implementing network monitoring solutions to detect anomalous DNS traffic patterns that may indicate spoofing attempts. The vulnerability demonstrates the critical importance of proper input validation and source authentication in network protocols, aligning with security best practices outlined in NIST SP 800-53 for secure network design and implementation.