ghsa-jp26-88mw-89qr
Vulnerability from github
Summary
sigstore-java has insufficient verification for a situation where a bundle provides a invalid signature for a checkpoint.
Impact
This bug impacts clients using any variation of KeylessVerifier.verify()
Currently checkpoints are only used to ensure the root hash of an inclusion proof was provided by the log in question. Failing to validate that means a bundle may provide an inclusion proof that doesn't actually correspond to the log in question. This may eventually lead a monitor/witness being unable to detect when a compromised logs are providing different views of themselves to different clients.
There are other mechanisms right now that mitigate this, such as the signed entry timestamp. Sigstore-java currently requires a valid signed entry timestamp. By correctly verifying the signed entry timestamp we can make certain assertions about the log signing the log entry (like the log was aware of the artifact signing event and signed it). Therefore the impact on clients that are not monitors/witnesses is very low.
All cryptographic materials and identity information in the bundle must still be verified for the verification to pass. A valid signed entry timestamp is still required for verification to pass.
sigstore-gradle-plugin and sigstore-maven-plugin are not affected by this as they only provide signing functionality.
Steps To Reproduce
Build the java sigstore-cli at v1.1.0
shell
git clone --branch v1.1.0 git@github.com:sigstore/sigstore-java
cd sigstore-java
./gradlew :sigstore-cli:build
tar -xf sigstore-cli/build/distributions/sigstore-cli-1.1.0-SNAPSHOT.tar --strip-components 1
Create some random blob and sign it
shell
dd bs=1 count=50 </dev/urandom > blob
./bin/sigstore-cli sign --bundle=blob.sigstore.json blob
Modify the checkpoint signature on the bundle, this is the last base64 section in the checkpoint, the following diff just swaps changes the last 3 base64 characters to aaa.
diff
"checkpoint": {
+ "envelope": "rekor.sigstore.dev - 1193050959916656506\n29874050\nhnEOPEa6SDzqJDydU+J96TQyfYfqEpsGg0aVbmfjWDw\u003d\n\n— rekor.sigstore.dev wNI9ajBFAiEA4M7t/9b42FzeArRhC6oRvs7UvKwklaFLYfDDGTi2R4kCIBNc2d0VCyUbs3hd+bI7+0RHhvLOdAqYg7j/3xPe2ZPb\n"
- "envelope": "rekor.sigstore.dev - 1193050959916656506\n29874050\nhnEOPEa6SDzqJDydU+J96TQyfYfqEpsGg0aVbmfjWDw\u003d\n\n— rekor.sigstore.dev wNI9ajBFAiEA4M7t/9b42FzeArRhC6oRvs7UvKwklaFLYfDDGTi2R4kCIBNc2d0VCyUbs3hd+bI7+0RHhvLOdAqYg7j/3xPe2aaa\n"
}
```shell ./bin/sigstore-cli verify --bundle=blob.sigstore.json blob
no errors???!
```
Patches
Patched in v1.2.0 release (patch: https://github.com/sigstore/sigstore-java/commit/23fb4885e6704a5df4977f7acf253a745349edf9) Conformance tests added https://github.com/sigstore/sigstore-conformance/pull/139
Workarounds
Verifiers may chose to verify the checkpoint manually after running KeylessVerifier.verify()
```java
var bundle = Bundle.from(bundleFile, StandardCharsets.UTF_8);
var entry = bundle.getEntries().get(0);
var checkpoint = entry.getVerification().getInclusionProof().parsedCheckpoint();
var signedData = Splitter.on("\n\n").splitToList(entry.getVerification().getInclusionProof().getCheckpoint()).get(0) + "\n";
var tufClient = SigstoreTufClient.builder().usePublicGoodInstance().build(); tufClient.update(); var trustedRoot = tufClient.getSigstoreTrustedRoot(); var tlog = TransparencyLog.find(trustedRoot.getTLogs(), Hex.decode(entry.getLogID()), entry.getIntegratedTimeInstant());
if (!Verifiers.newVerifier(tlog.get().getPublicKey().toJavaPublicKey()).verify(signedData.getBytes(StandardCharsets.UTF_8), checkpoint.getSignatures().get(0).getSignature())) { throw new Exception("Checkpoint signature was invalid"); } ```
{
"affected": [
{
"package": {
"ecosystem": "Maven",
"name": "dev.sigstore:sigstore-java"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "1.2.0"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2024-54140"
],
"database_specific": {
"cwe_ids": [
"CWE-20"
],
"github_reviewed": true,
"github_reviewed_at": "2024-12-05T22:22:49Z",
"nvd_published_at": "2024-12-05T22:15:20Z",
"severity": "LOW"
},
