In Meshtastic, an attacker can spoof licensed amateur flag for a node

Summary

Meshtastic is an open source mesh networking solution. In the current Meshtastic architecture, a Node is identified by their NodeID, generated from the MAC address, rather than their public key. This aspect downgrades the security, specifically by abusing the HAM mode which doesn't use encryption. An attacker can, as such, forge a NodeInfo on behalf of a victim node advertising that the HAM mode is enabled. This, in turn, will allow the other nodes on the mesh to accept the new information and overwriting the NodeDB. The other nodes will then only be able to send direct messages to the victim by using the shared channel key instead of the PKC. Additionally, because HAM mode by design doesn't provide any confidentiality or authentication of information, the attacker could potentially also be able to change the Node details, like the full name, short code, etc. To keep the attack persistent, it is enough to regularly resend the forged NodeInfo, in particular right after the victim sends their own. A patch is available in version 2.7.6.834c3c5.