-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 Hello, folks, The United Kingdom's Centre for the Protection of National Infrastructure has just released the document "Security Assessment of the Transmission Control Protocol (TCP)", on which I have had the pleasure to work during the last few years. The motivation to produce this document is explained in the Preface of the document as follows: - ---- cut here ---- The TCP/IP protocol suite was conceived in an environment that was quite different from the hostile environment they currently operate in. However, the effectiveness of the protocols led to their early adoption in production environments, to the point that to some extent, the current world's economy depends on them. While many textbooks and articles have created the myth that the Internet protocols were designed for warfare environments, the top level goal for the DARPA Internet Program was the sharing of large service machines on the ARPANET. As a result, many protocol specifications focus only on the operational aspects of the protocols they specify, and overlook their security implications. While the Internet technology evolved since it early inception, the Internet's building blocks are basically the same core protocols adopted by the ARPANET more than two decades ago. During the last twenty years, many vulnerabilities have been identified in the TCP/IP stacks of a number of systems. Some of them were based on flaws in some protocol implementations, affecting only a reduced number of systems, while others were based in flaws in the protocols themselves, affecting virtually every existing implementation. Even in the last couple of years, researchers were still working on security problems in the core protocols. The discovery of vulnerabilities in the TCP/IP protocol suite usually led to reports being published by a number of CSIRTs (Computer Security Incident Response Teams) and vendors, which helped to raise awareness about the threats and the best mitigations known at the time the reports were published. Unfortunately, this also led to the documentation of the discovered protocol vulnerabilities being spread among a large number of documents, which are sometimes difficult to identify. For some reason, much of the effort of the security community on the Internet protocols did not result in official documents (RFCs) being issued by the IETF (Internet Engineering Task Force). This basically led to a situation in which "known" security problems have not always been addressed by all vendors. In addition, in many cases vendors have implemented quick "fixes" to the identified vulnerabilities without a careful analysis of their effectiveness and their impact on interoperability. Producing a secure TCP/IP implementation nowadays is a very difficult task, in part because of the lack of a single document that serves as a security roadmap for the protocols. Implementers are faced with the hard task of identifying relevant documentation and differentiating between that which provides correct advice, and that which provides misleading advice based on inaccurate or wrong assumptions. There is a clear need for a companion document to the IETF specifications that discusses the security aspects and implications of the protocols, identifies the existing vulnerabilities, discusses the possible countermeasures, and analyses their respective effectiveness. This document is the result of a security assessment of the IETF specifications of the Transmission Control Protocol (TCP), from a security point of view. Possible threats are identified and, where possible, countermeasures are proposed. Additionally, many implementation flaws that have led to security vulnerabilities have been referenced in the hope that future implementations will not incur the same problems. This document does not aim to be the final word on the security aspects of TCP. On the contrary, it aims to raise awareness about a number of TCP vulnerabilities that have been faced in the past, those that are currently being faced, and some of those that we may still have to deal with in the future. Feedback from the community is more than encouraged to help this document be as accurate as possible and to keep it updated as new vulnerabilities are discovered. - ---- cut here ---- The document is available at CPNI's web site: http://www.cpni.gov.uk/Products/technicalnotes/Feb-09-security-assessment-TC... Additionally, I have posted a copy of the document on my personal web site: http://www.gont.com.ar I would like to take the chance to thank NetBSD's Christos Zoulas for his contribution in improving this document. Any comments will be more than welcome. Kind regards, - -- Fernando Gont e-mail: fernando@gont.com.ar || fgont@acm.org PGP Fingerprint: 7809 84F5 322E 45C7 F1C9 3945 96EE A9EF D076 FFF1 -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (MingW32) iQEcBAEBCAAGBQJJmu6GAAoJEJbuqe/Qdv/xzx8IAK/FlZYWi0RDnj/e0UcjIEUY I08k+y8OjYuiE3AOwrKLUAmadHTdk4uE4Jam+3qwhKAxscIrV4HWcmUXaLymcuNb It+kjbP1UAyTcGzz/AVDCY3Ekzs89cHjoM5gcQOOnc6IxEaQt1LiWA1NTg8vZWYE iON2fbOd24QseFQBYZgfP21uhIclgZ1erXMSeGjqEyQWr99vH177Y/DMrt/kwdRT S1GEqFalr6xM0XLrNwuwzIGW245mzAfvr6K22D+b4xofKhZoZvyRkibixwqOas9p abxxNbdGCJ9LqTEPKfpX50odjT70yFsdXg1PJgfl5v3+b9aolh/SFSXK8SkkxBo= =hHSj -----END PGP SIGNATURE-----