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Web Application Security

There is no doubt that web application security is a current and newsworthy subject. For all concerned, the stakes are high: for businesses that derive increas- ing revenue from Internet commerce, for users who trust web applications with sensitive information, and for criminals who can make big money by stealing payment details or compromising bank accounts. Reputation plays a critical role. Few people want to do business with an insecure website, so few organizations want to disclose details about their own security vulnerabilities or breaches.

As with any new class of technology, web applications have brought with them a new range of security vulnerabilities. The set of most commonly encountered defects has evolved somewhat over time. New attacks have been conceived that were not considered when existing applications were developed. Some problems have become less prevalent as awareness of them has increased. New technologies have been developed that have introduced new possibilities for exploitation. Some categories of flaws have largely gone away as the result of changes made to web browser software.

The most serious attacks against web applications are those that expose sensitive data or gain unrestricted access to the back-end systems on which the application is running. High-profile compromises of this kind continue to occur frequently. For many organizations, however, any attack that causes system downtime is a critical event. Application-level denial-of-service attacks can be used to achieve the same results as traditional resource exhaustion attacks against infrastructure. However, they are often used with more subtle techniques and objectives. They may be used to disrupt a particular user or service to gain a competitive edge against peers in the realms of financial trad- ing, gaming, online bidding, and ticket reservations.

Throughout this evolution, compromises of prominent web applications have remained in the news. There is no sense that a corner has been turned and that these security problems are on the wane. By some measure, web application security is today the most significant battleground between attackers and those with computer resources and data to defend, and it is likely to remain so for the foreseeable future.

Below are the most common categories of vulnerability:

Broken authentication

This category of vulnerability encom- passes various defects within the application’s login mechanism, which may enable an attacker to guess weak passwords, launch a brute-force attack, or bypass the login.

Broken access controls

This involves cases where the application fails to properly protect access to its data and functionality, potentially enabling an attacker to view other users’ sensitive data held on the server or carry out privileged actions.

SQL injection

SQL Injection enables an attacker to submit crafted input to interfere with the application’s interaction with back-end databases. An attacker may be able to retrieve arbitrary data from the application, interfere with its logic, or execute commands on the database server itself.

Cross-site scripting

Cross-site Scripting (XSS) enables an attacker to target other users of the application, potentially gaining access to their data, performing unauthorized actions on their behalf, or carrying out other attacks against them.

Information leakage

This involves cases where an application divulges sensitive information that is of use to an attacker in developing an assault against the application, through defective error handling or other behavior.

Cross-site request forgery

This flaw means that application users can be induced to perform unintended actions on the application within their user context and privilege level. The vulnerability allows a malicious web site visited by the victim user to interact with the applica- tion to perform actions that the user did not intend.


Published on Sat 01 June 2013 by Sue Romford in Security with tag(s): web applications security