第一次参加，写得不怎么好，还请多多指教🙇♂️
题目
启动游戏后可以明显发现游戏存在加速、自瞄、透视等问题。
首先判断虚幻引擎版本，我们可以直接在AndroidManifest.xml中找到UE4.27
对所有so文件进行分析。首先利用偷懒的方法，将so文件通过Virustotal计算一下hash查看首次上传时间可以得知，除libUE4.so和libGame.so都曾经上传过，是标准库，可以不用看
参考文章https://www.cnblogs.com/revercc/p/17641855.html ，分别找到libUE4.so中三个核心参数的偏移
GWorld 0xAFAC398
GName 0xADF07C0
GUObject 0xAE34A98
然后使用UE4Dumper对SDK进行提取，再进一步分析
异常点1-3：无后座、加速以及加速度
对libGame.so进行分析，可以看到该文件对函数使用控制流平坦化混淆，利用IDA插件D-810默认配置即可有效去除进行分析。我们可以留意到有几个异或函数对字符串进行了加密，由于字符串不多这里手动恢复标注即可。
这个so通过.init_array调用函数，通过pthread_create创建新线程，在0x1B9C通过读取/proc/self/maps等方法获取libUE4.so的基址，然后下面通过基址+偏移计算得到UE4中关键参数的地址
在下面通过遍历Actors中的元素，找到所要的Actor后，通过偏移计算找到对应要修改的参数
异常点1
根据偏移查找SDK可以得知是开枪时的后坐力，后续通过Frida修改为其他值也可以进一步验证
异常点2、3
同理，根据偏移去查找对应的参数，可知是人物的速度和加速度
修复
这里选择将这三个地方的STR赋值汇编NOP掉，阻止其修改，应用patch，使用MT管理器替换so将apk重新打包签名，即可修复
异常点4：自瞄
在游戏内开枪，可以发现在开枪时视角/枪口被强制面向其中一个cube。对SDK进行分析，通过Frida Hook进一步确认，发现Controller.Actor.Object内的ControlRotation决定视角/枪口，可以修改这个值来实现自瞄
class Rotator {
constructor(Pitch, Yaw, Roll) {
this.Pitch = Pitch;
this.Yaw = Yaw;
this.Roll = Roll;
}
toString() {
return `(${this.Pitch}, ${this.Yaw}, ${this.Roll})`;
}
}
function dumpRotator(rotatorAddr){
const values = Memory.readByteArray(rotatorAddr, 3 * 4);
const rot = new Rotator(
new Float32Array(values, 0, 1)[0],
new Float32Array(values, 4, 1)[0],
new Float32Array(values, 8, 1)[0]
);
console.log("dump rot", rot);
return rot;
}
function getControlRotation(actorAddr){
var data_addr = ptr(actorAddr).add(0x288);
var rot = dumpRotator(data_addr);
return rot;
}
function writeControlRotation(actorAddr, a, b, c){
ptr(actorAddr).add(0x288).writeFloat(a);
ptr(actorAddr).add(0x288+4).writeFloat(b);
ptr(actorAddr).add(0x288+8).writeFloat(c);
}
因此可以对Actor列表里的PlayerController+0x288的位置下一个写硬件断点，在其被修改时栈回溯找到修改函数。
使用stackplz断点，可以发现正常移动视角时，堆栈情况如hit_count:4，而开枪时则hit_count:3的情况，对比两种情况，因为两种情况都要进入#00所在的函数，因此不好patch。通过frida replace置空#01所在函数，可以发现无法正常开枪，因此该函数与开枪有关系，在这之前也不能动。因此只能对#01所在的函数跳转BLRpatch成NOP，阻止其修改ControlRotation，即可修复。
异常点5：子弹乱飞
在修复自瞄后开枪会发现，子弹并不朝着准星瞄准的方向发射，在查阅相关资料后，得知子弹发射时会通过GunOffset、Location和Rotation等参数计算出发射位置及方向。使用Frida对相关参数进行获取可发现GunOffset这一参数被设置为(100, 0, 10)，且通过硬件断点确定该参数在开枪时会被读取。将其修改为(0, 0, 20)后，子弹乱飞情况有所缓解，但未能彻底解决，测试在Yaw为90，270时（即人物侧对地面文字）影响较大，0，180，360时（即人物正对地面文字）影响较小。
function getGunOffset(actorAddr){
var data_addr = ptr(actorAddr).add(0x500);
dumpVector(data_addr);
}
function writeGunOffset(actorAddr, x, y, z){
ptr(actorAddr).add(0x500).writeFloat(x);
ptr(actorAddr).add(0x500+4).writeFloat(y);
ptr(actorAddr).add(0x500+8).writeFloat(z);
}
writeGunOffset(actorAddrs["FirstPersonCharacter_C"], 0, 0, 20);
在射击函数中，也就是前面自瞄修复的下面，可以看到0x670FBAC的函数中有两个rand函数。将其patch成固定值后，此处我patch成0x7fffff(0xffffff/2)后运行发现小球能够以相对稳定的角度射出，说明此处随机数确实与前面小球左右横跳的情况有关
但仍未弄清楚此处计算结果与ControlRotation还会如何运算。在0x8D2ED80、0x8D2E214的函数里面，可见ActorSpawning的字符串以及对UObject列表等进行修改，此处应该生成了Projectile。本人猜想是需要在这附近对生成子弹的角度修改为ControlRotation，使小球恢复向玩家前方射出，参考UE官方示例代码https://dev.epicgames.com/documentation/zh-cn/unreal-engine/3---implementing-projectiles?application_version=4.27#%E5%AE%9E%E7%8E%B0%E5%8F%91%E5%B0%84%E5%87%BD%E6%95%B0
