ae91270961
https://hackerone.com/reports/991106 > It’s possible to use UDP gossip protocol to amplify DDoS attacks. An attacker > can spoof IP address in UDP packet when sending PullRequest to the node. > There's no any validation if provided source IP address is not spoofed and > the node can send much larger PullResponse to victim's IP. As I checked, > PullRequest is about 290 bytes, while PullResponse is about 10 kB. It means > that amplification is about 34x. This way an attacker can easily perform DDoS > attack both on Solana node and third-party server. > > To prevent it, need for example to implement ping-pong mechanism similar as > in Ethereum: Before accepting requests from remote client needs to validate > his IP. Local node sends Ping packet to the remote node and it needs to reply > with Pong packet that contains hash of matching Ping packet. Content of Ping > packet is unpredictable. If hash from Pong packet matches, local node can > remember IP where Ping packet was sent as correct and allow further > communication. > > More info: > https://github.com/ethereum/devp2p/blob/master/discv4.md#endpoint-proof > https://github.com/ethereum/devp2p/blob/master/discv4.md#wire-protocol The commit adds a PingCache, which maintains records of remote nodes which have returned a valid response to a ping message, and on-the-fly ping messages pending a pong response from the remote node. When handling pull-requests, those from addresses which have not passed the ping-pong check are filtered out, and additionally ping packets are added for addresses which need to be (re)verified. |
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