"details": "### Summary\nsigstore-java has insufficient verification for a situation where a bundle provides a invalid signature for a checkpoint.\n\n### Impact\nThis bug impacts clients using any variation of KeylessVerifier.verify()\n\nCurrently checkpoints are only used to ensure the root hash of an inclusion proof was provided by the log in question. Failing to validate that means a bundle may provide an inclusion proof that doesn\u0027t actually correspond to the log in question. This may eventually lead a monitor/witness being unable to detect when a compromised logs are providing different views of themselves to different clients.\n\nThere are other mechanisms right now that mitigate this, such as the signed entry timestamp. Sigstore-java currently requires a valid signed entry timestamp. By correctly verifying the signed entry timestamp we can make certain assertions about the log signing the log entry (like the log was aware of the artifact signing event and signed it). Therefore the impact on clients that are not monitors/witnesses is very low.\n\nAll cryptographic materials and identity information in the bundle must still be verified for the verification to pass. A valid signed entry timestamp is still required for verification to pass.\n\nsigstore-gradle-plugin and sigstore-maven-plugin are not affected by this as they only provide signing functionality.\n\n### Steps To Reproduce\nBuild the java sigstore-cli at v1.1.0\n```shell\ngit clone --branch v1.1.0 git@github.com:sigstore/sigstore-java\ncd sigstore-java\n./gradlew :sigstore-cli:build\ntar -xf sigstore-cli/build/distributions/sigstore-cli-1.1.0-SNAPSHOT.tar --strip-components 1\n```\n\nCreate some random blob and sign it\n```shell\ndd bs=1 count=50 \u003c/dev/urandom \u003e blob\n./bin/sigstore-cli sign --bundle=blob.sigstore.json blob\n```\n\nModify the checkpoint signature on the bundle, this is the last base64 section in the checkpoint, the following diff just swaps changes the last 3 base64 characters to aaa.\n```diff\n\"checkpoint\": {\n+ \"envelope\": \"rekor.sigstore.dev - 1193050959916656506\\n29874050\\nhnEOPEa6SDzqJDydU+J96TQyfYfqEpsGg0aVbmfjWDw\\u003d\\n\\n\u2014 rekor.sigstore.dev wNI9ajBFAiEA4M7t/9b42FzeArRhC6oRvs7UvKwklaFLYfDDGTi2R4kCIBNc2d0VCyUbs3hd+bI7+0RHhvLOdAqYg7j/3xPe2ZPb\\n\"\n- \"envelope\": \"rekor.sigstore.dev - 1193050959916656506\\n29874050\\nhnEOPEa6SDzqJDydU+J96TQyfYfqEpsGg0aVbmfjWDw\\u003d\\n\\n\u2014 rekor.sigstore.dev wNI9ajBFAiEA4M7t/9b42FzeArRhC6oRvs7UvKwklaFLYfDDGTi2R4kCIBNc2d0VCyUbs3hd+bI7+0RHhvLOdAqYg7j/3xPe2aaa\\n\"\n}\n```\n\n```shell\n./bin/sigstore-cli verify --bundle=blob.sigstore.json blob\n# no errors???!\n```\n### Patches\nPatched in v1.2.0 release (patch: https://github.com/sigstore/sigstore-java/commit/23fb4885e6704a5df4977f7acf253a745349edf9)\nConformance tests added https://github.com/sigstore/sigstore-conformance/pull/139\n\n### Workarounds\nVerifiers may chose to verify the checkpoint manually after running `KeylessVerifier.verify()`\n```java\nvar bundle = Bundle.from(bundleFile, StandardCharsets.UTF_8);\nvar entry = bundle.getEntries().get(0);\nvar checkpoint = entry.getVerification().getInclusionProof().parsedCheckpoint();\nvar signedData = Splitter.on(\"\\n\\n\").splitToList(entry.getVerification().getInclusionProof().getCheckpoint()).get(0) + \"\\n\";\n\nvar tufClient = SigstoreTufClient.builder().usePublicGoodInstance().build();\ntufClient.update();\nvar trustedRoot = tufClient.getSigstoreTrustedRoot();\nvar tlog = TransparencyLog.find(trustedRoot.getTLogs(), Hex.decode(entry.getLogID()), entry.getIntegratedTimeInstant());\n\nif (!Verifiers.newVerifier(tlog.get().getPublicKey().toJavaPublicKey()).verify(signedData.getBytes(StandardCharsets.UTF_8), checkpoint.getSignatures().get(0).getSignature())) {\n throw new Exception(\"Checkpoint signature was invalid\");\n}\n```\n",
"id": "GHSA-jp26-88mw-89qr",
"modified": "2024-12-06T00:32:50Z",
"published": "2024-12-05T22:22:49Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/sigstore/sigstore-java/security/advisories/GHSA-jp26-88mw-89qr"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-54140"
},
{
"type": "WEB",
"url": "https://github.com/sigstore/sigstore-conformance/pull/139"
},
{
"type": "WEB",
"url": "https://github.com/sigstore/sigstore-java/commit/23fb4885e6704a5df4977f7acf253a745349edf9"
},
{
"type": "PACKAGE",
"url": "https://github.com/sigstore/sigstore-java"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N",
"type": "CVSS_V4"
}
],
"summary": "sigstore-java has a vulnerability with bundle verification"
}
Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.