InstantHMI 6.1 – Local Privilege Escalation
Title: InstantHMI - EoP: User to ADMIN CWE Class: CWE-276: Incorrect Default Permissions Date: 01/06/2016 Vendor: Software Horizons Product: InstantHMI Version: 6.1 Download link: http://www.instanthmi.com/ihmisoftware.htm Tested on: Windows 7 x86, fully patched Release mode: no bugbounty program, public release Installer Name: IHMI61-PCInstall-Unicode.exe MD5: ee3ca3181c51387d89de19e89aea0b31 SHA1: c3f1929093a3bc28f4f8fdd9cb38b1455d7f0d6f - 1. Introduction: - During a standard installation (default option) the installer automatically creates a folder named "IHMI-6" in the root drive. No other location can be specified during standard installation. As this folder receives default permissions AUTHENTICATED USERS are given the WRITE permission. Because of this they can replace binaries or plant malicious DLLs to obtain elevated, administrative level, privileges. - 2. Technical Details/PoC: - A. Obtain and execute the installer. B. Observe there is no prompt for the installation location. C. Review permissions under the Explorer Security tab or run icacls.exe Example: IHMI-6 BUILTIN\Administrators:(I)(F) BUILTIN\Administrators:(I)(OI)(CI)(IO)(F) NT AUTHORITY\SYSTEM:(I)(F) NT AUTHORITY\SYSTEM:(I)(OI)(CI)(IO)(F) BUILTIN\Users:(I)(OI)(CI)(RX) NT AUTHORITY\Authenticated Users:(I)(M) NT AUTHORITY\Authenticated Users:(I)(OI)(CI)(IO)(M) Successfully processed 1 files; Failed processing 0 files D. Change the main executable: InstantHMI.exe with a malicious copy. E. Once executed by an administrator our code will run under administrator level privileges. - 3. Mitigation: - A. Install under "c:\program files" or "C:\Program Files (x86)" B. set appropriate permissions on the application folder. - 4. Author: - sh4d0wman |