Test Center guide to browser security
Chrome, Firefox, Internet Explorer, Opera, and Safari have different security advantages and shortcomings. More important than the browser you choose, however, is how you maintain and use it.Follow @rogeragrimes
How to measure the security of a browser
Vulnerability counts and the frequency of announced exploits account for much of the overall risk to a Web browser, but they are far from the only relevant factors to consider. In this security review, the following criteria were used during evaluation:
Security model. Each browser is coded on the underlying strength of the browser vendor's chosen security model. This model is what keeps the untrusted network side separated from the more trusted security zones. If malware is able to exploit the browser, how easily can it compromise the whole system? What defenses did the vendor include in the browser's underlying design to prevent malicious use? How is malicious redirection (such as cross-domain cross-site scripting and frame theft) prevented? Is memory secured and cleared against malicious reuse? Does the browser give end-users multiple security domains or zones with varying levels of functionality in which to place different Web sites according to their level of associated trust? What end-user protections have been built into the browser? Does the browser attempt to update itself? All of these questions, and more, go into determining the fitness of a browser's security model.
When the browser runs on Windows does it take advantage of Data Execution Prevention (DEP)? If it runs on Windows Vista, does it use file and registry virtualization, Mandatory Integrity Controls (see sidebar), or Address Space Layout Randomization? These topics require too much space to discuss appropriately in this review, but all four mechanisms can make it harder for malware to gain system control.
Feature set and complexity. More features and increased complexity are the antithesis of computer security. Additional features mean more code available to exploit with more unexpected interactions. Conversely, a browser with a minimal feature set may not be able to render popular Web sites, which forces the user to use another browser or to install potentially insecure add-ons. Popular add-ons are often exploited by malware writers.
User-definable security zones (also known as security domains) are also an important feature. Ultimately, less functionality translates into better security. Security zones provide a way to classify various Web sites as more trustworthy and, hence, suited for greater functionality. You should be able to trust your company's Web sites significantly more than a Web site offering pirated software or a small Web page served up by someone you don't know. Security zones allow you to set various security settings and functionalities based upon the Web site's location, domain, or IP address.
Security domains are used in every computer security product (firewalls, IPSes, and so on) to establish security boundaries and areas of default trust. Having a security zone in a browser extends that model. Browsers without security zones encourage you to treat all Web sites with the same level of trust -- as well as to reconfigure the browser or use another browser for less trustworthy Web sites before each visit.
Vulnerability announcements and attacks. How many vulnerabilities have been found and publicly announced against the browser product? Are the vulnerability counts going up or down as the vendor patches its browser? How severe have the vulnerabilities been? Do they allow full system compromise or denial of service? How many vulnerabilities are currently unpatched? What is the history of zero-day attacks against the vendor? How often is the vendor's browser targeted versus a competitor's product?