Street network storage type XSS (XSS black box analysis skills)

Street network has a persistent xss that can execute external js
When the sharing status is not strictly filtered, the stored xss is generated. First, we add an image and click "Post New Things". Capture packets to find that the image parameter exists and the parameter is controllable. Traditionally, after the parameter is submitted to the server, it is found that the original src attribute is blank, indicating that it has been filtered and then tested multiple times, I think it is possible that the server determines whether the end Of the image parameter is a suffix of jpg or other image formats. After the test, it is found that this is indeed the case, because double quotation marks are not used to filter data, it is easy to do so. The parameter is submitted to the server again, and the window is displayed successfully.
Hazards: attackers can execute arbitrary external js to cause advertisement worms or something.Solution:

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