![]() The BN_mod_sqrt() function, which computes a modular square root, contains a bug that can cause it to loop forever for non-prime moduli. ![]() Use of a Broken or Risky Cryptographic Algorithm In order for an OpenSSL 3.0 endpoint to use this ciphersuite the following must have occurred: 1) OpenSSL must have been compiled with the (non-default) compile time option enable-weak-ssl-ciphers 2) OpenSSL must have had the legacy provider explicitly loaded (either through application code or via configuration) 3) The ciphersuite must have been explicitly added to the ciphersuite list 4) The libssl security level must have been set to 0 (default is 1) 5) A version of SSL/TLS below TLSv1.3 must have been negotiated 6) Both endpoints must negotiate the RC4-MD5 ciphersuite in preference to any others that both endpoints have in common Fixed in OpenSSL 3.0.3 (Affected 3.0.0,3.0.1,3.0.2). This ciphersuite will never be used if TLSv1.3 has been negotiated. This ciphersuite is not compiled by default in OpenSSL 3.0, and is not available within the default provider or the default ciphersuite list. In order for this attack to work both endpoints must legitimately negotiate the RC4-MD5 ciphersuite. an attacker cannot decrypt data that has been encrypted using this ciphersuite - they can only modify it. The confidentiality of data is not impacted by this issue, i.e. Note that in the absence of an attacker this bug means that an OpenSSL 3.0 endpoint communicating with a non-OpenSSL 3.0 endpoint will fail to complete the handshake when using this ciphersuite. In this case both clients and servers could be affected, regardless of the application protocol. If both endpoints are OpenSSL 3.0 then the attacker could modify data being sent in both directions. Therefore, in such a case, only an OpenSSL 3.0 server would be impacted when talking to a non-OpenSSL 3.0 client. ![]() Many application protocols require data to be sent from the client to the server first. Note that data sent from an OpenSSL 3.0 endpoint to a non-OpenSSL 3.0 endpoint will always be rejected by the recipient and the connection will fail at that point. An attacker could exploit this issue by performing a man-in-the-middle attack to modify data being sent from one endpoint to an OpenSSL 3.0 recipient such that the modified data would still pass the MAC integrity check. This makes the MAC key trivially predictable. The OpenSSL 3.0 implementation of the RC4-MD5 ciphersuite incorrectly uses the AAD data as the MAC key. In this case the incorrect successful response will also be accompanied by error messages showing the failure and contradicting the apparently successful result. When verifying an ocsp response with the "-no_cert_checks" option the command line application will report that the verification is successful even though it has in fact failed. This issue also impacts the command line OpenSSL "ocsp" application. The normal expected return value in this case would be 0. In this case the `OCSP_basic_verify` function will return a negative value (indicating a fatal error) in the case of a certificate verification failure. It is anticipated that most users of `OCSP_basic_verify` will not use the OCSP_NOCHECKS flag. In the case where the (non-default) flag OCSP_NOCHECKS is used then the response will be positive (meaning a successful verification) even in the case where the response signing certificate fails to verify. The function `OCSP_basic_verify` verifies the signer certificate on an OCSP response.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |