CVE-2008-4099 in python-dns
Summary
by MITRE
PyDNS (aka python-dns) before 2.3.1-4 in Debian GNU/Linux does not use random source ports or transaction IDs for DNS requests, which makes it easier for remote attackers to spoof DNS responses, a different vulnerability than CVE-2008-1447.
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Analysis
by VulDB Data Team • 08/02/2021
The vulnerability identified as CVE-2008-4099 affects PyDNS, also known as python-dns, a popular Python library used for DNS resolution operations within various network applications and security tools. This flaw exists specifically in Debian GNU/Linux distributions where the PyDNS package version prior to 2.3.1-4 is installed. The issue stems from the library's failure to implement proper randomization mechanisms for source ports and transaction IDs during DNS query transmission, creating significant security implications for network communications.
The technical flaw in PyDNS lies in its predictable DNS query generation behavior where the library uses fixed or insufficiently randomized source ports and transaction IDs when initiating DNS requests. This predictable pattern allows malicious actors to craft spoofed DNS responses that appear legitimate to the vulnerable system, as the attacker can anticipate the exact transaction ID and source port that will be used in subsequent DNS queries. This vulnerability operates at the DNS protocol level and specifically targets the integrity verification mechanisms that DNS clients use to validate response authenticity. The flaw is particularly concerning because it enables man-in-the-middle attacks where attackers can intercept and manipulate DNS traffic without requiring additional privileges or complex attack vectors.
The operational impact of this vulnerability extends beyond simple DNS spoofing capabilities and can severely compromise network security infrastructure. Systems utilizing vulnerable PyDNS versions become susceptible to various attack scenarios including DNS cache poisoning, where attackers can inject false DNS records into caches, redirecting users to malicious websites, or perform more sophisticated attacks such as credential harvesting and data exfiltration. The vulnerability affects any application or service that relies on PyDNS for DNS resolution, potentially including web applications, network monitoring tools, security scanners, and automated systems that depend on accurate DNS lookups. This creates a broad attack surface where even seemingly innocuous applications could serve as entry points for more extensive network compromises.
Mitigation strategies for CVE-2008-4099 primarily involve updating to PyDNS version 2.3.1-4 or later, which properly implements randomization of source ports and transaction IDs in DNS queries. Organizations should conduct thorough inventory assessments to identify all systems running vulnerable PyDNS versions and prioritize updates accordingly. Network administrators should also consider implementing additional security measures such as DNSSEC validation where possible, though this requires proper infrastructure support and may not be available in all environments. The vulnerability aligns with CWE-310, which addresses cryptographic weaknesses, specifically targeting the lack of proper randomization in network protocols. From an ATT&CK framework perspective, this vulnerability maps to techniques involving DNS tunneling and credential access, as attackers can leverage the spoofing capabilities to redirect traffic and potentially harvest authentication credentials from compromised systems. System administrators should also consider implementing network segmentation and monitoring solutions to detect anomalous DNS traffic patterns that might indicate active exploitation attempts.