A few days ago, Google identified a vulnerability in the design of SSL 3.0. This vulnerability allows the plaintext of secure connections to be calculated by a network attacker. This issue was discovered by Bodo Moller in collaboration with Thai Duong and Krzysztof Kotowicz (also Googlers). The attack has been named as the POODLE bites attack, standing for Padding Oracle On Downgraded Legacy Encryption. Check out the document available on the OpenSSL website to learn more about this vulnerability.
What is POODLE?
To maintain compatibility with legacy servers, many TLS clients implement a downgrade dance: in a first handshake attempt, offer the highest protocol version supported by the client; if this handshake fails, they retry (possibly repeatedly) with earlier protocol versions. Unlike proper protocol version negotiation (if the client offers TLS 1.2, the server may respond with, say, TLS 1.0), this downgrade can also be triggered by network glitches, or by active attackers. So if an attacker that controls the network between the client and the server interferes with any attempted handshake offering TLS 1.0 or later, such clients will readily confine themselves to SSL 3.0.
Encryption in SSL 3.0 uses either the RC4 stream cipher or a block cipher in CBC mode. RC4 is well known to have biases, meaning that if the same secret (such as a password or HTTP cookie) is sent over many connections and thus encrypted with many RC4 streams, more and more information about it will leak.
Unlike with the BEAST and Lucky 13 attacks, there is no reasonable workaround. This leaves us with no secure SSL 3.0 cipher suites at all: to achieve secure encryption, SSL 3.0 must be avoided entirely.
Does POODLE have an impact on cloud environments?
Any system using SSL 3.0 might fall under this attack. Right now, all the Cloud service providers are acting on this vulnerability and updated their customers to close the doors towards the attack.
Amazon AWS Cloud has two public facing services called Elastic Load Balancer (ELB) and CloudFront, both using the SSLV3 protocol to serve the requests via the secured channel. Generally, the customers themselves will manage the SSL configurations in these two services. To mitigate the POODLE attacks on these two services, we have to disable the SSLV3 Support.
Disable the SSLV3 Protocol to handle POODLE on Amazon AWS ELB
All the ELBs which are created after 10/14/2014 5:00 PM PDT will use a new SSL Negotiation Policy that will by default no longer enable SSLv3.
For the existing ELBs, it’s necessary to manually disable SSLv3 via the AWS Management console:
- Select your load balancer (EC2 -> Load Balancers) in the appropriate region
- In the Listeners tab, click “Change” in the Cipher column.|
- Ensure that the radio button for “Predefined Security Policy” is selected, in the dropdown select the “ELBSecurityPolicy-2014-10” policy. You can see the Protocol-SSLV3 is unchecked after selecting the policy.
- Click “Save” to apply the settings to the listener
- Repeat these steps for each listener that is using HTTPS or SSL for each LoadBalancer.
If you require the SSLv3 support you can re-enable it by selecting the “ELBSecurityPolicy-2014-10” Policy or manually configure the SSL ciphers and protocols as per your requirements. Nevertheless, this will expose you again to POODLE, so you should consider this opportunity very carefully
Disable the SSLv3 Protocol to handle POODLE attacks on Cloud Front
Similarly to Amazon ELB, Amazon AWS has taken care of the issue disabling SSLv3 for the customers who use the default SSL settings. Nevertheless, customers who are using custom SSL certificates with Amazon Cloud Front should disable the SSLv3 protocol manually by following the steps below in the Amazon CloudFront Management Console:
- Select your distribution, then click “Distribution Settings”.
- Click the “Edit” button on the “General” tab.
- In the “Custom SSL Client Support” section, select the option that says: “Only Clients that Support Server Name Indication (SNI)”.
- Click “Yes, Edit” to save these revised settings.
AWS API endpoints are not affected by the attack described in the POODLE paper. Instead of using cookies to authenticate users, a unique signature is computed for every request. No action is required from customers that use the AWS SDK or other SDKs to access our API endpoints.
AWS Security: Bastion Host, NAT instances and VPC Peering
Effective security requires close control over your data and resources. Bastion hosts, NAT instances, and VPC peering can help you secure your AWS infrastructure. Welcome to part four of my AWS Security overview. In part three, we looked at network security at the subnet level. This ti...
Top 13 Amazon Virtual Private Cloud (VPC) Best Practices
Amazon Virtual Private Cloud (VPC) brings a host of advantages to the table, including static private IP addresses, Elastic Network Interfaces, secure bastion host setup, DHCP options, Advanced Network Access Control, predictable internal IP ranges, VPN connectivity, movement of interna...
Big Changes to the AWS Certification Exams
With AWS re:Invent 2019 just around the corner, we can expect some early announcements to trickle through with upcoming features and services. However, AWS has just announced some big changes to their certification exams. So what’s changing and what’s new? There is a brand NEW ...
New on Cloud Academy: ITIL® 4, Microsoft 365 Tenant, Jenkins, TOGAF® 9.1, and more
At Cloud Academy, we're always striving to make improvements to our training platform. Based on your feedback, we released some new features to help make it easier for you to continue studying. These new features allow you to: Remove content from “Continue Studying” section Disc...
AWS Security Groups: Instance Level Security
Instance security requires that you fully understand AWS security groups, along with patching responsibility, key pairs, and various tenancy options. As a precursor to this post, you should have a thorough understanding of the AWS Shared Responsibility Model before moving onto discussi...
Cloud Migration Risks & Benefits
If you’re like most businesses, you already have at least one workload running in the cloud. However, that doesn’t mean that cloud migration is right for everyone. While cloud environments are generally scalable, reliable, and highly available, those won’t be the only considerations dri...
Real-Time Application Monitoring with Amazon Kinesis
Amazon Kinesis is a real-time data streaming service that makes it easy to collect, process, and analyze data so you can get quick insights and react as fast as possible to new information. With Amazon Kinesis you can ingest real-time data such as application logs, website clickstre...
Google Cloud Functions vs. AWS Lambda: The Fight for Serverless Cloud Domination
Serverless computing: What is it and why is it important? A quick background The general concept of serverless computing was introduced to the market by Amazon Web Services (AWS) around 2014 with the release of AWS Lambda. As we know, cloud computing has made it possible for users to ...
Google Vision vs. Amazon Rekognition: A Vendor-Neutral Comparison
Google Cloud Vision and Amazon Rekognition offer a broad spectrum of solutions, some of which are comparable in terms of functional details, quality, performance, and costs. This post is a fact-based comparative analysis on Google Vision vs. Amazon Rekognition and will focus on the tech...
New on Cloud Academy: CISSP, AWS, Azure, & DevOps Labs, Python for Beginners, and more…
As Hurricane Dorian intensifies, it looks like Floridians across the entire state might have to hunker down for another big one. If you've gone through a hurricane, you know that preparing for one is no joke. You'll need a survival kit with plenty of water, flashlights, batteries, and n...
Amazon Route 53: Why You Should Consider DNS Migration
What Amazon Route 53 brings to the DNS table Amazon Route 53 is a highly available and scalable Domain Name System (DNS) service offered by AWS. It is named by the TCP or UDP port 53, which is where DNS server requests are addressed. Like any DNS service, Route 53 handles domain regist...
How to Unlock Complimentary Access to Cloud Academy
Are you looking to get trained or certified on AWS, Azure, Google Cloud Platform, DevOps, Cloud Security, Python, Java, or another technical skill? Then you'll want to mark your calendars for August 23, 2019. Starting Friday at 12:00 a.m. PDT (3:00 a.m. EDT), Cloud Academy is offering c...