Exploit matérialisé

CVE-2019-1476

HIGH

1 exploit(s) public(s) pour cette CVE, 1 matérialisé(s) avec leur code.

À des fins de recherche défensive uniquement. Ne testez que sur des systèmes que vous possédez ou pour lesquels vous détenez une autorisation écrite. L'accès non autorisé est illégal.

ExploitDB dos windows

Source

AppXSvc 17763 - Arbitrary File Overwrite (DoS)

Par Gabor Seljan

Comment tester cet exploit

Déni de service : envoie une entrée malformée pour crasher le service. À tester en VM isolée, l'effet est destructif.

Code txt

# Exploit Title: AppXSvc 17763 - Arbitrary File Overwrite (DoS)
# Date: 2019-10-28
# Exploit Author: Gabor Seljan
# Vendor Homepage: https://www.microsoft.com/
# Version: 17763.1.amd64fre.rs5_release.180914-1434
# Tested on: Windows 10 Version 1809 for x64-based Systems
# CVE: CVE-2019-1476

# Summary:
# AppXSvc improperly handles file hard links resulting in a low privileged user
# being able to overwrite an arbitrary file leading to elevation of privilege.

# Description:

# An elevation of privilege vulnerability exists when the AppX Deployment Server
# (AppXSvc) improperly handles file hard links. While researching CVE-2019-0841
# originally reported by Nabeel Ahmed, I have found that AppXSvc can be forced
# to overwrite an arbitrary file by deleting all registry data files before
# creating the file hard link. As Nabeel Ahmed described in his write-up of
# CVE-2019-0841, if the settings.dat file is corrupted it will be replaced with
# the original settings.dat template. However, additional settings.dat.LOG1 and
# settings.dat.LOG2 files are also created during the initialization process.
# Substituting the settings.dat.LOG1 or the settings.dat.LOG2 file with a hard
# link allows a low privileged user to overwrite an arbitrary file with registry
# data or just simply empty it, respectively. A low privileged user could exploit
# this vulnerability to cause denial of service by overwriting critical system
# files.

Steps to reproduce:
1. Terminate Paint 3D processes.
2. Delete settings.* files in Microsoft.MSPaint_8wekyb3d8bbwe\Settings folder.
3. Create a hard link from settings.dat.LOG1 to C:\Windows\win.ini.
4. Execute the start ms-paint: command to run Paint 3D.
5. Terminate Paint 3D processes.

Expected result:
It isn't possible to overwrite a file not writable by a low privileged user.

Observed result:
C:\Windows\win.ini file is overwritten with registry data.

References:
https://github.com/sgabe/CVE-2019-1476
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2019-1476
https://krbtgt.pw/dacl-permissions-overwrite-privilege-escalation-cve-2019-0841