A first look at the misuse and abuse of the IPv4 Transfer Market The depletion of the unallocated address space in combination with the slow pace of IPv6 deployment have given rise to the IPv4 transfer market, namely the trading of allocated IPv4 prefixes between ASes. While RIRs have established detailed policies in an effort to regulate the IPv4 transfer market for malicious networks such as spammers and bulletproof ASes, IPv4 transfers pose an opportunity to bypass reputational penalties of abusive behaviour since they can obtain clean address space or offload blacklisted address space. Additionally, IP transfers create a window of uncertainty about legitimate ownership of prefixes, which adversaries to hijack parts of the transferred address space. In this paper, we provide the first detailed study of how transferred IPv4 prefixes are misused in the wild by synthesizing an array of longitudinal IP blacklists and lists of prefix hijacking incidents. Our findings yield evidence that the transferred network blocks are used by malicious networks to address botnets and fraudulent sites in much higher rates compared to nontransferred addresses, while the timing of the attacks indicates efforts to evade filtering mechanisms.

Dont Forget to Lock the Front Door! Inferring the Deployment of Source Address Validation of Inbound Traffic This paper concerns the problem of the absence of ingress filtering at the network edge, one of the main causes of important network security issues. Numerous network operators do not deploy the best current practice  Source Address Validation (SAV) that aims at mitigating these issues. We perform the first Internetwide active measurement study to enumerate networks not filtering incoming packets by their source address. The measurement method consists of identifying closed and open DNS resolvers handling requests coming from the outside of the network with the source address from the range assigned inside the network under the test. The proposed method provides the most complete picture of the inbound SAV deployment state at network providers. We reveal that 32 673 Autonomous Systems (ASes) and 197 641 Border Gateway Protocol (BGP) prefixes are vulnerable to spoofing of inbound traffic. Finally, using the data from the Spoofer project and performing an open resolver scan, we compare the filtering policies in both directions.