资安学习路上-picoCTF 解题(Web)2

4. Some Assembly Required 1

按右键，检视网页原始码

点击js档看到下面，虽然知道是js档，但有点乱

用(线上Javascript工具，执行看看

接着为了再去混淆度，把常出现的两个参数findMiddlePosition跟navigatePop丢进去，看他的结果，并已编译后的值带入

结果如下

(async() => {  const findMiddlePosition = _0x4e0e;  let leftBranch = await fetch(./JIFxzHyW8W);  let rightBranch = await WebAssembly[instantiate](await leftBranch[arrayBuffer]());  let module = rightBranch[instance];  exports = module["exports"];})();/** * @return {undefined} */function onButtonPress() {  const navigatePop = _0x4e0e;  let params = document["getElementById"](input)[value];  for (let i = 0; i < params["length"]; i++) {    exports[copy_char](params[charCodeAt](i), i);  }  exports["copy_char"](0, params["length"]);  if (exports[check_flag]() == 1) {    document[getElementById](result)[innerHTML] = Correct!;  } else {    document[getElementById](result)[innerHTML] = Incorrect!;  }}

知道是从JIFxzHyW8W下载wasm档，是用copy_char存每个flag，再用check_flag来确认是否正确，用wget指令下载wasm档，在用kali内建wasm2wat将wasm档转成wat档(WebAssembly 文字格式)

用Cat指令得到flag