Dark Reading is part of the Informa Tech Division of Informa PLC

This site is operated by a business or businesses owned by Informa PLC and all copyright resides with them.Informa PLC's registered office is 5 Howick Place, London SW1P 1WG. Registered in England and Wales. Number 8860726.

Attacks/Breaches

3/1/2016
10:50 PM
Connect Directly
Twitter
RSS
E-Mail
50%
50%

SSL ‘DROWNs’ In Yet Another Serious Security Flaw

Millions of SSL servers vulnerable to newly discovered attack that breaks encryption and exposes communication and information in Web and email servers and VPNs.

It’s déjà vu all over again: millions of SSL servers worldwide are at risk as a newly discovered dangerous attack exploits a long-retired yet still available version of the Secure Sockets Layer protocol.

The 1990s-era SSLv2, which long ago was deemed obsolete and since has been dropped by the major browser vendors, still lives in many servers, either in default or active mode, due to misconfiguration, neglect, or older embedded devices. The so-called DROWN (Decrypting RSA with Obsolete and Weakened eNcryption) attack exploits that oversight and resurrects SSLv2 to break encrypted communications and steal sensitive information from Web and email servers or via VPN sessions, an international team of researchers -- from Tel Aviv University, Münster University of Applied Sciences, Horst Görtz Institute for IT security, Ruhr University Bochum, University of Pennsylvania, Hashcat Project, University of Michigan, Two Sigma/OpenSSL, and Google/OpenSSL -- has found.

DROWN also can decrypt past encrypted sessions that were recorded. Even client machines that don’t use SSLv2 are vulnerable if the server they communicate with supports the older protocol.

Some 33% of all HTTPS servers, including 25% of the top one million HTTPS domains and 22% of all browser-trusted sites, are vulnerable to DROWN attacks, according to data provided by the researchers who found the flaw. Other estimates are even higher, from six- to 11 million servers worldwide affected.

OpenSSL today issued an update to address DROWN as well as other vulnerabilities in its open-source software, which is used in many SSL implementations. The update disables SSLv2 default settings as well as weak ciphers in SSLv3 and above in default settings of OpenSSL.

“DROWN is a classic example of a 'cross protocol attack,'" Matthew Green, a cryptographer and professor at Johns Hopkins University, wrote in a blog post today. "This type of attack makes use of bugs in one protocol implementation (SSLv2) to attack the security of connections made under a different protocol entirely -- in this case, TLS."

Encryption expert Bruce Schneier says the underlying problem highlighted by DROWN is the traditional struggle between security updates and backwards-compatibility. “The whole point of security updates is not ... backwards compatibility. But everyone wants backwards compatibility, so we’re caught in that again and again,” Schneier said in an interview with Dark Reading.

Cheap But Not Easy

The researchers found that even when OpenSSL’s default setting for SSLv2 is in place, client systems can request SSLv2’s weaker encryption option. An attacker can use DROWN against any TLS (the updated and more airtight version of SSL encryption) protocol that is using the same RSA server key, so even systems that aren’t supporting SSLv2 are vulnerable.

“The attack is not trivial, but can be done cheaply against high-value targets,” says Ivan Ristic, director of engineering at Qualys, and an SSL expert. Ristic, who posted a detailed blog today about the attack, has this blunt recommendation: “Disable SSLv2 on all servers you have. It’s as simple as that.”

The attack costs only about $440 using Amazon EC2 cloud computing resources, and takes just eight hours to pull off, Ristic says.

DROWN is not as critical as Heartbleed, however, security experts say. Nor is it especially devastating: “This is not apocalyptic,” says Dan Kaminsky, chief security officer at WhiteOps. But it’s a “practical attack” backed up by the demonstrated attack the researchers executed, Kaminsky says.

A server is vulnerable to the DROWN attack if it allows SSLv2 connections, or if the server’s private key is used on any other server that supports SSLv2 connections. “Many companies reuse the same certificate and key on their web and email servers, for instance. In this case, if the email server supports SSLv2 and the web server does not, an attacker can take advantage of the email server to break TLS connections to the web server,” according to the DROWN team’s website post, which also includes instructions for disabling SSLv2 in different types of servers. 

