| Internet-Draft | SAV Security | March 2023 |
| Guo, et al. | Expires 10 September 2023 | [Page] |
The new Source Address Validation(SAV) mechanism must not introduce additional security vulnerabilities or risks, and the SAV mechanism should ensure the integrity and trusted origin of the protocol packets that deliver the required SAV information. This document explores the use of blockchain technology to enhance the security of the SAV mechanism itself without modifying existing protocols to ensure the accuracy of the generated SAV rules.¶
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 8174 [RFC8174].¶
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SAV rules are generated based on routing information (FIB/RIB) or non-routing information. If the routing information is poisoned by an attacker, then there will be no way to verify the authenticity of the routing information and the generated SAV rules will be incorrect. Many legitimate packets may be improperly discarded or illegal packets with spoofed source addresses may be improperly allowed. Overall, SAVNET faces similar security threats to BGP, and if the SAV mechanism or protocol requires information exchange, consideration should be given to avoiding routing information tampering or injection.¶
SAV: Source Address Validation, i.e., validating the authenticity of a packet's source IP address.¶
SAV rule: The filtering rule generated by inter-domain SAV mechanisms that determines valid incoming interfaces for a specific source prefix.¶
RPKI: Resource Public Key Infrastructure,an opt-in service that provides security for Internet routing.¶
Improper block: Cases when packets with legitimate source addresses are improperly blocked.¶
Improper permit: Cases when packets with spoofed source addresses are improperly permitted.¶
The main security threats to SAV come from the following areas.¶
The basic idea of RPKI is to construct a PKI (public key infrastructure) to accomplish the authentication of ownership and usage of IP address prefixes and ASNs. It helps routers verify the authenticity of BGP messages by issuing and certifying digital certificates and digital signatures, thus enhancing the security of the BGP protocol and avoiding Internet routing hijacking. However, RPKI cannot resist malicious acts initiated by CAs for the benefit of countries and organizations, and the tree structure of RPKI has the defect of single point of failure, and the whole network may be paralyzed after the attack of high-level CAs, so RPKI has the problem of being centralized and tamperable. In addition, RPKI also has a limited scale of global deployment due to its complex protocol mechanism and high processing overhead.¶
The existing routing protocols cannot guarantee the integrity of AS prefix advertisements and cannot authenticate whether the AS advertisement IP prefix authorization is legitimate. This lack of authenticated unconditional trust can be used by malicious nodes to forge and advertise false or non-compliant AS advertisement information through replay attacks or message injection attacks, resulting in network prefix information, network topology information, AS path information and other key information being hijacked, impersonated, stolen, and tampered with by attackers, which in turn leads to the delivery and proliferation of false routing information, causing security events such as traffic eavesdropping and traffic black holes.¶
After gaining control of the legitimate router through the attack, the attacker disguises the malicious router as a peer node of another router to establish a session with that router, propagating false advertisement messages or tampering with legitimate advertisement messages, which will not only destroy the SAV function but also affect the entire routing domain.¶
As a distributed ledger system of the new generation of Internet, blockchain can record, encrypt and authenticate the whole life cycle transactions of data assets on the Internet in a distributed way. Its security is "endorsed" by the cryptography algorithm used by blockchain technology. After verification, each transaction interaction process can be permanently stored in the distributed database (block). Once verified, it will be shared, anonymous and tamper-proof, and easy to query.¶
Blockchain technology, due to its natural attributes of decentralization, tamper-proof and traceability, is supported by distributed node authentication and consensus mechanisms, allowing any two nodes in a distributed network to reach an unmediated trust. Another advantage of applying blockchain to SAV is that it can add additional security without changing the BGP protocol, and by using blockchain SAV can be protected in several ways.¶
The decentralized, tamper-proof and traceability features of blockchain enable it to solve the centralized and tamper-proof problems of RPKI. Through the two functions of resource transaction record and resource retrieval of blockchain's smart contract technology, the IP address and ASN registration and allocation information are recorded, and the tracking of their usage is supported, so as to realize the authorization authentication of IP address and ASN network resources, prevent the security threat of prefix hijacking and avoid the repeated allocation of resources.¶
The blockchain smart contract technology is used to record the process of IP address authorization. When the AS prefix advertisement is required, the prefix advertisement of the source AS can be stored on the blockchain as transaction information. After receiving the source AS advertisement information, the destination AS determines the integrity of the received AS advertisement information through the transaction information saved on the chain. In this way, the destination AS can verify the validity of the AS advertisement information, and then determine whether there is any unauthorized change attempt, and whether the resource is repeatedly allocated, so as to avoid tampering with the AS advertisement information and prefix hijacking.¶
Store the routing topology relationship in the blockchain. When the AS discovers the malicious advertisement information of the AS through the blockchain verification, the network location of the malicious router can be located in a timely manner by combining the advertisement information source and the routing topology relationship stored in the blockchain to avoid the malicious router causing greater harm to the network. Routing topology is stored in the blockchain through consensus mechanism. Any modification and update of topology data in the blockchain requires the consent of most nodes in the blockchain network to avoid malicious modification of routing topology by a few malicious routers.¶
There could be new blockchain related attacks that SAV would experience if blockchain were to be added into SAV's policy system. We will explore some of those here or in a new draft.¶
TBD¶