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executable file 77 lines (65 sloc) 2.29 KB
#!/usr/bin/python2
#
# Use Auxiliary Vector and `/proc/<pid>/mem` syscall to dump the canary
# of a PID.
#
# Execute with:
# $ ./read_canary_from_pid.py <PID>
#
# @_hugsy_
#
# Copyright (c) 2017 elttam
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in all
# copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.
from __future__ import print_function
import sys, struct, platform
AT_RANDOM = 25
if platform.architecture()[0]=='64bit':
L = 8
F = "<Q"
else:
L = 4
F = "<I"
def get_at_random_address(pid):
res = None
with open("/proc/{}/auxv".format(pid)) as f:
while True:
k = struct.unpack(F, f.read(L))[0]
if k<=0:
break
v = struct.unpack(F, f.read(L))[0]
if k==AT_RANDOM:
res = v
break
return res
def read_memory(pid, addr, n):
with open("/proc/{}/mem".format(pid)) as f:
f.seek(addr)
return f.read(n)
if __name__ == "__main__":
if len(sys.argv)!=2 or not sys.argv[1].isdigit():
print("[-] Syntax: {} <PID>".format(sys.argv[0]))
sys.exit(1)
pid = int(sys.argv[1])
addr = get_at_random_address(pid)
print("[+] at_random={:#x}".format(addr))
canary = read_memory(pid, addr, L)
canary = struct.unpack(F, canary)[0]
canary&= ~0xff
print("[+] canary for pid={:d} is {:#x}".format(pid, canary))