xctf web之 simple_js
输入密码后
查看源码
<html>
<head>
<title>JStitle>
<script type="text/javascript">
function dechiffre(pass_enc){
var pass = "70,65,85,88,32,80,65,83,83,87,79,82,68,32,72,65,72,65";
var tab = pass_enc.split(',');
var tab2 = pass.split(',');var i,j,k,l=0,m,n,o,p = "";i = 0;j = tab.length;
k = j + (l) + (n=0);
n = tab2.length;
for(i = (o=0); i < (k = j = n); i++ ){o = tab[i-l];p += String.fromCharCode((o = tab2[i]));
if(i == 5)break;}
for(i = (o=0); i < (k = j = n); i++ ){
o = tab[i-l];
if(i > 5 && i < k-1)
p += String.fromCharCode((o = tab2[i]));
}
p += String.fromCharCode(tab2[17]);
pass = p;return pass;
}
String["fromCharCode"](dechiffre("\x35\x35\x2c\x35\x36\x2c\x35\x34\x2c\x37\x39\x2c\x31\x31\x35\x2c\x36\x39\x2c\x31\x31\x34\x2c\x31\x31\x36\x2c\x31\x30\x37\x2c\x34\x39\x2c\x35\x30"));
h = window.prompt('Enter password');
alert( dechiffre(h) );
script>
head>
html>
不断的切换输入的密码 发现中间这一部分都是没有改变的
觉得可能没什么作用
重点分析
String["fromCharCode"](dechiffre("\x35\x35\x2c\x35\x36\x2c\x35\x34\x2c\x37\x39\x2c\x31\x31\x35\x2c\x36\x39\x2c\x31\x31\x34\x2c\x31\x31\x36\x2c\x31\x30\x37\x2c\x34\x39\x2c\x35\x30"));
\x35\x35\x2c\x35这一个长串子是十六进制转义字符，其中的最后两位16进制数。
我们直接用python print 输出就能得到
数组[55,56,54,79,115,69,114,116,107,49,50]
.将得到的数字分别进行ascii处理，可得到字符串 786OsErtk12 也就是flag
a = [55,56,54,79,115,69,114,116,107,49,50]
c = ""
for i in a:
b = chr(i)
c = c + b
print(c)