In a statement on Monday, the Canada Revenue Agency (CRA), Canada's tax-collection agency, confirmed that the Heartbleed vulnerability was to blame for the loss of tax-related information.
Last week, the CRA made headlines when they shutdown access to parts of its website, partly as a precaution, due to the concern created by the Heartbleed vulnerability. The main reason for the downtime however, was so the agency could properly apply and test the fix before re-enabling services to the public.
Unfortunately, during the patching process, the CRA discovered that the vulnerability had already been exploited, and someone managed to collect the Social Insurance Numbers (SIN) of approximately 900 people.
"Regrettably, the CRA has been notified by the Government of Canada's lead security agencies of a malicious breach of taxpayer data that occurred over a six-hour period," Andrew Treusch, Commissioner of the CRA, said in a statement.
"Based on our analysis to date, Social Insurance Numbers (SIN) of approximately 900 taxpayers were removed from CRA systems by someone exploiting the Heartbleed vulnerability. 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 Heartbleed flaw allows an attacker to retrieve data stored in the webserver's memory in 64kb chunks. Because there is no limit on the number of memory requests made, an attacker can repeatedly call for blocks of data.
Bypassing the assumed protection normally associated with SSL/TLS, the Heartbleed flaw gained instant attention, because it had the ability to expose critical information, such as usernames, passwords, source code, and more.
Organizations both large and small spent the days following the April 7 disclosure of Heartbleed in a rush, as they moved to patch vulnerable software.
NOTE: Additional information on Heartbleed (CVE-2014-0160), including an overview of the problem, and the steps needed to fix it, is here.
In his statement, Treusch said that the RCMP was investigating the incident, and that those impacted by the data breach would be contacted by mail. Each person impacted will also be given a dedicated 800 number to obtain additional information, as well as credit protection services.
In addition, the statement stressed that contact from the CRA about this incident will only come from registered mail.
"The Agency will not be calling or emailing individuals to inform them that they have been impacted we want to ensure that our communications are secure and cannot be exploited by fraudsters through phishing schemes."
"As the Commissioner of the CRA, I want to express regret to Canadians for this service interruption. In particular, I share the concern and dismay of those individuals whose privacy has been impacted by this malicious act." Treusch added.