The Transmission Control Protocol.

Today's social bots are sophisticated and sometimes menacing. Indeed, their presence can endanger online ecosystems as well as our society.

https://dl.acm.org/doi/pdf/10.1145/2818717

The rise of social bots

The Turing test aimed to recognize the behavior of a human from that of a computer algorithm. Such challenge is more relevant than ever in today's social media context, where limited attention and technology constrain the expressive power of humans, while incentives abound to develop software agents mimicking humans. These social bots interact, often unnoticed, with real people in social media ecosystems, but their abundance is uncertain. While many bots are benign, one can design harmful bots with the goals of persuading, smearing, or deceiving. Here we discuss the characteristics of modern, sophisticated social bots, and how their presence can endanger online ecosystems and our society. We then review current efforts to detect social bots on Twitter. Features related to content, network, sentiment, and temporal patterns of activity are imitated by bots but at the same time can help discriminate synthetic behaviors from human ones, yielding signatures of engineered social tampering.

/pdf/the-rise-of-social-bots-4g4ngytedj.pdf

The Rise of Social Bots

Garbled circuits, a classical idea rooted in the work of Yao, have long been understood as a cryptographic technique, not a cryptographic goal. Here we cull out a primitive corresponding to this technique. We call it a garbling scheme. We provide a provable-security treatment for garbling schemes, endowing them with a versatile syntax and multiple security definitions. The most basic of these, privacy, suffices for two-party secure function evaluation (SFE) and private function evaluation (PFE). Starting from a PRF, we provide an efficient garbling scheme achieving privacy and we analyze its concrete security. We next consider obliviousness and authenticity, properties needed for private and verifiable outsourcing of computation. We extend our scheme to achieve these ends. We provide highly efficient blockcipher-based instantiations of both schemes. Our treatment of garbling schemes presages more efficient garbling, more rigorous analyses, and more modularly designed higher-level protocols.

/pdf/foundations-of-garbled-circuits-f3gqwxe1v8.pdf

Foundations of garbled circuits

The Man-In-The-Middle (MITM) attack is one of the most well known attacks in computer security, representing one of the biggest concerns for security professionals. MITM targets the actual data that flows between endpoints, and the confidentiality and integrity of the data itself. In this paper, we extensively review the literature on MITM to analyse and categorize the scope of MITM attacks, considering both a reference model, such as the open systems interconnection (OSI) model, as well as two specific widely used network technologies, i.e., GSM and UMTS. In particular, we classify MITM attacks based on several parameters, like location of an attacker in the network, nature of a communication channel, and impersonation techniques. Based on an impersonation techniques classification, we then provide execution steps for each MITM class. We survey existing countermeasures and discuss the comparison among them. Finally, based on our analysis, we propose a categorisation of MITM prevention mechanisms, and we identify some possible directions for future research.

A Survey of Man In The Middle Attacks

We present effective off-path DNS cache poisoning attacks, circumventing widely-deployed challenge-response defenses, e.g., transaction identifier randomisation, port and query randomisation. Our attacks depend on the use of UDP to retrieve long DNS responses, resulting in IP fragmentation. We show how attackers are often able to generate such fragmented responses, and then abuse them to inject spoofed, 'poisonous' records, into legitimate DNS responses. We also studied how resolvers, name servers, domains and registrars, can defend against our attacks. The best defense is deployment and enforcement of DNSSEC validation. However, DNSSEC must be deployed correctly by both domain and resolver, which is challenging; we hope our results will catalyse this process, but it will surely take long time. In fact, recent study found less than 1 % of resolvers reject responses upon DNSSEC validation failures. Note also that, ironically, adoption of DNSSEC by a domain, is the main reason for fragmented DNS responses (abused in our attacks). We therefore present several short-term countermeasures, which can complement DNSSEC, especially until DNSSEC deployment is complete. We validated our attacks against popular resolvers (Bind and Unbound), and real domains in the Internet.

Fragmentation Considered Poisonous, or: One-domain-to-rule-them-all.org

Most caching DNS resolvers still rely for their security, against poisoning, on validating that the DNS responses contain some ‘unpredictable’ values, copied from the request These values include the 16 bit identifier field, and other fields, randomised and validated by different ‘patches’ to DNS We investigate the prominent patches, and show how attackers can circumvent all of them, namely:

/pdf/security-of-patched-dns-c7ccbhx3wg.pdf

Security of Patched DNS

The security of Internet-based applications fundamentally relies on the trustworthiness of Certificate Authorities (CAs) We practically demonstrate for the first time that even a weak off-path attacker can effectively subvert the trustworthiness of popular commercially used CAs Our attack targets CAs which use Domain Validation (DV) for authenticating domain ownership; collectively these CAs control 99% of the certificates market The attack utilises DNS Cache poisoning and tricks the CA into issuing fraudulent certificates for domains the attacker does not legitimately own -- namely certificates binding the attacker's public key to a victim domain We discuss short and long term defences, but argue that they fall short of securing DV To mitigate the threats we propose Domain Validation++ (DV++) DV++ replaces the need in cryptography through assumptions in distributed systems While retaining the benefits of DV (automation, efficiency and low costs) DV++ is secure even against Man-in-the-Middle (MitM) attackers Deployment of DV++ is simple and does not require changing the existing infrastructure nor systems of the CAs We demonstrate security of DV++ under realistic assumptions and provide open source access to DV++ implementation

Domain Validation++ For MitM-Resilient PKI

Are We There Yet? On RPKI's Deployment and Security.

As awareness for privacy of Domain Name System (DNS) is increasing, a number of mechanisms for encryption of DNS packets were proposed. We study the prominent defences, focusing on the privacy guarantees, interoperability with the DNS infrastructure, and the efficiency overhead. In particular:•We explore dependencies in DNS and show techniques that utilise side channel leaks, due to transitive trust, allowing to infer information about the target domain in an encrypted DNS packet.•We examine common DNS servers configurations and show that the proposals are expected to encounter deployment obstacles with (at least) 38% of 50K-top Alexa domains and (at least) 12% of the top-level domains (TLDs), and will disrupt the DNS functionality and availability for clients.•We show that due to the non-interoperability with the caches, the proposals for end-to-end encryption may have a prohibitive traffic overhead on the name servers.Our work indicates that further study may be required to adjust the proposals to stand up to their security guarantees, and to make them suitable for the common servers' configurations in the DNS infrastructure. Our study is based on collection and analysis of the DNS traffic of 50K-top Alexa domains and 568 TLDs.

Haya Shulman

Papers

Fragmentation Considered Poisonous, or: One-domain-to-rule-them-all.org

Security of Patched DNS

Domain Validation++ For MitM-Resilient PKI

Are We There Yet? On RPKI's Deployment and Security.

Pretty Bad Privacy: Pitfalls of DNS Encryption