Andrew Cagney

Libreswan fails to correctly verify the authentication hash length when the SIG payload of an IKEv1 packet is encoded using PKCS #1 RSA Encryption. This occurs within the `RSA authenticate hash signature raw rsa()` function. A remote attacker can exploit this using a variation of the Bleichenbacher attack—a cryptographic attack targeting RSA encryption—to forge the SIG payload when small public exponents (such as `e=3`) are used, potentially leading to impersonation. Furthermore, by encoding a hash shorter than expected in the SIG payload, a remote attacker can trigger an assertion that causes the daemon to abort and restart, resulting in a sustained denial-of-service. Remote code execution is not possible, and X.509 certificate verifications of remote IKE peers remain unaffected.

Libreswan fails to correctly verify the DER encoding of the ASN.1 digest within the IKEv2 AUTH payload when using RSASSA-PKCS1-v1 5. This occurs in the `RSA authenticate hash signature pkcs1 1 5 rsa()` function. A remote attacker can exploit this using a variation of the Bleichenbacher attack—a method of attacking RSA encryption—to forge the AUTH payload when small public exponents (such as `e=3`) are used, allowing for impersonation. Furthermore, an attacker can cause a denial-of-service by encoding a hash shorter than expected in the AUTH payload, which triggers an assertion that causes the daemon to abort and restart. Remote code execution is not possible, and X.509 certificate verifications of the remote IKE peer remain unaffected.