Amazon tricks up CloudFront encryption with anti-spy feature

Spies and hackers will find it harder to unseal encrypted communications if they’ve already captured packets sent across Amazon’s content distribution network, CloudFront.

Amazon on Wednesday enabled ‘perfect forward secrecy’ (PFS) for customers that use its content distribution network (CDN), CloudFront, to speed up their apps. By switching on PFS, AWS will improve the effectiveness of secure sockets layer (SSL) encryption.

“This feature creates a new private key for each SSL session. In the event that a private key for a session was discovered, it could be used only to decode that session and no other, past or future,” Amazon Web Services (AWS) explained.

Like other CDNs, such as Akamai and CloudFlare, AWS CloudFront offers developers who host apps on Amazon’s infrastructure a way to speed up their apps across different regions by moving content to nodes that are closer to the end-user to cut out sluggish performance of an app from the user’s side.

Amazon’s Australian customers gained another CloudFront node in Melbourne this July, adding to its Sydney one. But until Wednesday, despite having SSL encryption enabled, they could have been more exposed than necessary to attacks that used the OpenSSL vulnerability Heartbleed to spill their private encryption key. 

PFS prevents “retroactive decryption”, where an attacker has gained access to an encrypted message that they cannot unseal today but could, in future — if they gained access to the private key — unseal those captured messages.

The issue that PFS deals with is the use of the same key across multiple SSL sessions. So, in the future, if a law enforcement agency has captured several encrypted sessions and then ordered a web company to hand over the key, they could unlock all historical messages protected by the same key. Since PFS creates a new key for each session, an attacker that acquires a key is limited to a single session. Essentially, it raises the cost of an attacker intent on unsealing encrypted sessions.   

One scenario PFS would have helped AWS CloudFront was when the OpenSSL Heartbleed memory leakage flaw was disclosed. CloudFront, along with Elastic Load Balancing, EC2, OpsWorks and Elastic Beanstalk were impacted by the bug.

As Electronic Frontiers Foundation noted at the time, certain Heartbleed attacks could force a server to cough up private encryption keys used to protect HTTPS traffic. Since EFF had PFS enabled, an attacker that stole EFF’s private SSL key today could not unseal encrypted traffic to its site from the past.

Read more: The week in security: Apple security scrutinised; certifications to boost cloud appeal

CloudFront would no longer be vulnerable if a similar flaw is found in future.

Another improvement to CloudFront includes SSL Session Tickets to smooth out the the SSL handshake process.

“After the negotiation is complete, the SSL server creates an encrypted session ticket and returns it to the client. Later, the client can present this ticket to the server as an alternative to a full negotiation when resuming or restarting a connection. The ticket reminds the server of what they have already agreed to as part of an earlier SSL handshake.”

AWS details further security enhancements here.

Read more: How to uncover the hidden threats in encrypted traffic


Follow @LiamT

Follow @CSO_Australia and sign up to the CSO Australia newsletter.

Join the CSO newsletter!

Error: Please check your email address.

Tags CloudFront encryptionamazonakamaisecurity‘perfect forward secrecy’ (PFS)CloudFlareanti-spye featureSSL encryption

More about Amazon Web ServicesAWSCSOEFF

Show Comments

Featured Whitepapers

Editor's Recommendations

Solution Centres

Stories by Liam Tung

Latest Videos

  • 150x50

    CSO Webinar: The Human Factor - Your people are your biggest security weakness

    ​Speakers: David Lacey, Researcher and former CISO Royal Mail David Turner - Global Risk Management Expert Mark Guntrip - Group Manager, Email Protection, Proofpoint

    Play Video

  • 150x50

    CSO Webinar: Current ransomware defences are failing – but machine learning can drive a more proactive solution

    Speakers • Ty Miller, Director, Threat Intelligence • Mark Gregory, Leader, Network Engineering Research Group, RMIT • Jeff Lanza, Retired FBI Agent (USA) • Andy Solterbeck, VP Asia Pacific, Cylance • David Braue, CSO MC/Moderator What to expect: ​Hear from industry experts on the local and global ransomware threat landscape. Explore a new approach to dealing with ransomware using machine-learning techniques and by thinking about the problem in a fundamentally different way. Apply techniques for gathering insight into ransomware behaviour and find out what elements must go into a truly effective ransomware defence. Get a first-hand look at how ransomware actually works in practice, and how machine-learning techniques can pick up on its activities long before your employees do.

    Play Video

  • 150x50

    CSO Webinar: Get real about metadata to avoid a false sense of security

    Speakers: • Anthony Caruana – CSO MC and moderator • Ian Farquhar, Worldwide Virtual Security Team Lead, Gigamon • John Lindsay, Former CTO, iiNet • Skeeve Stevens, Futurist, Future Sumo • David Vaile - Vice chair of APF, Co-Convenor of the Cyberspace Law And Policy Community, UNSW Law Faculty This webinar covers: - A 101 on metadata - what it is and how to use it - Insight into a typical attack, what happens and what we would find when looking into the metadata - How to collect metadata, use this to detect attacks and get greater insight into how you can use this to protect your organisation - Learn how much raw data and metadata to retain and how long for - Get a reality check on how you're using your metadata and if this is enough to secure your organisation

    Play Video

  • 150x50

    CSO Webinar: How banking trojans work and how you can stop them

    CSO Webinar: How banking trojans work and how you can stop them Featuring: • John Baird, Director of Global Technology Production, Deutsche Bank • Samantha Macleod, GM Cyber Security, ME Bank • Sherrod DeGrippo, Director of Emerging Threats, Proofpoint (USA)

    Play Video

  • 150x50

    IDG Live Webinar:The right collaboration strategy will help your business take flight

    Speakers - Mike Harris, Engineering Services Manager, Jetstar - Christopher Johnson, IT Director APAC, 20th Century Fox - Brent Maxwell, Director of Information Systems, THE ICONIC - IDG MC/Moderator Anthony Caruana

    Play Video

More videos

Blog Posts