对应一下
刚好符合SpawnActor的构造，1个指针+4个参数，使用脚本hook一下第3个参数
上面是传入该函数的Rotation，下面是PlayerController的Rotation，可见刚好写反（此处调试时已把rand patch掉），把传参改回来就行
var func_addr = moduleBase.add(0x8D2ED80)
Interceptor.attach(func_addr, {
onEnter: function (args) {
dumpRotator(ptr(args[3]));
var playerRotation = getControlRotation(actorAddrs["PlayerController"]);
ptr(args[3]).writeFloat(playerRotation.Pitch);
ptr(args[3]).add(4).writeFloat(playerRotation.Yaw);
},
onLeave: function (retval) {
}
});
此时子弹即可正常向前方射出，但是准心偏下，这个就需要慢慢调参解决
异常点6：透视
可以看到FirstPersonCharacter_C和ThirdPersonCharacter都被渲染成红色，可以猜测二者被应用同一修改
网上查找过相关资料，透视可通过渲染自定义深度实现，Frida测试过这里并没有开启该参数
function getRenderCustomDepth(actorAddr){
var value = ptr(actorAddr).add(0x212).readU8();
var bitValue = (value >> 3) & 1;
return bitValue;
}
function getAllRenderCustomDepth(){
const actors = getActorsAddr();
for (const actorName in actors) {
if (actors.hasOwnProperty(actorName)) {
const actorAddr = actors[actorName];
try {
var value = getRenderCustomDepth(actorAddr);
console.log(`RenderCustomDepth of ${actorName} at ${actorAddr}: ${value}`);
} catch (e) {
console.error(`Failed to get RenderCustomDepth of ${actorName} at ${actorAddr}: ${e}`);
}
}
}
}
由于对UE4渲染这方面实在不熟悉，不清楚该功能如何实现。猜想可能是从源码上修改了Character.Pawn.Actor.Object的深度，使其渲染在其他Actor的顶层，同时使其渲染成红色。
相关Frida脚本
var moduleBase;
var GWorld;
var GWorld_Ptr_Offset = 0xAFAC398;
var GName;
var GName_Offset = 0xADF07C0;
var GObjects;
var GObjects_Offset = 0xAE34A98;
var actorAddrs
var offset_UObject_InternalIndex = 0xC;
var offset_UObject_ClassPrivate = 0x10;
var offset_UObject_FNameIndex = 0x18;
var offset_UObject_OuterPrivate = 0x20;
var GUObject = {
getClass: function (obj) {
return ptr(obj).add(offset_UObject_ClassPrivate).readPointer();
},
getNameId: function (obj) {
try {
return ptr(obj).add(offset_UObject_FNameIndex).readU32();
}
catch (e) {
return 0;
}
},
getName: function(obj) {
if (this.isValid(obj)){
return getFNameFromID(this.getNameId(obj));
} else {
return "None";
}
},
getClassName: function(obj) {
if (this.isValid(obj)) {
var classPrivate = this.getClass(obj);
return this.getName(classPrivate);
} else {
return "None";
}
},
isValid: function(obj) {
return (ptr(obj) > 0 && this.getNameId(obj) > 0 && this.getClass(obj) > 0);
}
}
function getFNameFromID(index) {
var FNameStride = 0x2
var offset_GName_FNamePool = 0x30;
var offset_FNamePool_Blocks = 0x10;
var offset_FNameEntry_Info = 0;
var FNameEntry_LenBit = 6;
var offset_FNameEntry_String = 0x2;
var Block = index >> 16;
var Offset = index & 65535;
var FNamePool = GName.add(offset_GName_FNamePool);
var NamePoolChunk = FNamePool.add(offset_FNamePool_Blocks + Block * 8).readPointer();
var FNameEntry = NamePoolChunk.add(FNameStride * Offset);
try {
if (offset_FNameEntry_Info !== 0) {
var FNameEntryHeader = FNameEntry.add(offset_FNameEntry_Info).readU16();
} else {
var FNameEntryHeader = FNameEntry.readU16();
}
} catch(e) {
return "";
}
var str_addr = FNameEntry.add(offset_FNameEntry_String);
var str_length = FNameEntryHeader >> FNameEntry_LenBit;
