AWS-LC has Timing Side-Channel in AES-CCM Tag Verification

Summary

AWS-LC is an open-source, general-purpose cryptographic library.

Impact

Observable timing discrepancy in AES-CCM decryption in AWS-LC allows an unauthenticated user to potentially determine authentication tag validity via timing analysis.

The impacted implementations are through the EVP CIPHER API: EVP_aes_128_ccm, EVP_aes_192_ccm, and EVP_aes_256_ccm.

Customers of AWS services do not need to take action. aws-lc-sys and aws-lc-fips-sys contain code from AWS-LC. Applications using aws-lc-sys or aws-lc-fips-sys should upgrade to the most recent releases of aws-lc-sys or aws-lc-fips-sys.

Impacted versions:

• aws-lc-sys versions: >= 0.14.0, < 0.38.0
• aws-lc-fips-sys versions: >= v0.13.0, < 0.13.12.

Patches

The patch is included in aws-lc-sys v.0.38.0 and aws-lc-fips-sys v0.13.12.

Workarounds

In the special cases of using AES-CCM with (M=4, L=2), (M=8, L=2), or (M=16, L=2), applications can workaround this issue by using AES-CCM through the EVP AEAD API using implementations EVP_aead_aes_128_ccm_bluetooth, EVP_aead_aes_128_ccm_bluetooth_8, and, EVP_aead_aes_128_ccm_matter respectively.

Otherwise, there is no workaround and applications using aws-lc-sys or aws-lc-fips-sys should upgrade to the most recent releases of aws-lc-sys or aws-lc-fips-sys.

Resources

If there are any questions or comments about this advisory, contact [AWS/Amazon] Security via thevulnerability reporting page or directly via email to [email protected]. Please do not create a public GitHub issue.

Acknowledgement

AWS-LC would like to thank Joshua Rogers (https://joshua.hu/) for collaborating on this issue through the coordinated vulnerability disclosure process.