The team has published a technical paper on DROWN as well.

OpenSSL 1.0.2g updates 1.0.2, and OpenSSl 1.0.1s updates 1.0.1. 

“Once again, we realise that obsolete crypto is dangerous. For many years the argument for not disabling SSL v2 was that there was no harm because no browsers used it anyway,” Qualys’ Ristic wrote in his post. “...in the future we must ensure that all obsolete crypto is aggressively removed from all systems. If it's not, it's going to come back to bite us, sooner or later.”

DROWN highlights the challenges of getting security engineering, software security, and encryption right, says Gary McGraw, CTO of Cigital. "Security engineering is very hard, software security is very hard, and cryptography is very hard," McGraw says.

 

Interop 2016 Las VegasFind out more about security threats at Interop 2016, May 2-6, at the Mandalay Bay Convention Center, Las Vegas. Register today and receive an early bird discount of $200.

Kelly Jackson Higgins is the Executive Editor of Dark Reading. She is an award-winning veteran technology and business journalist with more than two decades of experience in reporting and editing for various publications, including Network Computing, Secure Enterprise ... View Full Bio
 

Recommended Reading:

Comment  | 
Print  | 
More Insights
Comments
Oldest First  |  Newest First  |  Threaded View
RyanSepe
50%
50%
RyanSepe,
User Rank: Ninja
3/2/2016 | 8:09:22 AM
Vulnerability Results
Time to break out the old heartbleed results to see which servers had open ssl on them. I hope other outlets describing DROWN stress that its not as critical as heartbleed otherwise there is going to be another panic driven scramble on our hands.
Commentary
Ransomware Is Not the Problem
Adam Shostack, Consultant, Entrepreneur, Technologist, Game Designer,  6/9/2021
Edge-DRsplash-11-edge-ask-the-experts
How Can I Test the Security of My Home-Office Employees' Routers?
John Bock, Senior Research Scientist,  6/7/2021
News
New Ransomware Group Claiming Connection to REvil Gang Surfaces
Jai Vijayan, Contributing Writer,  6/10/2021
Register for Dark Reading Newsletters
White Papers
Video
Cartoon Contest
Write a Caption, Win an Amazon Gift Card! Click Here
Latest Comment: Google's new See No Evil policy......
Current Issue
The State of Cybersecurity Incident Response
In this report learn how enterprises are building their incident response teams and processes, how they research potential compromises, how they respond to new breaches, and what tools and processes they use to remediate problems and improve their cyber defenses for the future.
Flash Poll
How Enterprises are Developing Secure Applications
How Enterprises are Developing Secure Applications
Recent breaches of third-party apps are driving many organizations to think harder about the security of their off-the-shelf software as they continue to move left in secure software development practices.
Twitter Feed
Dark Reading - Bug Report
Bug Report
Enterprise Vulnerabilities
From DHS/US-CERT's National Vulnerability Database
CVE-2021-24368
PUBLISHED: 2021-06-20
The Quiz And Survey Master – Best Quiz, Exam and Survey Plugin WordPress plugin before 7.1.18 did not sanitise or escape its result_id parameter when displaying an existing quiz result page, leading to a reflected Cross-Site Scripting issue. This c...
CVE-2021-31664
PUBLISHED: 2021-06-18
RIOT-OS 2021.01 before commit 44741ff99f7a71df45420635b238b9c22093647a contains a buffer overflow which could allow attackers to obtain sensitive information.
CVE-2021-33185
PUBLISHED: 2021-06-18
SerenityOS contains a buffer overflow in the set_range test in TestBitmap which could allow attackers to obtain sensitive information.
CVE-2021-33186
PUBLISHED: 2021-06-18
SerenityOS in test-crypto.cpp contains a stack buffer overflow which could allow attackers to obtain sensitive information.
CVE-2021-31272
PUBLISHED: 2021-06-18
SerenityOS before commit 3844e8569689dd476064a0759d704bc64fb3ca2c contains a directory traversal vulnerability in tar/unzip that may lead to command execution or privilege escalation.