Researchers examined 14 commonly used software programmes that claim to make computers safer by protecting data, blocking out viruses or shielding users from questionable content on the internet.
They found that these programmes were doing more harm than good.
"Out of the products we analysed, we found that all of them lower the level of security normally provided by current browsers, and often bring serious security vulnerabilities," said Xavier de Carne de Carnavalet from Concordia University in Canada.
At the root of the problem is how security applications act as gatekeepers, filtering dangerous or unwanted elements by inspecting secure web pages before they reach the browser, researchers said.
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Normally, browsers themselves have to check the certificate delivered by a website, and verify that it has been issued by a proper entity, called a Certification Authority (CA).
But security products make the computer "think" that they are themselves a fully entitled CA, thus allowing them to fool browsers into trusting any certificate issued by the products, researchers said.
"We reported our findings to the respective vendors so they can fix their products. Not all of them have responded yet, but we hope to bring their attention to these issues," said Mohammad Mannan from Concordia University.
"We also hope that our work will bring more awareness among users when choosing a security suite or software to protect their children's online activities," added de Carnavalet.
He cautioned that internet users should not view these security products as a panacea.
"Parental control apps exist that do not interfere with secure content, but merely block websites by their domain name, which is probably effective enough," he added.