Heartbleed encryption flaw leaves millions of sites at risk

A flaw in an encryption technology used to protect major websites including Yahoo has left a huge amount of private data at risk – and internet giants are scrambling to find fixes for a problem which could leave customer data exposed to criminals.

The Heartbleed encryption flaw is described as one of the “most serious security flaws ever found” according to the Telegraph’s report. It affects the open-source encryption software OpenSSL – which is used on millions of web servers – and has been undiscovered for more than two years. The Telegraph reports that it could have been used to steal passwords, credit card details and even encryption keys, without trace.

Major sites including Yahoo Mail and others, are vulnerable, and are scrambling to deploy fixes. A  proof-of-concept exploit for the encryption flaw has already been posted on coding site Github.

The researchers who discovered the Heartbleed encryption flaw say that it has left private keys, and other secrets exposed “for years”. The researchers tested the vulnerability themselves and wrote that they were able to gain access to large amounts of data, leaving no trace of their presence.

“We have tested some of our own services from an attacker’s perspective,” they wrote. “We attacked ourselves from outside, without leaving a trace. Without using any privileged information, we were able steal from ourselves secret keys, usernames and passwords, instant messages, emails and business critical documents and communication.”

The bug was discovered by researchers from Finnnish firm Codenomicon working with Google. A dedicated website helps to explain some of the risks – although the researchers admit they do not know how widely the bug has been exploited.

“The Heartbleed Bug is a serious vulnerability in the popular OpenSSL cryptographic software library. This weakness allows stealing the information protected, under normal conditions, by the SSL/TLS encryption used to secure the Internet,” the firm writes.

“The Heartbleed bug allows anyone on the Internet to read the memory of the systems protected by the vulnerable versions of the OpenSSL software. This compromises the secret keys used to identify the service providers and to encrypt the traffic, the names and passwords of the users and the actual content. This allows attackers to eavesdrop on communications, steal data directly from the services and users and to impersonate services and users.”

ESET Senior Research Fellow David Harley offers advice on how to deal with problem, “Sites that have never run the 1.0.1 and 1.0.2-beta releases of OpenSSL including 1.0.1f and 1.0.2-beta1 shouldn’t be panicking about this, but those that are running them need to upgrade to 1.0.1g or recompile -DOPENSSL_NO_HEARTBEATS, as recommended by the OpenSSL security advisory. However, they should also be looking for and revoking (and reissuing) compromised keys, and changing user passwords. This applies even to sites that ran a vulnerable version for a while but have upgraded since, as the bug has been around since 2011. While I haven’t checked all the links and resources listed there, this site looks like an excellent starting point for sites that need to know more about the problem and its remediation, as well as the heartbleed.com page. It’s worth remembering that some embedded devices also use OpenSSL: it isn’t just a server issue.”

Open SSL wrote on their site, “A missing bounds check in the handling of the TLS heartbeat extension can be used to reveal up to 64kB of memory to a connected client or server. This issue did not affect versions of OpenSSL prior to 1.0.1.”

Author , We Live Security

  • Heartbleed isn’t an encryption flaw. Heartbleed refers to a bug in OpenSSL 1.0.1 through 1.0.1f that doesn’t perform bounds-checking on TLS and DTLS heartbeat responses, which allows an attacker to read up to 64 KB of memory from the target server. The encryption isn’t the flawed part here.

    • I think Rob meant that it’s a flaw in encryption technology, but you’re right of course.

    • Simon

      So is like a buffer underflow? Sending less than expected but recalling the allowed length?

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