Sudo 1.8.14 (RHEL 5/6/7 / Ubuntu) – ‘Sudoedit’ Unauthorized Privilege Escalation

• Exploit Database
• 15 阅读

• 作者： daniel svartman
  日期： 2015-07-28
• 类别：

  • local
  平台：

  • linux
• 来源：https://www.exploit-db.com/exploits/37710/

• # Exploit Title: sudo -e - a.k.a. sudoedit -unauthorized privilege escalation
  # Date: 07-23-2015
  # Exploit Author: Daniel Svartman
  # Version: Sudo <=1.8.14
  # Tested on: RHEL 5/6/7 and Ubuntu (all versions)
  # CVE: CVE-2015-5602.
  
  Hello,
  
  I found a security bug in sudo (checked in the latest versions of sudo
  running on RHEL and ubuntu) when a user is granted with root access to
  modify a particular file that could be located in a subset of directories.
  
  It seems that sudoedit does not check the full path if a wildcard is used
  twice (e.g. /home/*/*/file.txt), allowing a malicious user to replace the
  file.txt real file with a symbolic link to a different location (e.g.
  /etc/shadow).
  
  I was able to perform such redirect and retrieve the data from the
  /etc/shadow file.
  
  In order for you to replicate this, you should configure the following line
  in your /etc/sudoers file:
  
  <user_to_grant_priv> ALL=(root) NOPASSWD: sudoedit /home/*/*/test.txt
  
  Then, logged as that user, create a subdirectory within its home folder
  (e.g. /home/<user_to_grant_priv>/newdir) and later create a symbolic link
  inside the new folder named test.txt pointing to /etc/shadow.
  
  When you run sudoedit /home/<user_to_grant_priv>/newdir/test.txt you will
  be allowed to access the /etc/shadow even if have not been granted with
  such access in the sudoers file.
  
  I checked this against fixed directories and files (not using a wildcard)
  and it does work with symbolic links created under the /home folder.