CVE-2015-0285: Medium severity openssl vulnerability
The ssl3clienthello function in s3clnt.c in OpenSSL 1.0.2 before 1.0.2a does not ensure that the PRNG is seeded before proceeding with a handshake, which makes it easier for remote attackers to defeat cryptographic protection mechanisms by sniffing the network and then conducting a brute-force attack.
Other sources
Under certain conditions an OpenSSL 1.0.2 client can complete a handshake with an unseeded PRNG. The conditions are:
- The client is on a platform where the PRNG has not been seeded automatically, and the user has not seeded manually
- A protocol specific client method version has been used (i.e. not SSLclientmethodv23)
- A ciphersuite is used that does not require additional random data from the PRNG beyond the initial ClientHello client random (e.g. PSK-RC4-SHA).
If the handshake succeeds then the client random that has been used will have been generated from a PRNG with insufficient entropy and therefore the output may be predictable.
For example using the following command with an unseeded openssl will succeed on an unpatched platform:
openssl sclient -psk 1a2b3c4d -tls12 -cipher PSK-RC4-SHA
This issue affects OpenSSL version 1.0.2, and is fixed in version 1.0.2a.
Upstream patch:
https://git.openssl.org/gitweb/?p=openssl.git;a=commit;h=e1b568dd2462f7cacf98f3d117936c34e2849a6b
Acknowledgements:
Red Hat would like to thank the OpenSSL project for reporting this issue. Upstream acknowledges Matt Caswell of the OpenSSL development team as the original reporter.
— Red Hat
Affected Software
Remediation
Event History
Frequently Asked Questions
What is the severity of CVE-2015-0285?
CVE-2015-0285 is considered a high-severity vulnerability due to the potential exposure of sensitive data through insufficient PRNG seeding.
How do I fix CVE-2015-0285?
To fix CVE-2015-0285, you should upgrade OpenSSL to version 1.0.2a or later.
What impact does CVE-2015-0285 have on my system?
CVE-2015-0285 may allow attackers to conduct brute-force attacks on encrypted communications due to weak randomness in cryptographic operations.
Who is affected by CVE-2015-0285?
CVE-2015-0285 affects users of OpenSSL versions 1.0.2 and earlier, as well as beta releases of 1.0.2.
Is CVE-2015-0285 exploitable remotely?
Yes, CVE-2015-0285 can be exploited remotely by attackers if the vulnerable OpenSSL version is used in network applications.