unversioned immutable actions wip

Author: KyFaSt

ql/lib/codeql/actions/config/Config.qll

@@ -119,6 +119,17 @@ predicate vulnerableActionsDataModel(
   Extensions::vulnerableActionsDataModel(action, vulnerable_version, vulnerable_sha, fixed_version)
 }
 
+/**
+ * MaD models for vulnerable actions
+ * Fields:
+ *    - action: action name
+ */
+predicate immutableActionsDataModel(
+  string action
+) {
+  Extensions::immutableActionsDataModel(action)
+}
+
 /**
  * MaD models for untrusted git commands
  * Fields:

ql/lib/codeql/actions/config/ConfigExtensions.qll

@@ -58,6 +58,13 @@ extensible predicate vulnerableActionsDataModel(
   string action, string vulnerable_version, string vulnerable_sha, string fixed_version
 );
 
+/**
+ * Holds for actions that are known to be immutable.
+ */
+extensible predicate immutableActionsDataModel(
+  string action
+);
+
 /**
  * Holds for git commands that may introduce untrusted data when called on an attacker controlled branch.
  */

ql/lib/ext/config/immutable_actions.yml

@@ -0,0 +1,22 @@
+extensions:
+  - addsTo:
+      pack: github/actions-all
+      extensible: immutableActionsDataModel
+    data:
+      - ["actions/checkout"]
+      - ["actions/cache"]
+      - ["actions/setup-node"]
+      - ["actions/upload-artifact"]
+      - ["actions/setup-python"]
+      - ["actions/download-artifact"]
+      - ["actions/github-script"]
+      - ["actions/setup-java"]
+      - ["actions/setup-go"]
+      - ["actions/upload-pages-artifact"]
+      - ["actions/deploy-pages"]
+      - ["actions/setup-dotnet"]
+      - ["actions/stale"]
+      - ["actions/labeler"]
+      - ["actions/create-github-app-token"]
+      - ["actions/configure-pages"]
+      - ["octokit/request-action"]

ql/src/Security/CWE-829/UnversionedImmutableAction.md

@@ -0,0 +1,27 @@
+# Unpinned tag for 3rd party Action in workflow
+
+## Description
+
+Using a tag for a 3rd party Action that is not pinned to a commit can lead to executing an untrusted Action through a supply chain attack.
+
+## Recommendations
+
+Pinning an action to a full length commit SHA is currently the only way to use an action as an immutable release. Pinning to a particular SHA helps mitigate the risk of a bad actor adding a backdoor to the action's repository, as they would need to generate a SHA-1 collision for a valid Git object payload. When selecting a SHA, you should verify it is from the action's repository and not a repository fork.
+
+## Examples
+
+### Incorrect Usage
+
+```yaml
+- uses: tj-actions/changed-files@v44
+```
+
+### Correct Usage
+
+```yaml
+- uses: tj-actions/changed-files@c65cd883420fd2eb864698a825fc4162dd94482c # v44
+```
+
+## References
+
+- [Using third-party actions](https://docs.github.com/en/actions/security-for-github-actions/security-guides/security-hardening-for-github-actions#using-third-party-actions)

ql/src/Security/CWE-829/UnversionedImmutableAction.ql

@@ -0,0 +1,38 @@
+/**
+ * @name Unversioned Immutable Action
+ * @description Using an Immutable Action without a semantic version tag opts out of the protections of Immutable Action
+ * @kind problem
+ * @security-severity 5.0
+ * @problem.severity recommendation
+ * @precision high
+ * @id actions/unversioned-immutable-action
+ * @tags security
+ *       actions
+ *       external/cwe/cwe-829
+ */
+
+import actions
+
+bindingset[version]
+private predicate isSemanticVersioned(string version) { version.regexpMatch("^v[0-9]+(\\.[0-9]+)*(\\.[xX])?$") }
+
+bindingset[repo]
+private predicate isTrustedOrg(string repo) {
+  exists(string org | org in ["actions", "github", "advanced-security", "octokit"] | repo.matches(org + "/%"))
+}
+
+from UsesStep uses, string repo, string version, Workflow workflow, string name
+where
+  uses.getCallee() = repo and
+  uses.getEnclosingWorkflow() = workflow and
+  (
+    workflow.getName() = name
+    or
+    not exists(workflow.getName()) and workflow.getLocation().getFile().getBaseName() = name
+  ) and
+  uses.getVersion() = version and
+  not isTrustedOrg(repo) and
+  not isPinnedCommit(version)
+select uses.getCalleeNode(),
+  "Unpinned 3rd party Action '" + name + "' step $@ uses '" + repo + "' with ref '" + version +
+    "', not a pinned commit hash", uses, uses.toString()