XSS and XSRF

Cross-Site Scripting (XSS)

XSS is an attack where the attacker manages to inject malicious scripts into content that is delivered to the other users. These scripts execute within the context of the user's browser under the domain of the legitimate site, which can lead to unauthorized access to session tokens, cookies, or other sensitive information that the browser handles.

Cross-Site Request Forgery (CSRF)

CSRF, on the other hand, tricks the victim into submitting a malicious request. It leverages the identity and privileges of the victim to perform an undesired function on their behalf. For instance, if a user is currently authenticated on a site, the site trusts this user and any requests that they make. CSRF exploits this trust by making the user perform actions without their knowledge, like transfering funds or changing their email address.

Key Differences

• Execution Context: XSS exploits the trust that a user has for a perticular site, whereas CSRF exploits the trust that a site has for a user who is authenticated.
• Payload Delivery: XSS involves the delivery of a payload (malicious script) to a web application, which then gets executed within the user's browser. CSRF involves sending a malicious request from the victim's browser to a web application where they are authenticated to perform actions unwittingly.

Mitigation Strategies:

For XSS

• Sanitize input to ensure that it does not contain executable code before it is output to other users.
• Use Content Security Policy (CSP) headers to restrict the sources of executable scripts.
• Employ proper encoding and escaping of user output to prevent malicious content from becoming executable.

For CSRF

• Use anti-CSRF tokens which ensures that only requests made from within the site are honored.
• Double-checking the origin with standard headers like the Origin and Referer can also help mitigate CSRF.
• Implement same-site cookies which restrict cookies to the same site, preventing CSRF by not allowing cookies to be sent with requests initiated from foreign sites.