OpenSSL is een bekend beveiligingsprogramma dat encryptiefuncties aanbiedt. Het bevat een implementatie van de tls- en ssl-protocollen, waarmee data versleuteld kan worden verstuurd en ontvangen. Voor meer informatie verwijzen we door naar deze pagina. De ontwikkelaars hebben een nieuwe versie uitgebracht met 1.0.2n als versieaanduiding. De bijbehorende lijst met veranderingen laat zien dat er twee beveiligingslekken zijn aangepakt:
Changes between 1.0.2m and 1.0.2n
- Read/write after SSL object in error state - OpenSSL 1.0.2 (starting from version 1.0.2b) introduced an "error state" mechanism. The intent was that if a fatal error occurred during a handshake then OpenSSL would move into the error state and would immediately fail if you attempted to continue the handshake. This works as designed for the explicit handshake functions (SSL_do_handshake(), SSL_accept() and SSL_connect()), however due to a bug it does not work correctly if SSL_read() or SSL_write() is called directly. In that scenario, if the handshake fails then a fatal error will be returned in the initial function call. If SSL_read()/SSL_write() is subsequently called by the application for the same SSL object then it will succeed and the data is passed without being decrypted/encrypted directly from the SSL/TLS record layer.
In order to exploit this issue an application bug would have to be present that resulted in a call to SSL_read()/SSL_write() being issued after having already received a fatal error.
This issue was reported to OpenSSL by David Benjamin (Google).
- rsaz_1024_mul_avx2 overflow bug on x86_64 - There is an overflow bug in the AVX2 Montgomery multiplication procedure used in exponentiation with 1024-bit moduli. No EC algorithms are affected. Analysis suggests that attacks against RSA and DSA as a result of this defect would be very difficult to perform and are not believed likely. Attacks against DH1024 are considered just feasible, because most of the work necessary to deduce information about a private key may be performed offline. The amount of resources required for such an attack would be significant. However, for an attack on TLS to be meaningful, the server would have to share the DH1024 private key among multiple clients, which is no longer an option since CVE-2016-0701.
This only affects processors that support the AVX2 but not ADX extensions like Intel Haswell (4th generation).
This issue was reported to OpenSSL by David Benjamin (Google). The issue was originally found via the OSS-Fuzz project.