Samourai Wallet Stonewallx2 0.99.98e allows a denial of service via a P2P coinjoin. The attacker and victim must follow each others paynym. Then, the victim must try to collaborate with the attacker for a Stonewallx2 transaction. Next, the attacker broadcasts a tx, spending the inputs used in Stonewallx2 before the victim can broadcast the collaborative transaction. The attacker does not signal opt in RBF, and uses the lowest fee rate. This would result in the victim being unable to perform Stonewallx2. (Note that the attacker could use multiple paynyms.)
The product does not properly control the allocation and maintenance of a limited resource.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Samourai | Kayako | 0.99.98e (including) | 0.99.98e (including) |
Mitigation of resource exhaustion attacks requires that the target system either:
The first of these solutions is an issue in itself though, since it may allow attackers to prevent the use of the system by a particular valid user. If the attacker impersonates the valid user, they may be able to prevent the user from accessing the server in question.
The second solution is simply difficult to effectively institute – and even when properly done, it does not provide a full solution. It simply makes the attack require more resources on the part of the attacker.