CVE-2022-23628
Vulnérabilité moyenne dans opa (open-policy-agent)
Description
OPA is an open source, general-purpose policy engine. Under certain conditions, pretty-printing an abstract syntax tree (AST) that contains synthetic nodes could change the logic of some statements by reordering array literals. Example of policies impacted are those that parse and compare web paths. **All of these** three conditions have to be met to create an adverse effect: 1. An AST of Rego had to be **created programmatically** such that it ends up containing terms without a location (such as wildcard variables). 2. The AST had to be **pretty-printed** using the `github.com/open-policy-agent/opa/format` package. 3. The result of the pretty-printing had to be **parsed and evaluated again** via an OPA instance using the bundles, or the Golang packages. If any of these three conditions are not met, you are not affected. Notably, all three would be true if using **optimized bundles**, i.e. bundles created with `opa build -O=1` or higher. In that case, the optimizer would fulfil condition (1.), the result of that would be pretty-printed when writing the bundle to disk, fulfilling (2.). When the bundle was then used, we'd satisfy (3.). As a workaround users may disable optimization when creating bundles.
Gravité et risque d'exploitation
CVE-2022-23628 obtient un score CVSS de 6.3/10, soit une gravité moyenne. Selon le modèle EPSS, la probabilité qu'elle soit exploitée dans les 30 prochains jours est de 1.03 %, ce qui la place devant 63.0 % des CVE référencées.
Que faire ?
- Vérifiez si opa (versions >= 0.33.1, < 0.37.0) 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/open-policy-agent/opa/security/advisories/GHSA-hcw3-j74m-qc58
- https://github.com/open-policy-agent/opa/pull/3851
- https://github.com/open-policy-agent/opa/commit/932e4ffc37a590ace79e9b75ca4340288c220239
- https://github.com/open-policy-agent/opa/commit/bfd984ddf93ef2c4963a08d4fdadae0bcf1a3717