var wide = FNameEntryHeader & 1;
if (wide) return "widestr";
if (str_length > 0 && str_length < 250) {
var str = str_addr.readUtf8String(str_length);
return str;
} else {
return "None";
}
}
function set(modulename) {
moduleBase = Module.findBaseAddress(modulename);
GWorld = moduleBase.add(GWorld_Ptr_Offset).readPointer();
GName = moduleBase.add(GName_Offset);
GObjects = moduleBase.add(GObjects_Offset);
}
function getActorsAddr(){
var Level_Offset = 0x30
var Actors_Offset = 0x98
var Level = GWorld.add(Level_Offset).readPointer()
var Actors = Level.add(Actors_Offset).readPointer()
var Actors_Num = Level.add(Actors_Offset).add(8).readU32()
var actorsAddr = {};
for(var index = 0; index < Actors_Num; index++){
var actor_addr = Actors.add(index * 8).readPointer()
var actorName = GUObject.getName(actor_addr)
actorsAddr[actorName] = actor_addr;
}
return actorsAddr;
}
class Vector {
constructor(x, y, z) {
this.x = x;
this.y = y;
this.z = z;
}
toString() {
return `(${this.x}, ${this.y}, ${this.z})`;
}
}
class Rotator {
constructor(Pitch, Yaw, Roll) {
this.Pitch = Pitch;
this.Yaw = Yaw;
this.Roll = Roll;
}
toString() {
return `(${this.Pitch}, ${this.Yaw}, ${this.Roll})`;
}
}
function dumpVector(vectorAddr){
const values = Memory.readByteArray(vectorAddr, 3 * 4);
const vec = new Vector(
new Float32Array(values, 0, 1)[0],
new Float32Array(values, 4, 1)[0],
new Float32Array(values, 8, 1)[0]
);
console.log("dump vec", vec);
return vec;
}
function dumpRotator(rotatorAddr){
const values = Memory.readByteArray(rotatorAddr, 3 * 4);
const rot = new Rotator(
new Float32Array(values, 0, 1)[0],
new Float32Array(values, 4, 1)[0],
new Float32Array(values, 8, 1)[0]
);
console.log("dump rot", rot);
return rot;
}
function getActorLocation(actorAddr){
var functionAddr = moduleBase.add(0x92e16b4);
var getActorLocationFunc = new NativeFunction(functionAddr, 'void', ['pointer', 'pointer', 'pointer']);
var location = Memory.alloc(0x100);
try{
getActorLocationFunc(ptr(actorAddr), location, location);
dumpVector(location);
return location;
}
catch(e){
}
}
function getActorRotation(actorAddr){
var functionAddr = moduleBase.add(0x937BB14);
var getActorRotationFunc = new NativeFunction(functionAddr, 'void', ['pointer', 'pointer', 'pointer']);
var rotation = Memory.alloc(0x100);
try{
getActorRotationFunc(ptr(actorAddr), rotation, rotation);
dumpRotator(rotation);
return rotation;
}
catch(e){
}
}
// function getVector(actorAddr){
// var data_addr = ptr(actorAddr).add(0x500);
// dumpVector(data_addr);
// }
// function writeVector(actorAddr, x, y, z){
// ptr(actorAddr).add(0x500).writeFloat(x);
// ptr(actorAddr).add(0x500+4).writeFloat(y);
// ptr(actorAddr).add(0x500+8).writeFloat(z);
// }
function getGunOffset(actorAddr){
var data_addr = ptr(actorAddr).add(0x500);
dumpVector(data_addr);
}
function writeGunOffset(actorAddr, x, y, z){
ptr(actorAddr).add(0x500).writeFloat(x);
ptr(actorAddr).add(0x500+4).writeFloat(y);
ptr(actorAddr).add(0x500+8).writeFloat(z);
}
function getControlRotation(actorAddr){
