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CIS Control 18

Application Software Security

Key Principle:

Manage the security life cycle of all in-house developed and acquired software in order to prevent, detect, and correct security weaknesses.

Why is this CIS Control critical?

Attacks often take advantage of vulnerabilities found in web-based and other application software. Vulnerabilities can be present for many reasons, including coding mistakes, logic errors, incomplete requirements, and failure to test for unusual or unexpected conditions. Examples of specific errors include: the failure to check the size of user input; failure to filter out unneeded but potentially malicious character sequences from input streams; failure to initialize and clear variables; and poor memory management allowing flaws in one part of the software to affect unrelated (and more security critical) portions. There is a flood of public and private information about such vulnerabilities available to attackers and defenders alike, as well as a robust marketplace for tools and techniques to allow “weaponization” of vulnerabilities into exploits. Attackers can inject specific exploits, including buffer overflows, SQL injection attacks, cross-site scripting, cross-site request forgery, and click-jacking of code to gain control over vulnerable machines. In one attack, more than 1 million web servers were exploited and turned into infection engines for visitors to those sites using SQL injection. During that attack, trusted websites from state governments and other organizations compromised by attackers were used to infect hundreds of thousands of browsers that accessed those websites. Many more web and non-web application vulnerabilities are discovered on a regular basis.

Main Points:
  • For all acquired application software, check that the version you are using is still supported by the vendor. If not, update to the most current version and install all relevant patches and vendor security recommendations.
  • Protect web applications by deploying web application firewalls (WAFs) that inspect all traffic flowing to the web application for common web application attacks, including but not limited to cross-site scripting, SQL injection, command injection, and directory traversal attacks. For applications that are not web-based, specific application firewalls should be deployed if such tools are available for the given application type. If the traffic is encrypted, the device should either sit behind the encryption or be capable of decrypting the traffic prior to analysis. If neither option is appropriate, a host-based web application firewall should be deployed.

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