The LogJam attack vulnerability – what you need to know


Logjam attack, a vulnerability that affects a number of major protocols has been discovered. The bug relates to a weakness within a cryptographic algorithm that is used in most protocols (such as HTTPS, SSH, IPsec, SMTPS, etc.) it is possible for a Man-in-The-Middle (MiTM) attacker to read and modify any data passed over the affected encrypted communication.


A large number of systems are open to this vulnerability, however as the bug was responsibly disclosed to all the appropriate vendors, patches have been developed or are scheduled for release. In the meantime, Sysnet would like to ensure that there is no need for panic and in order to simplify things we are going to provide you with a couple of suggestions.


For the simple user who needs to update the web browser:
Even though at the moment all modern web browsers are affected by this vulnerability updated releases have been scheduled. Even though at the moment all modern web browsers are affected by this vulnerability updated releases have been scheduled.


The only thing to do is to frequently check (daily) for any browser updates and consider this another opportunity to stop supporting old web browser versions. If you would like some more help with checking and updating your browser, click here and follow this simple guide.


For IT departments who maintain Web Server and/or Mail Servers
It is strongly suggested to update any web and/or mail server that you might have with the latest patches especially the ones that will be released in the following days to address this particular vulnerability (check daily). 


If your web and/or mail servers are managed by a third party, consider requesting them to disable the support for the export cipher suites and generate a unique 2048-bit Diffie-Hellman group. Most probably, they will know about this issue and they will do this already without any actions from your side.


For System Administrator and in-house Development teams
In case you have System administrators and in-house developers it is strongly suggested to ask them to review all the TLS libraries being used in production systems, in order to ensure these are up-to-date and do not accept Diffie-Hellman Groups smaller than 1024-bit. The only thing you need to do is to point them to the right direction by giving them our advisory.


For more technical details regarding this vulnerability and its nature, you may read our brief and comprehensive advisory here.


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