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[原创]内存解析libmono函数地址
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发表于: 2021-2-2 18:12
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启动时候HookDlopen，并在加载libmono.so的时候对导出函数 mono_image_open_from_data_with_name 进行Hook 拿到加载进来的dll的image对象，返回值就是一个_MonoImage结构体指针
关注上图中的
*raw_data dll在内存中的起始地址
raw_data_len dll的长度
即可写出，记录下arr_imgs_addr 和 arr_imgs_name
以上为启动的时候就进行Hook可以拿到Image结构体，不在启动的时候Hook同样也可以拿到
使用导出函数中的 mono_image_loaded 即可
对于如何拿到method对象的话，我们还是冲导出函数入手，使用IDA查看一下导出函数，看看关键字method，可以看到这些函数，选几个长得像那么回事的函数去源码搜搜
搜了一下源码得到一下声明
第一个token我们不好找，放弃
第二个flags也不好找，放弃
第四个显然就是一个通过class来遍历method的方法，可用但是没必要
所以看参数我们要去找 MonoClass，那继续去找导出函数
于是找到了 mono_class_from_nam() 函数
由此我们需要的参数也都筹齐了，写出一下hook代码
运行见效果：
简单的看了一下导出函数，发现有一个 mono_runtime_invoke 传参就是 MonoMethod
于是可以尝试主动调用
这里选了一个get_identifier 来主动调用，可以发现没问题
（但是这里仅限于不带参数的Static方法）
看着这个mono_runtime_invoke(MonoMethod method, void obj, void **params,MonoObject **exc)的声明参数就不想看它了，有更简单的方法，这里就简述一下这个简单的方法
我们换一个思路，总所周知，dll是被加载进去内存在动态编译的，这里我们手动调用mono_compile_method来编译这个MonoMethod即可得到类似于il2cpp中的MethodInfo的函数指针，详见下图
/**
* 启动时候Hook mono_image_open_from_data_with_name 记录dll的起始位置，名称
*/
function HookMono() { //MonoImage *mono_image_open_from_data_with_name (char *data, uint32_t data_len, mono_bool need_copy,MonoImageOpenStatus *status, mono_bool refonly, const char *name);
Interceptor.attach(Module.findExportByName(soName,"mono_image_open_from_data_with_name"), {
onEnter: function (args) {
this.name = args[5].readCString()
this.size = args[1].toInt32()
},
onLeave: function (ret) {
var t_ret = ret
LOG("[*] "+t_ret + "\t"+this.name,LogColor.C36)
var t_arr = this.name.split("/")
var t_name = t_arr[(t_arr.length)-1].split(".dll")[0]
arr_imgs_addr.push(String(t_ret))
arr_imgs_name.push(t_name)
}
});
}/**
* 启动时候Hook mono_image_open_from_data_with_name 记录dll的起始位置，名称
*/
function HookMono() { //MonoImage *mono_image_open_from_data_with_name (char *data, uint32_t data_len, mono_bool need_copy,MonoImageOpenStatus *status, mono_bool refonly, const char *name);
Interceptor.attach(Module.findExportByName(soName,"mono_image_open_from_data_with_name"), {
onEnter: function (args) {
this.name = args[5].readCString()
this.size = args[1].toInt32()
},
onLeave: function (ret) {
var t_ret = ret
LOG("[*] "+t_ret + "\t"+this.name,LogColor.C36)
var t_arr = this.name.split("/")
var t_name = t_arr[(t_arr.length)-1].split(".dll")[0]
arr_imgs_addr.push(String(t_ret))
arr_imgs_name.push(t_name)
}
});
}MonoImage *mono_image_loaded (const char *name);
MonoImage *mono_image_loaded (const char *name);
MonoMethod *mono_get_method (MonoImage *image, uint32_t token, MonoClass *klass);
MonoMethod *mono_class_get_method_from_name (MonoClass *klass, const char *name, int param_count);
MonoMethod *mono_class_get_method_from_name_flags (MonoClass *klass, const char *name, int param_count, int flags);
MonoMethod *mono_class_get_methods (MonoClass* klass, void **iter);
MonoMethod *mono_get_method (MonoImage *image, uint32_t token, MonoClass *klass);
MonoMethod *mono_class_get_method_from_name (MonoClass *klass, const char *name, int param_count);
MonoMethod *mono_class_get_method_from_name_flags (MonoClass *klass, const char *name, int param_count, int flags);
MonoMethod *mono_class_get_methods (MonoClass* klass, void **iter);
//函数声明
MonoClass *mono_class_from_name (MonoImage *image, const char* name_space, const char *name);
struct _MonoMethod { guint16 flags; /* method flags */
guint16 iflags; /* method implementation flags */
guint32 token;
MonoClass *klass; /* To what class does this method belong */
MonoMethodSignature *signature;
/* name is useful mostly for debugging */
const char *name;
.....
}struct _MonoClass { MonoClass *element_class;
MonoClass *cast_class;
MonoClass **supertypes;
guint16 idepth;
guint8 rank;
int instance_size;
......
MonoImage *image;
const char *name;
const char *name_space;
......
}struct _MonoMethodSignature { MonoType *ret;
#ifdef MONO_SMALL_CONFIG guint8 param_count;
gint8 sentinelpos;
unsigned int generic_param_count : 5;
#else guint16 param_count;
gint16 sentinelpos;
unsigned int generic_param_count : 16;
#endif unsigned int call_convention : 6;
unsigned int hasthis : 1;
unsigned int explicit_this : 1;
unsigned int pinvoke : 1;
unsigned int is_inflated : 1;
unsigned int has_type_parameters : 1;
MonoType *params [MONO_ZERO_LEN_ARRAY];
};//函数声明
MonoClass *mono_class_from_name (MonoImage *image, const char* name_space, const char *name);
struct _MonoMethod { guint16 flags; /* method flags */
guint16 iflags; /* method implementation flags */
guint32 token;
MonoClass *klass; /* To what class does this method belong */
MonoMethodSignature *signature;
/* name is useful mostly for debugging */
const char *name;
.....
}struct _MonoClass { MonoClass *element_class;
MonoClass *cast_class;
MonoClass **supertypes;
guint16 idepth;
guint8 rank;
int instance_size;
......
MonoImage *image;
const char *name;
const char *name_space;
......
}struct _MonoMethodSignature { MonoType *ret;
#ifdef MONO_SMALL_CONFIG guint8 param_count;
gint8 sentinelpos;
unsigned int generic_param_count : 5;
#else guint16 param_count;
gint16 sentinelpos;
unsigned int generic_param_count : 16;
#endif unsigned int call_convention : 6;
unsigned int hasthis : 1;
unsigned int explicit_this : 1;
unsigned int pinvoke : 1;
unsigned int is_inflated : 1;
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最后于 2021-5-31 17:24
被唱过阡陌编辑
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