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This article introduces the knowledge of "how to solve the problem of infinite debugger when JavaScript is in reverse". In the operation of actual cases, many people will encounter such a dilemma, so let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!

The following is the text:

Today, my friends should wish to write about two cases of infinite debugger. (in fact, it's all very simple, as long as you master one or two operating points.)

For partners who have been dealt with in some cases, they may need to clear the cookie under the corresponding domain before triggering unlimited debugger.

1. The address of FDA is: http://app1.sfda.gov.cn/datasearch/face3/base.jsp?tableId=120&tableName=TABLE120&title=%CA%B3%C6%B7%C9%FA%B2%FA%D0%ED%BF%C9%BB%F1%D6%A4%C6%F3%D2%B5(SC)&bcId=145275419693611287728573704379

After typing the address in chrome, open f12, which brings us to today's topic:

Beautify the code and find that it is a debugger. At this time, in the console console, rewrite the function

After rewriting, click X to close the f12 window (remember not to refresh the page, because refreshing is equivalent to reloading, and the rewriting function is meaningless), close and then reopen F12 and start debugger again

An infinite debugger that calculates the time difference. Look at it according to the call stack.

According to the code, it is found that it is a string executed by eval, and the _ $jQ function is rewritten at this time.

The rewritten function has no specific meaning, so eval has nothing to execute, close f12 at this time, reopen it, and find that there will be no more debugger. (ps: whether it's loading another page or refreshing it, as long as the browser reloads the js with the debugger statement, it will start debug, so erase the debugger first, and then go to the breakpoint to analyze what you want.)

two,

Nubia Forum, address: https://bbs.nubia.cn/

Because this is a case where js generates cookie, the mechanism for triggering debugger is different.

First clear the cookie under the site (ps: some cases may also need to clear storage), type the address, open f12, and then enter in the browser address bar, and debugger will appear.

Check several layers of call stack to find the key points.

A direct call, a setInterval, the old rule rewrites the _ 0x4db1c function

Because this case is relatively simple, I would like to say a few more words. Because of the particularity of this case, after you close f12, the cookie is generated, and then the page data is available, and still can not analyze the generation rules of cookie, so make a breakpoint before the function is executed.

Do not close f12, refresh the page, break at our breakpoint

At this time, the objective function _ 0x4db1c is rewritten in the console, but if you continue to execute after the rewrite, you will still not see the cookie generation rules, so do not take any action after the rewrite and make a breakpoint at the key position (ps: this case is a classic js-generated cookie case, that is, the process of arg1 generating arg2, and I will hit the breakpoint directly)

This is the part. After hitting the breakpoint, click the button at this time to continue.

It's in our expected position, so let's start a pleasant analysis.

This is the end of the content of "how to solve the problem of infinite debugger encountered in the reverse of JavaScript". Thank you for reading. If you want to know more about the industry, you can follow the website, the editor will output more high-quality practical articles for you!

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