How to defend against the OpenSSL Heartbleed flaw

CSOs need to take a number of steps as soon as possible to protect their organizations against the OpenSSL vulnerability that has shaken the tech industry, experts say.

[Vendors and administrators scramble to patch OpenSSL vulnerability]

The flaw, dubbed Heartbleed, makes it possible for an attacker to read a Web server's memory, which typically includes the private key that the protocol uses to encrypt traffic between the server and a browser.

The vulnerability, introduced into OpenSSL in 2011, affects all versions of the open-source implementation of the Secure Socket Layer (SSL) and Transport Layer Security (TLS) protocols. OpenSSL is widely used in Web servers, such as the popular open-source Apache, and in cloud services.

"CSOs should assume that they've been compromised," W. Hord Tipton, executive director of the International Information Systems Security Certification Consortium, or (ISC)2, said.

Among the first chores facing CSOs is identifying and prioritizing affected systems within the organization, patching those deemed most critical immediately, experts said. Of course, those systems open to the public Internet carry the greatest risk.

Fortunately, the OpenSSL Project, the stewards of the protocol, have released a patch, so security pros can get started right away in deploying the fix.

The next step would be to change the SSL certificates used by the servers, since there is no way of knowing whether they have been compromised. An attacker exploiting the flaw can do so without leaving a trace.

"If an attacker has the private key for SSL, they can decrypt any sort of communications that may have been archived in the past and any future communications using that same public/private certificate," said Michael Coates, product director for Shape Security and chairman of the Open Web Application Security Project (OWASP).

Once certificates have been changed, the next step is to have people who use the affected systems change their passwords.

"It's definitely prudent to evaluate the risk posture of the organization and decide whether you want to force a password rotation for your user base," Coates said.

CSOs should also increase monitoring for account takeover, fraud and abuse of systems. "We're definitely at a heightened state (of security)," Coates said.

To mitigate damage from future protocol-related vulnerabilities, experts recommend the use of perfect forward secrecy, a property for key-agreement protocols between a browser and server. PFS prevents a compromised private key from being used to decrypt pass communications.

Besides the affected systems within the organization, CSOs also have to evaluate the risk posed by Web sites that employees access everyday as part of their jobs. The first step is to create a catalog of these sites and contact the operators to find out where they stand in patching the OpenSSL flaw.

In some cases, CSOs could find it necessary to have employees not use the affected sites until they are patched.

"For the most sensitive systems, CSOs should consider having their personnel and executives take a one- or two-day hiatus, if they know when the relevant sites will be patched, new digital certificates re-issued, and new authentication credentials put into place," said Joram Borenstein, vice president of marketing at NICE Actimize, which specializes in security for the financial industry.

CSOs should also review their service level agreements with websites and software-as-a-service providers.

[What you need to know about Heartbleed and OpenSSL]

"They should be able to leverage security requirements within those contracts to push for a faster turnaround," Lucas Zaichkowsky, enterprise defense architect for computer forensics vendor AccessData, said. "If it's found that important contracts are lacking security requirements, make it a point to get them added now while there's a sense of urgency to support the initiative."

This story, "How to defend against the OpenSSL Heartbleed flaw" was originally published by CSO.

Copyright © 2014 IDG Communications, Inc.

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