CVE Vulnerabilities

CVE-2019-11230

Improper Link Resolution Before File Access ('Link Following')

Published: Jul 18, 2019 | Modified: Jul 24, 2019
CVSS 3.x
4.4
MEDIUM
Source:
NVD
CVSS:3.0/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:N
CVSS 2.x
3.6 LOW
AV:L/AC:L/Au:N/C:N/I:P/A:P
RedHat/V2
RedHat/V3
Ubuntu

In Avast Antivirus before 19.4, a local administrator can trick the product into renaming arbitrary files by replacing the LogsUpdate.log file with a symlink. The next time the product attempts to write to the log file, the target of the symlink is renamed. This defect can be exploited to rename a critical product file (e.g., AvastSvc.exe), causing the product to fail to start on the next system restart.

Weakness

The product attempts to access a file based on the filename, but it does not properly prevent that filename from identifying a link or shortcut that resolves to an unintended resource.

Affected Software

Name Vendor Start Version End Version
Antivirus Avast * *

Potential Mitigations

  • Follow the principle of least privilege when assigning access rights to entities in a software system.
  • Denying access to a file can prevent an attacker from replacing that file with a link to a sensitive file. Ensure good compartmentalization in the system to provide protected areas that can be trusted.

References