In June 2018, openssl.org released a security advisory detailing several security issues. The following vulnerabilities that may affect the TLS/SSL data-plane of ACOS devices reported in that advisory are addressed in this document.
|openssl: Malicious server can send large prime to client during DH(E) TLS handshake causing the client to hang
The table below indicates releases of ACOS exposed to these vulnerabilities and ACOS releases that address them. ACOS release families not indicated below are unaffected by these vulnerabilities.
Customers using affected ACOS releases can overcome vulnerability exposures by updating to the indicated resolved release. If the table does not list a corresponding resolved or unaffected release, then no ACOS release update is currently available.
Releases Resolved or Unaffected
4.1.4 – 4.1.4-P1
4.1.2 – 4.1.2-P4
4.1.1 – 4.1.1-P8
4.1.0 – 4.1.0-P11
2.7.2 – 2.7.2-P12
Workarounds and Mitigations
Exposure to this vulnerability can be fully mitigated by disabling DHE-based ciphers in configured ACOS ssl-server templates.
The following table shares brief descriptions of the vulnerabilities addressed in this document.
During key agreement in a TLS handshake using a DH(E) based ciphersuite a malicious server can send a very large prime value to the client. This will cause the client to spend an unreasonably long period of time generating a key for this prime resulting in a hang until the client has finished. This could be exploited in a Denial Of Service attack.
Due to the low severity of this issue we are not issuing a new release of OpenSSL 1.1.0 or 1.0.2 at this time. The fix will be included in OpenSSL 1.1.0i and OpenSSL 1.0.2p when they become available. The fix is also available in commit ea7abeeab (for 1.1.0) and commit 3984ef0b7 (for 1.0.2) in the OpenSSL git repository.
The following table shares brief descriptions for the vulnerabilities addressed in this document.
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