var data_addr = ptr(actorAddr).add(0x288);
var rot = dumpRotator(data_addr);
return rot;
}
function writeControlRotation(actorAddr, a, b, c){
ptr(actorAddr).add(0x288).writeFloat(a);
ptr(actorAddr).add(0x288+4).writeFloat(b);
ptr(actorAddr).add(0x288+8).writeFloat(c);
}
// function getFloat(actorAddr){
// var data_addr = ptr(actorAddr).add(0x1a0);
// const values = Memory.readByteArray(data_addr, 4);
// console.log(new Float32Array(values, 0, 1)[0]);
// }
// function writeFloat(actorAddr, value){
// ptr(actorAddr).add(0x52c).writeFloat(value);
// }
function getProjectil(){
// 判断actorAddrs是否有FirstPersonProjectile_C
actorAddrs = getActorsAddr();
if (actorAddrs.hasOwnProperty("FirstPersonProjectile_C")) {
var actorAddr = actorAddrs["FirstPersonProjectile_C"];
var projectileMovement_addr = ptr(actorAddr).add(0x228).readPointer();
console.log(projectileMovement_addr.add(0xec).readFloat());
}
}
function setRenderCustomDepth(actorAddr, bEnabled){
var functionAddr = moduleBase.add(0x8AB9DE8);
var setRenderCustomDepthFunc = new NativeFunction(functionAddr, 'void', ['pointer', 'char']);
setRenderCustomDepthFunc(ptr(actorAddr), bEnabled);
}
function applyCustomDepthToAllActors(bEnabled) {
const actors = getActorsAddr(); // 获取所有Actor地址
for (const actorName in actors) {
if (actors.hasOwnProperty(actorName)) {
const actorAddr = actors[actorName];
try {
setRenderCustomDepth(actorAddr, bEnabled); // 调用函数设置CustomDepth
console.log(`Applied CustomDepth to ${actorName} at ${actorAddr}`);
} catch (e) {
console.error(`Failed to apply CustomDepth to ${actorName} at ${actorAddr}: ${e}`);
}
}
}
}
function setCustomDepthStencilValue(actorAddr, value){
var functionAddr = moduleBase.add(0x8AB9E0C);
var setCustomDepthStencilValueFunc = new NativeFunction(functionAddr, 'void', ['pointer', 'int']);
setCustomDepthStencilValueFunc(ptr(actorAddr), value);
}
function getRenderCustomDepth(actorAddr){
var value = ptr(actorAddr).add(0x212).readU8();
var bitValue = (value >> 3) & 1;
return bitValue;
}
function getAllRenderCustomDepth(){
const actors = getActorsAddr();
for (const actorName in actors) {
if (actors.hasOwnProperty(actorName)) {
const actorAddr = actors[actorName];
try {
var value = getRenderCustomDepth(actorAddr);
console.log(`RenderCustomDepth of ${actorName} at ${actorAddr}: ${value}`);
} catch (e) {
console.error(`Failed to get RenderCustomDepth of ${actorName} at ${actorAddr}: ${e}`);
}
}
}
}
function main(){
Java.perform(function(){
set("libUE4.so");
actorAddrs = getActorsAddr();
writeGunOffset(actorAddrs["FirstPersonCharacter_C"], 0, 0, 20);
});
var func_addr = moduleBase.add(0x8D2ED80)
Interceptor.attach(func_addr, {
onEnter: function (args) {
dumpRotator(ptr(args[3]));
var playerRotation = getControlRotation(actorAddrs["PlayerController"]);
ptr(args[3]).writeFloat(playerRotation.Pitch);
ptr(args[3]).add(4).writeFloat(playerRotation.Yaw);
},
onLeave: function (retval) {
}
});
}
setImmediate(main);
|
发表于 2025-4-19 13:54
|楼主
发表于 2025-4-16 16:10
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