某红书Shield算法Chomper黑盒调用

从安卓还原算法过程得知需要初始化设置一个Token
这里选择的是一个老版本作为案例，这里也不需要其他多余的部环境操作。
chomper 地址：https://github.com/sledgeh4w/chomper

初始化

从frida-trace无法得知初始化做了什么，只能看到具体的算法调用逻辑。

   863 ms  +[XYSSHandle reqAuthorityWithHeaders:<CFBasicHash 0x283b31740 [0x201426858]>{type = mutable dict, count = 10,
entries =>
    0 : Accept-Language = zh-Hans;q=1, en;q=0.9
    1 : X-B3-TraceId = a4e86b06fbe691f3
    2 : Connection = Keep-Alive
    3 : Mode = rawIp
    4 : X-raw-ptr = 0
    7 : Host = edith.xiaohongshu.com
    9 : User-Agent = discover/7.1 (iPhone; iOS 16.7.10; Scale/2.00) Resolution/750*1334 Version/7.1 Build/7010202 Device/(Apple Inc.;iPhone10,1) NetType/WiFi
    10 : xy-platform-info = platform=iOS&version=7.1&build=7010202&deviceId=C53A986E-875F-4FE2-9C49-BC1DD280E337&bundle=com.xingin.discover
    11 : Accept-Encoding = br;q=1.0, gzip;q=1.0, compress;q=0.5
    12 : xy-common-params = app_id=ECFAAF02&build=7010202&deviceId=C53A986E-875F-4FE2-9C49-BC1DD280E337&device_fingerprint=2025022115160335e8c03be20ba5b6b300c149f76fc3f50123d7e2b8cb1cf6&device_fingerprint1=2025022115160335e8c03be20ba5b6b300c149f76fc3f50123d7e2b8cb1cf6&fid=1740122163-0-0-970427ae7226e33071bdefb4866c668a&identifier_flag=0&lang=zh-Hans&launch_id=761816146&platform=iOS&project_id=ECFAAF&sid=session.1740122519639795203705&t=1740123589&tz=Asia/Shanghai&uis=light&version=7.1
}
 request:0x282c35e00 bodyData:nil]

  ```

### dlopen监控
无法从frida-trace得知初始化的值，只能在dlopen 之后做

![file](https://zhaoxincheng.com/wp-content/uploads/2025/02/2025022206160556.png)

代码如下：从frida-trace得知XYSSHandle的相关初始化函数。

let dlopen = Module.findExportByName(null, "dlopen");

Interceptor.attach(dlopen, {
onEnter: function (args) {
this.hook = false
if ((args[0].readUtf8String() + '').indexOf("XYSecureShield") > -1) {
this.hook = true;
}
}, onLeave: function (retval) {
if (this.hook) {
var methodName = "+ setup:build:key:";
var hooking = ObjC.classes["XYSSHandle"][methodName];
// console.log(hooking, 'hooking')
Interceptor.attach(hooking.implementation, {
onEnter: function (args) {
console.log(ObjC.Object(args[2]), ObjC.Object(args[3]), ObjC.Object(args[4]))
}, onLeave: function (returnValues) {
}
});
var methodName = "+ setToken:";
var hooking = ObjC.classes["XYSSHandle"][methodName];
// console.log(hooking, 'hooking')
Interceptor.attach(hooking.implementation, {
onEnter: function (args) {
console.log("setToken", ObjC.Object(args[2]))
}, onLeave: function (returnValues) {
}
});
let module_name = "XYSecureShield"
var base_addr = Module.findBaseAddress(module_name);
// console.log(hooking, 'hooking')
Interceptor.attach(base_addr.add(0x969C), {
onEnter: function (args) {
console.log("0x969C")
}, onLeave: function (returnValues) {
}
});
}
}
});

### Chomper调用初始化
基础框架请看上一篇文章 [某手sig3-ios算法Chomper黑盒调用](https://zhaoxincheng.com/index.php/2025/02/20/%E6%9F%90%E6%89%8Bsig3-ios%E7%AE%97%E6%B3%95%E4%BD%BF%E7%94%A8chomper%E8%B0%83%E7%94%A8/ "某手sig3-ios算法Chomper黑盒调用")
如下代码就初始化完成

objc.msg_send("XYSSHandle", "setup:build:key:", pyobj2nsobj(emu, "ECFAAF02"), pyobj2nsobj(emu, "7010202"),
pyobj2nsobj(emu, "C53A986E-875F-4FE2-9C49-BC1DD280E337"))
objc.msg_send("XYSSHandle", "setToken:", pyobj2nsobj(emu,
"snFxyd29qfTBy1PRP4vNvhD2NU4pon75wsIrrZQTR3n6MgwmC3vh9hSLJTqbC4kM8+AdHzW93wplGjU+zZbwiGYUQE8nbB49FTj0alqXaX0zJ+Msj3dNPNPoTcpXB34G"))

##主动调用
### 构造NSMutableURLRequest对象
这里还是比较复杂一点，根据frida-trace的代码得知，需要传入一个NSMutableURLRequest对象，需要构造。问下ai
![file](https://zhaoxincheng.com/wp-content/uploads/2025/02/2025022206070636.png)
如下代码就构造好req对象。

NSURL_addr = objc.msg_send("NSURL", "URLWithString:", pyobj2nsobj(emu,
"https://www.xiaohongshu.com/api/im/v2/messages/unread"))
req_obj = objc.msg_send("NSMutableURLRequest", "requestWithURL:", NSURL_addr)

req_obj = objc.msg_send(req_obj, "path:", NSURL_addr)

### 构造Headers
直接使用作者的pyobj2nsobj，如下代码就是将py的dict转为oc里面的dic

if isinstance(obj, dict):
ns_obj = objc.msg_send("NSMutableDictionary", "dictionary")

    for key, value in obj.items():
        ns_key = pyobj2nsobj(emu, key)
        ns_value = pyobj2nsobj(emu, value)

        objc.msg_send(ns_obj, "setObject:forKey:", ns_value, ns_key)

下面就是算法入参

pyobj2nsobj(emu, {
"xy-platform-info": "2",
"xy-common-params": "1",
})

### 算法调用
上边的构造传入，并主动调用之后就会得出结果。

XYSSHandle_addr = objc.msg_send("XYSSHandle", "reqAuthorityWithHeaders:request:bodyData:",
pyobj2nsobj(emu, {
"xy-platform-info": "2",
"xy-common-params": "1",
}), req_obj, pyobj2nsobj(emu, "111".encode()))
print("Shield result: %s", emu.read_string(objc.msg_send(XYSSHandle_addr, "cStringUsingEncoding:", 4)))

![file](https://zhaoxincheng.com/wp-content/uploads/2025/02/2025022206145063.png)