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| 1 | +// |
| 2 | +// IPAPatchBypassAntiDebugging.m |
| 3 | +// IPAPatch |
| 4 | +// |
| 5 | +// Created by wutian on 2017/3/23. |
| 6 | +// Copyright © 2017年 Weibo. All rights reserved. |
| 7 | +// |
| 8 | + |
| 9 | +#import "IPAPatchBypassAntiDebugging.h" |
| 10 | +#import "fishhook.h" |
| 11 | +#import <dlfcn.h> |
| 12 | +#import <sys/sysctl.h> |
| 13 | + |
| 14 | +#define TESTS_BYPASS 0 |
| 15 | + |
| 16 | +// Sources: |
| 17 | +// https://www.coredump.gr/articles/ios-anti-debugging-protections-part-1/ |
| 18 | +// https://www.coredump.gr/articles/ios-anti-debugging-protections-part-2/ |
| 19 | +// https://www.theiphonewiki.com/wiki/Bugging_Debuggers |
| 20 | + |
| 21 | +// Bypassing PT_DENY_ATTACH technique |
| 22 | + |
| 23 | +static void * (*original_dlsym)(void *, const char *); |
| 24 | + |
| 25 | +int fake_ptrace(int _request, pid_t _pid, caddr_t _addr, int _data) |
| 26 | +{ |
| 27 | + return 0; |
| 28 | +} |
| 29 | + |
| 30 | +void * hooked_dlsym(void * __handle, const char * __symbol) |
| 31 | +{ |
| 32 | + if (strcmp(__symbol, "ptrace") == 0) { |
| 33 | + return &fake_ptrace; |
| 34 | + } |
| 35 | + |
| 36 | + return original_dlsym(__handle, __symbol); |
| 37 | +} |
| 38 | + |
| 39 | +static void disable_pt_deny_attach() |
| 40 | +{ |
| 41 | + original_dlsym = dlsym(RTLD_DEFAULT, "dlsym"); |
| 42 | + rebind_symbols((struct rebinding[1]){{"dlsym", hooked_dlsym}}, 1); |
| 43 | +} |
| 44 | + |
| 45 | +// Bypassing sysctl debugger checking technique |
| 46 | + |
| 47 | +static int (*original_sysctl)(int *, u_int, void *, size_t *, void *, size_t); |
| 48 | + |
| 49 | +typedef struct kinfo_proc ipa_kinfo_proc; |
| 50 | + |
| 51 | +int hooked_sysctl(int * arg0, u_int arg1, void * arg2, size_t * arg3, void * arg4, size_t arg5) |
| 52 | +{ |
| 53 | + bool modify_needed = arg1 == 4 && arg0[0] == CTL_KERN && arg0[1] == KERN_PROC && arg0[2] == KERN_PROC_PID && arg2 && arg3 && (*arg3 >= sizeof(struct kinfo_proc)); |
| 54 | + |
| 55 | + int ret = original_sysctl(arg0, arg1, arg2, arg3, arg4, arg5); |
| 56 | + |
| 57 | + if (modify_needed) { |
| 58 | + ipa_kinfo_proc * pointer = arg2; |
| 59 | + ipa_kinfo_proc info = *pointer; |
| 60 | + info.kp_proc.p_flag = 0; |
| 61 | + *pointer = info; |
| 62 | + } |
| 63 | + |
| 64 | + return ret; |
| 65 | +} |
| 66 | + |
| 67 | +static void disable_sysctl_debugger_checking() |
| 68 | +{ |
| 69 | + original_sysctl = dlsym(RTLD_DEFAULT, "sysctl"); |
| 70 | + rebind_symbols((struct rebinding[1]){{"sysctl", hooked_sysctl}}, 1); |
| 71 | +} |
| 72 | + |
| 73 | +#if TESTS_BYPASS |
| 74 | +// Tests |
| 75 | +static void test_aniti_debugger(); |
| 76 | +#endif |
| 77 | + |
| 78 | +@implementation IPAPatchBypassAntiDebugging |
| 79 | + |
| 80 | ++ (void)load |
| 81 | +{ |
| 82 | + disable_pt_deny_attach(); |
| 83 | + disable_sysctl_debugger_checking(); |
| 84 | + |
| 85 | +#if TESTS_BYPASS |
| 86 | + test_aniti_debugger(); |
| 87 | +#endif |
| 88 | +} |
| 89 | + |
| 90 | +@end |
| 91 | + |
| 92 | +#if TESTS_BYPASS |
| 93 | + |
| 94 | +typedef int (*ptrace_ptr_t)(int _request, pid_t _pid, caddr_t _addr, int _data); |
| 95 | + |
| 96 | +#if !defined(PT_DENY_ATTACH) |
| 97 | +#define PT_DENY_ATTACH 31 |
| 98 | +#endif |
| 99 | + |
| 100 | +static void test_aniti_debugger() |
| 101 | +{ |
| 102 | + void* handle = dlopen(0, RTLD_GLOBAL | RTLD_NOW); |
| 103 | + ptrace_ptr_t ptrace_ptr = dlsym(handle, "ptrace"); |
| 104 | + ptrace_ptr(PT_DENY_ATTACH, 0, 0, 0); |
| 105 | + dlclose(handle); |
| 106 | + |
| 107 | + int name[4]; |
| 108 | + struct kinfo_proc info; |
| 109 | + size_t info_size = sizeof(info); |
| 110 | + |
| 111 | + info.kp_proc.p_flag = 0; |
| 112 | + |
| 113 | + name[0] = CTL_KERN; |
| 114 | + name[1] = KERN_PROC; |
| 115 | + name[2] = KERN_PROC_PID; |
| 116 | + name[3] = getpid(); |
| 117 | + |
| 118 | + if (sysctl(name, 4, &info, &info_size, NULL, 0) == -1) { |
| 119 | + perror("sysctl"); |
| 120 | + exit(-1); |
| 121 | + } |
| 122 | + bool debugging = ((info.kp_proc.p_flag & P_TRACED) != 0); |
| 123 | + |
| 124 | + NSCAssert(!debugging, @"Debug checking should be disabled"); |
| 125 | +} |
| 126 | + |
| 127 | +#endif // TESTS_BYPASS |
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