CSRF vulnerability at CloudAtCost.com

CloudAtCost.com provides low-cost virtual machines hosted in Canada. panel.cloudatcost.com is the management interface, where customers can install OS images, access a console, etc.

A cross-site request forgery (CSRF) vulnerability was discovered in this web application. If a customer could be tricked into visiting a crafted URL while logged in, an attacker could change the victim’s password, gaining access to the management interface.

In turn, this grants root access on all the victim’s VMs, the ability to wipe or reinstall VMs, and potentially allows the attacker to spend the victim’s money on CloudAtCost products and services.

Changing the password does not end the session or email the user, so the victim will not immediately notice anything is wrong. Exploitation of CSRF is difficult to detect on the server, so CloudAtCost is unlikely to notice anything is wrong either.

There is no evidence the vulnerability is being exploited, but exploitation is trivial and the impact of exploitation is severe. Exploitation is simple: build a URL of the following form:


Any method which gets the victim to load the crafted URL in their browser while logged in will cause their password to be changed, and the attacker can simply log in. Phishing emails are a common exploitation vector. A watering hole attack could also work: create a website that cloudatcost users would visit, or use one which already exists (such as https://forum.cloudatcost.com) and embed the crafted URL as an img resource, for example, and the attacker would achieve a similar effect. Other exploitation methods are certainly available, and practicable.


  • September 25, 2014: vulnerability discovered, and disclosed to CloudAtCost through a customer support ticket. Feedback is passed along, and the customer support ticket is closed.
  • September 25: vulnerability report is escalated via email. No reply.
  • October 2: vulnerability report is escalated via email, and a single point of contact at CloudAtCost is provided. Details are provided to that contact directly. No reply.
  • October 9: Direct contact is made with CloudAtCost and the Canadian Cyber Incident Response Centre (CCIRC), and full details are repeated. Follow-up is promised, but doesn’t happen.
  • October 14: CCIRC reports that the vulnerability has been fixed. Testing shows that this is not the case. Clarification is requested from CloudAtCost. Deployment of the patch is scheduled for Nov 1.
  • November 3: The self-imposed date for deploying the patch (November 1) passes, and the application is still vulnerable. Clarification is requested from CloudAtCost. None is provided.
  • November 7: Information on the progress of deploying the patched application is requested. None is provided.
  • November 14: I spoke with a CloudAtCost representative on the phone, who said their team was having trouble getting a release out, and needed more time.
  • November 26: Information on the progress on deploying a fixed version of the web application was requested. No reply.
  • December 10: A hard deadline for public disclosure was set, and sent to CloudAtCost. The web application had been deployed in the past 3-4 days.
  • December 11: This disclosure is published.