The Same Origin Policy is "one of the fundamental security mechanisms that makes the internet safe to use," Ormandy said. "With the Same Origin Policy defeated, a malicious website can interact with your Mail, Intranet Systems, Registrar, Banks and Payroll systems, and so on."
Ormandy's comments throughout the paper suggest that many of these vulnerabilities should have been caught during the product development and quality assurance processes.
The researcher shared his findings with Sophos in advance and the company released security fixes for the vulnerabilities disclosed in the paper. Some of the fixes were rolled out on Oct. 22, while the others were released on Nov. 5, the company said Monday in a blog post.
There are still some potentially exploitable issues discovered by Ormandy through fuzzing -- a security testing method -- that were shared with Sophos, but weren't publicly disclosed. Those issues are being examined and fixes for them will start to be rolled out on Nov. 28, the company said.
"As a security company, keeping customers safe is Sophos's primary responsibility," Sophos said. "As a result, Sophos experts investigate all vulnerability reports and implement the best course of action in the tightest time period possible."
"It's good that Sophos has been able to deliver the suite of fixes within weeks, and without disrupting customers' usual operations," Graham Cluley, a senior technology consultant at Sophos, said Tuesday via email. "We are grateful that Tavis Ormandy found the vulnerabilities, as this has helped make Sophos's products better."
However, Ormandy wasn't satisfied with the time it took Sophos to patch the critical vulnerabilities he reported. The issues were reported to the company on September 10, he said.
"In response to early access to this report, Sophos did allocate some resources to resolve the issues discussed, however they were clearly ill-equipped to handle the output of one co-operative, non-adversarial security researcher," Ormandy said. "A sophisticated state-sponsored or highly motivated attacker could devastate the entire Sophos user base with ease."
"Sophos claim their products are deployed throughout healthcare, government, finance and even the military," the researcher said. "The chaos a motivated attacker could cause to these systems is a realistic global threat. For this reason, Sophos products should only ever be considered for low-value non-critical systems and never deployed on networks or environments where a complete compromise by adversaries would be inconvenient."
Ormandy's paper contains a section that describes best practices and includes the researcher's recommendations for Sophos customers, like implementing contingency plans that would allow them to disable Sophos antivirus installations on short notice.
"Sophos simply cannot react fast enough to prevent attacks, even when presented with a working exploit," he said. "Should an attacker choose to use Sophos Antivirus as their conduit into your network, Sophos will simply not be able to prevent their continued intrusion for some time, and you must implement contingency plans to handle this scenario if you choose to continue deploying Sophos."