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This article mainly shows you "XSS cross-site script how to bypass", the content is easy to understand, clear, hope to help you solve your doubts, the following let the editor lead you to study and learn "XSS cross-site script how to bypass" this article.

I. Overview of XSS (Cross-site scripting)

Cross-site scripting (Cross-Site Scripting, referred to as XSS or cross-site scripting or cross-site scripting attacks) is a kind of security vulnerability attack technology aimed at website applications, and it is a kind of code injection. It allows malicious users to inject code into the web page, and other users will be affected when they browse the web. After a successful attack using XSS code, a malicious user may gain high privileges (such as performing some actions), private web content, conversations, cookie, and so on.

XSS vulnerabilities have always been evaluated as the most harmful vulnerabilities in web vulnerabilities and have been ranked among the top three in OWASP TOP10.

XSS is a vulnerability that occurs in front-end browsers, so it also harms front-end users.

The main reason for the XSS vulnerability is that the program does not properly handle the input and output, which causes the "carefully constructed" character output to be parsed and executed by the browser as valid code at the front end, thus causing harm.

Therefore, in the prevention of XSS vulnerabilities, it is generally handled by "filtering the input" and "escaping the output":

Input filtering: filter input and do not allow character input that may cause XSS attacks

Output escape: appropriate escape of output to the front end according to the location of the output point

2. Some deformations of XSS 1, uppercase and double case bypass

ALert (1)

Alert (1)

2. A label

Test

Test

3. Src attribute

4. Take advantage of events to bypass

Can be bypassed

2. When filtering is strict, javascript will also be filtered.

Input keywords such as script, on, javascript, etc., and grab the package to find that it has been processed.

Build payload:javascr%0aipt:alert (1); (enter it in url, or grab the package to modify it) here use% 0a or% 0D to achieve the effect of line wrapping to bypass

3. How to bypass alert keywords

Input alert is detected by waf and cannot be bypassed

Change the function to build payload:confirm (/ xss/); (besides confirm, you can also use prompt instead of alert) to bypass

4. Bypass the whitelist

In dvwa shooting range, the difficulty of xssdom high is about whitelist winding; no matter what keyword is entered, it will be redirected.

We can add a # after English, and then we can bypass it by typing in the statement. (add a space between # and the preceding content)

Payload: http://127.0.0.1/dvwa/vulnerabilities/xss_d/?default=English # alert (1)

The above is all the contents of the article "how to bypass XSS cross-site scripts". Thank you for reading! I believe we all have a certain understanding, hope to share the content to help you, if you want to learn more knowledge, welcome to follow the industry information channel!

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