CVE-2023-38701
Vulnérabilité critique dans hydra (input-output-hk)
Description
Hydra is the layer-two scalability solution for Cardano. Users of the Hydra head protocol send the UTxOs they wish to commit into the Hydra head first to the `commit` validator, where they remain until they are either collected into the `head` validator or the protocol initialisation is aborted and the value in the committed UTxOs is returned to the users who committed them. Prior to version 0.12.0, the `commit` validator contains a flawed check when the `ViaAbort` redeemer is used, which allows any user to spend any UTxO which is at the validator arbitrarily, meaning an attacker can steal the funds that users are trying to commit into the head validator. The intended behavior is that the funds must be returned to the user which committed the funds and can only be performed by a participant of the head. The `initial` validator also is similarly affected as the same flawed check is performed for the `ViaAbort` redeemer. Due to this issue, an attacker can steal any funds that user's try to commit into a Hydra head. Also, an attacker can prevent any Hydra head from being successfully opened. It does not allow an attacker to take funds which have been successfully collected into and currently reside in the `head` validator. Version 0.12.0 contains a fix for this issue.
Gravité et risque d'exploitation
CVE-2023-38701 obtient un score CVSS de 9.1/10, soit une gravité critique. Selon le modèle EPSS, la probabilité qu'elle soit exploitée dans les 30 prochains jours est de 1.13 %, ce qui la place devant 65.9 % des CVE référencées.
Que faire ?
- Vérifiez si hydra (versions < 0.12.0) est présent sur votre parc.
- Appliquez le correctif ou la version corrigée indiqués dans les références de l'éditeur.
- À défaut de correctif, limitez l'exposition (filtrage réseau, désactivation du composant).
- Automatisez la détection : les agents CVE Heimdall (gratuits, open source) corrèlent l'inventaire de vos serveurs avec la base CVE.
Références
- https://github.com/input-output-hk/hydra/security/advisories/GHSA-6x9v-7x5r-w8w6
- https://github.com/input-output-hk/hydra/blob/master/CHANGELOG.md#0120---2023-08-18
- https://github.com/input-output-hk/hydra/blob/master/hydra-plutus/src/Hydra/Contract/Commit.hs#L94-L97
- https://github.com/input-output-hk/hydra/blob/master/hydra-plutus/src/Hydra/Contract/Util.hs#L32-L42