CVE-2004-2252 in Security Linux
Summary
by MITRE
The firewall in Astaro Security Linux before 4.024 sends responses to SYN-FIN packets, which makes it easier for remote attackers to obtain information about the system and construct specialized attacks.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 07/17/2017
The vulnerability described in CVE-2004-2252 affects the firewall implementation within Astaro Security Linux versions prior to 4.024, representing a significant weakness in network traffic handling that directly impacts system security posture. This issue stems from the firewall's improper response behavior to specific TCP packet combinations, creating exploitable conditions that adversaries can leverage for reconnaissance and attack development. The flaw exists at the network protocol level where the firewall fails to properly handle SYN-FIN packet sequences, which are legitimate TCP communication patterns that should be processed without generating responses.
The technical implementation of this vulnerability involves the firewall's TCP state machine processing logic where it incorrectly responds to SYN-FIN packets that combine both the synchronization and finish flags in a single packet. This abnormal behavior violates standard TCP connection handling procedures and creates predictable response patterns that attackers can analyze to infer system configuration details. The firewall's response mechanism essentially provides attackers with information about the system's network stack implementation, including potentially revealing whether the system is actively running a firewall, the specific TCP stack behavior, and general system architecture characteristics.
From an operational impact perspective, this vulnerability significantly increases the attack surface for remote adversaries who can use the information disclosure characteristics to plan more sophisticated attacks against the target system. The ability to gather system information through simple packet analysis makes this vulnerability particularly dangerous as it requires minimal technical expertise to exploit, enabling even less sophisticated attackers to gain valuable intelligence about the target environment. This information can be used to tailor subsequent attacks, potentially leading to further exploitation opportunities such as port scanning, service enumeration, or even more advanced exploitation techniques that depend on knowing the underlying system behavior.
The vulnerability aligns with CWE-119, which addresses weaknesses in memory handling and improper handling of network protocol states, and demonstrates characteristics consistent with ATT&CK technique T1046, which involves network service scanning. Organizations affected by this vulnerability should immediately implement mitigation strategies including upgrading to Astaro Security Linux version 4.024 or later, where the firewall's TCP handling has been corrected to properly ignore SYN-FIN packets without generating responses. Network administrators should also consider implementing additional monitoring to detect unusual packet patterns that might indicate exploitation attempts, while ensuring that all network devices maintain current security patches and configurations to prevent similar issues from arising in other components of the security infrastructure.
This particular vulnerability highlights the importance of proper TCP state machine implementation in firewall systems and demonstrates how seemingly minor protocol handling issues can create significant security risks. The flaw represents a classic case of inadequate input validation and protocol compliance where the firewall fails to properly handle edge cases in TCP packet processing, creating information leakage that can be exploited by remote attackers. Organizations should conduct thorough security assessments of their firewall configurations and ensure that all network security devices properly implement standard TCP handling procedures to prevent similar information disclosure vulnerabilities from compromising their security posture.