本文主要是介绍bugku Web4，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！
首先进入题面就是常见的提交框，老规矩直接查看源代码
在这里我们发现了有个js它定义了两个变量并采用eval函数算一些什么东西
| var p1 = '%66%75%6e%63%74%69%6f%6e%20%63%68%65%63%6b%53%75%62%6d%69%74%28%29%7b%76%61%72%20%61%3d%64%6f%63%75%6d%65%6e%74%2e%67%65%74%45%6c%65%6d%65%6e%74%42%79%49%64%28%22%70%61%73%73%77%6f%72%64%22%29%3b%69%66%28%22%75%6e%64%65%66%69%6e%65%64%22%21%3d%74%79%70%65%6f%66%20%61%29%7b%69%66%28%22%36%37%64%37%30%39%62%32%62'; | |
| var p2 = '%61%61%36%34%38%63%66%36%65%38%37%61%37%31%31%34%66%31%22%3d%3d%61%2e%76%61%6c%75%65%29%72%65%74%75%72%6e%21%30%3b%61%6c%65%72%74%28%22%45%72%72%6f%72%22%29%3b%61%2e%66%6f%63%75%73%28%29%3b%72%65%74%75%72%6e%21%31%7d%7d%64%6f%63%75%6d%65%6e%74%2e%67%65%74%45%6c%65%6d%65%6e%74%42%79%49%64%28%22%6c%65%76%65%6c%51%75%65%73%74%22%29%2e%6f%6e%73%75%62%6d%69%74%3d%63%68%65%63%6b%53%75%62%6d%69%74%3b'; | |
| eval(unescape(p1) + unescape('%35%34%61%61%32' + p2)); |
额．．排版有点难看
不过很明显两个变量都是url编码 我们解密下可以得到
p1=function checkSubmit(){var a=document.getElementById("password");if("undefined"!=typeof a){if("67d709b2b
p2=aa648cf6e87a7114f1"==a.value)return!0;alert("Error");a.focus();return!1}}document.getElementById("levelQuest").οnsubmit=checkSubmit;
然后我们分析
eval(unescape(p1) + unescape('%35%34%61%61%32' + p2)); |
于是我们把三次的结果拼装起来得到p1=function checkSubmit(){var a=document.getElementById("password");if("undefined"!=typeof a){if("67d709b2b54aa2aa648cf6e87a7114f1"==a.value)return!0;alert("Error");a.focus();return!1}}document.getElementById("levelQuest").οnsubmit=checkSubmit;
然后便得到值67d709b2b54aa2aa648cf6e87a7114f1放入输入框即可获得flag
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