When testing applications, traffic manipulation and recording is invaluable. The major players in this market are also extendable, allowing the community of researchers to improve functionality with free add-ons. Well-built and supported proxies are powerful weapons in the attacker's arsenal.
Burp Suite is arguably the king when it comes to attack proxies. It allows you to intercept, change, replay, and record traffic out of the box. Burp Suite is highly extendable, with powerful community plugins that integrate with sqlmap (the de facto SQLi exploitation tool), automatically test for privilege escalation, and offer other useful modules:
Proxy: Record, intercept, and modify requests on the fly
Spider: Content discovery with powerful crawling capabilities
Decoder: Unscramble encoded data quickly
Intruder: A highly customizable brute-forcing module
Repeater: Allows the replay of any request previously recorded, with the ability to modify any part of the request itself
Scanner (pro only): A vulnerability scanner that integrates with Burp Collaborator to find obscure vulnerabilities
Collaborator: Aids in the discovery of obscure vulnerabilities, which would normally be missed by traditional scanners
There is a free version of Burp Suite, but the professional edition of the product is well worth the investment. While the free version is perfectly usable for quick tests, it does have some limitations. Notably, the Intruder module is time-throttled, making it useless for large payloads. The Scanner module is also only available in the professional version and it is worth the price. Scanner can quickly find low-hanging fruit and even automatically leverage Collaborator to find out-of-band vulnerabilities. The free version can still intercept, inspect, and replay requests, and it can also alert of any vulnerabilities it has passively detected.
Figure 1.5: The main Burp Suite Free Edition screen
OWASP's Zed Attack Proxy (ZAP) is another really great attack proxy. It is extendable and easy to use. However, it lacks some of the features of Burp Suite; for example, ZAP does not have the extensive active vulnerability scanning capabilities of Burp Suite Pro, nor does it have an automated out-of-band vulnerability discovery system comparable to Collaborator.
However, there is no time-throttling on its version of the Intruder module and all of its features are available out of the box. ZAP is open-source and it is actively worked on by hundreds of volunteers.
Figure 1.6: The main ZAP screen