Mining pools have been the driving force for ensuring the security of multiple proof-of-work (PoW) cryptocurrencies. Under the de facto protocol Stratum, pools allow miners to collaborate, discover new blocks, and earn rewards collectively. Recently, the blockchain community has been promoting the adoption of a more secure Stratum protocol known as Stratum V2. In this paper, we introduce Erosion, a novel network-level attack that applies to both Stratum and Stratum V2 protocols. The essence of the Erosion attack lies in its ability to disrupt connections between miners and a targeted mining pool, significantly impairing the miners’ contributed PoWs and reducing the victim’s mining power. We also discover a vulnerability in the Stratum V2 protocol that allows the adversary to persistently disrupt a connection by tampering with a single packet, thus enhancing the attack’s stealthiness. Our survey shows that the Erosion adversary can readily execute attacks against a significant majority (e.g., 91%) of mining pools across the top ten cryptocurrencies. We also observe an extreme mining centralization that enables Erosion adversaries to simultaneously target multiple pools and cryptocurrencies. Furthermore, our focused evaluation of pooled mining in Bitcoin reveals that thousands of different adversaries can gain control over the majority of Bitcoin mining power, with one potentially malicious Autonomous System capable of taking down 96% of the total mining power.

Telegram is a popular messenger with more than 550 million active users per month and with a large ecosystem of different clients. The wide adoption of Telegram by protestors relying on private and secure messaging provides motivation for developing a profound understanding of its cryptographic design and how this influences its security properties. Telegram has its own bespoke transport layer security protocol, MTProto 2.0. This protocol was recently subjected to a detailed study by Albrecht et al. (IEEE S&P 2022). They gave attacks on the protocol and its implementations, along with a security proof for a modified version of the protocol.

The Lightning Network (LN) is a widely-adopted off-chain protocol that not only addresses Bitcoin’s scaling problem but also enables anonymous payments. Prior attacks have shown that an adversary controlling several peers at the central position of the network (e.g., by hijacking payment routes) can deanonymize such payments. However, these attacks are highly observable or require many parties to collude.This paper presents Revelio, a stealthier, passive network-level privacy attack against LN that exploits its joint centralization at the application and the network layers. Indeed, network-level adversaries can see most of the LN traffic (e.g., five autonomous systems can see up to 80 % of all observable communication channels) despite the encrypted communication between LN nodes and the widespread usage of Tor. This comprehensive view allows Revelio adversaries not only to estimate the payment amount but also to effectively reduce the anonymity size of its endpoints. We show that the Revelio attack is practical: it perfectly deanonymizes the senders or the receiver in almost one-third of tested payments in today’s LN and underlying network topologies.