Frame Injection

An attacker might use this vulnerability to redirect users to other malicious websites that are used for phishing and similar attacks. Additionally they might place a fake login form in the frame, which can be used to steal credentials from your users.

It should be noted that attackers can also abuse injected frames in order to circumvent certain client side security mechanisms. Developers might overwrite functions to make it harder for attackers to abuse a vulnerability.

If an attacker uses a javascript: URL as src attribute of an iframe, the malicious JavaScript code is executed under the origin of the vulnerable website. However, it has access to a fresh window object without any overwritten functions.

• Where possible do not use users' input for URLs.
• If you definitely need dynamic URLs, make a list of valid accepted URLs and do not accept other URLs.
• Ensure that you only accept URLs which are located on accepted domains.
• Use CSP to whitelist iframe source URLs explicitly.