The Heartbleed OpenSSL vulnerability that has shocked the security industry has evolved beyond being merely a theoretically dangerous bug: two organizations have reportedly been victimized by attackers exploiting the flaw.
On its website, Mumsnet, a U.K.-based website for parents, said it first became aware of the Heartbleed bug on April 10, three days after it was made public, and immediately tested its servers for the vulnerability. Upon confirming that it was vulnerable, Mumsnet applied the patched version of OpenSSL, but even on April 11, attackers were spotted accessing data from its users' accounts.
Over the weekend, the site decided to force all of its users to reset their login credentials, though Mumsnet has yet to confirm that anyone exploiting Heartbleed was doing so for malicious purposes.
"It is possible that this information could then have been used to log in as you and give access to your posting history, your personal messages and your personal profile," said Mumsnet, "although we should say that we have seen no evidence of anyone's account being used for anything other than to flag up the security breach, thus far.
"We have no way of knowing which Mumsnetters were affected by this," continued Mumsnet. "The worst case scenario is that the data of every Mumsnet user account was accessed. That's why we've required every user to reset their password."
Separately, the Canada Revenue Agency (CRA), akin to the IRS in the U.S., said in a statement on its website that the Social Insurance Numbers of approximately 900 taxpayers were removed from its systems by someone exploiting Heartbleed. The exploit occurred despite the CRA's move to temporarily shut down its online tax-filing services last week shortly after learning of the OpenSSL vulnerability.
The Canadian tax agency relaunched its online service Sunday after working to apply the Heartbleed patch and test the security of its systems, but said the breach cleanup will continue.
"We are currently going through the painstaking process of analyzing other fragments of data, some that may relate to businesses, that were also removed.
The CRA is one of many organizations that was vulnerable to Heartbleed, despite our robust controls," said the CRA. "Thanks to the dedicated support of Shared Services Canada and our security partners, the Agency was able to contain the infiltration before the systems were restored yesterday. Further, analysis to date indicates no other CRA infiltrations have occurred either before or after this breach."
These Heartbleed exploits demonstrate the ability of attackers to glean sensitive information, but questions remain over one of the more serious aspects related to the bug: stealing private SSL keys.
CloudFlare, Akamai discover Heartbleed's complexity
A pair of security vendors have also discovered just how tricky and pervasive the Heartbleed flaw is, supporting the growing number of security experts who have said it is among the most widespread Internet bugs of all time.
In a blog post last week, San Francisco-based content delivery network CloudFlare Inc., which patched its OpenSSL implementations based on an early disclosure, attempted to pour cold water on theories that Heartbleed could have easily exposed private key data, particularly in the case of Nginx servers.
"After extensive testing on our software stack, we have been unable to successfully use Heartbleed on a vulnerable server to retrieve any private key data," said CloudFlare's Nick Sullivan.
To test its own findings, CloudFlare decided to run a challenge for the security community by setting up an Nginx server running a vulnerable version of OpenSSL, with the goal being to steal the private keys from the server. Around nine hours after the challenge launched, Russia-based software engineer Fedor Indutny was the first to succeed, but only after sending over 2.5 million heartbeat requests. Ilkka Mattila, a Finland-based information security advisor with NCSC-FI, accomplished the task shortly after Indutny and sent a relatively miniscule 100,000 requests.
Indutny has since published the extraction script he used to exploit the Heartbleed bug on his blog, noting that "it won't produce any result immediately." Despite the time-consuming nature of the exploit, CloudFlare has since said it is taking steps to replace the private SSL keys it manages for customers based on the challenge results.
"Our recommendation based on this finding is that everyone reissue and revoke their private keys," said CloudFlare.
Separately, Akamai Technologies Inc. over the weekend withdrew a patch it had issued to protect its customers from Heartbleed.
After realizing it was vulnerable last week, the Cambridge, Mass.-based vendor released a memory-allocation tool to prevent SSL keys from leaking out. However, in a blog post Sunday evening, Akamai chief security officer Andy Ellis said that a security researcher, Willem Pinckaers, contacted Akamai and reported a bug in its Heartbleed fix.
"As a result, we have begun the process of rotating all customer SSL keys/certificates," Ellis said. "Some of these certificates will quickly rotate; some require extra validation with the certificate authorities and may take longer."