Introduction to Browser Security

Browser security is the application of Internet security to web browsers in order to protect networked data and computer systems from breaches of privacy or malware. Security exploits of browsers often use JavaScript — sometimes with cross-site scripting (XSS) — sometimes with a secondary payload using Adobe Flash. Security exploits can also take advantage of vulnerabilities (security holes) that are commonly exploited in all browsers (including Mozilla Firefox, Google Chrome, Opera, Microsoft Internet Explorer and Safari.

Web browsers can be breached in one or more of the following ways:

  • Operating system is breached and malware is reading/modifying the browser memory space in privilege mode.
  • Operating system has a malware running as a background process, which is reading/modifying the browser memory space in privileged mode
  • Main browser executable can be hacked
  • Browser components may be hacked
  • Browser plugins can be hacked
  • Browser network communications could be intercepted outside the machine

The browser may not be aware of any of the breaches above and may show user a safe connection is made.

Whenever a browser communicates with a website, the website, as part of that communication, collects some information about the browser (in order to process the formatting of the page to be delivered, if nothing else). If malicious code has been inserted into the website’s content, or in a worst-case scenario, if that website has been specifically designed to host malicious code, then vulnerabilities specific to a particular browser can allow this malicious code to run processes within the browser application in unintended ways (and remember, one of the bits of information that a website collects from a browser communication is the browser’s identity- allowing specific vulnerabilities to be exploited).

Once an attacker is able to run processes on the visitor’s machine, then exploiting known security vulnerabilities can allow the attacker to gain privileged access (if the browser isn’t already running with privileged access) to the “infected” system in order to perform an even greater variety of malicious processes and activities on the machine or even the victim’s whole network.

Breaches of web browser security are usually for the purpose of bypassing protections to display pop-up advertising collecting personally identifiable information (PII) for either Internet marketing or identity theft, website tracking or web analytics about a user against their will using tools such as web bugs, Clickjacking, Likejacking (where Facebook’s like button is targeted), HTTP cookies, zombie cookies or Flash cookies (Local Shared Objects or LSOs); installing adware, viruses, spyware such as Trojan horses (to gain access to users’ personal computers via cracking) or other malware including online banking theft using man-in-the-browser attacks.

Vulnerabilities in the web browser software itself can be minimized by keeping browser software updated, but will not be sufficient if the underlying operating system is compromised, for example, by a rootkit. Some sub-components of browsers such as scripting, add-ons, and cookies are particularly vulnerable (“the confused deputy problem”) and also need to be addressed.

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