// For flags

CVE-2021-27241

Avast Premium Security AvastSvc Directory Junction Denial-of-Service Vulnerability

Severity Score

6.1
*CVSS v3.1

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

0
*Multiple Sources

Exploited in Wild

-
*KEV

Decision

-
*SSVC
Descriptions

This vulnerability allows local attackers to delete arbitrary directories on affected installations of Avast Premium Security 20.8.2429 (Build 20.8.5653.561). An attacker must first obtain the ability to execute low-privileged code on the target system in order to exploit this vulnerability. The specific flaw exists within the AvastSvc.exe module. By creating a directory junction, an attacker can abuse the service to delete a directory. An attacker can leverage this vulnerability to create a denial-of-service condition on the system. Was ZDI-CAN-12082.

Esta vulnerabilidad permite a atacantes locales eliminar directorios arbitrarios en las instalaciones afectadas de Avast Premium Security versión 20.8.2429 (Build 20.8.5653.561). Un atacante primero debe obtener la capacidad de ejecutar código poco privilegiado en el sistema de destino para explotar esta vulnerabilidad. El fallo específico se presenta dentro del módulo AvastSvc.exe. Al crear una unión de directorio, un atacante puede abusar del servicio para eliminar un directorio. Un atacante puede aprovechar esta vulnerabilidad para crear una condición de denegación de servicio en el sistema. Era ZDI-CAN-12082

This vulnerability allows local attackers to delete arbitrary directories on affected installations of Avast Premium Security. An attacker must first obtain the ability to execute low-privileged code on the target system in order to exploit this vulnerability.
The specific flaw exists within the AvastSvc.exe module. By creating a directory junction, an attacker can abuse the service to delete a directory. An attacker can leverage this vulnerability to create a denial-of-service condition on the system.

*Credits: Abdelhamid Naceri
CVSS Scores
Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
High
Attack Vector
Local
Attack Complexity
Low
Authentication
None
Confidentiality
None
Integrity
Partial
Availability
Partial
* Common Vulnerability Scoring System
SSVC
  • Decision:-
Exploitation
-
Automatable
-
Tech. Impact
-
* Organization's Worst-case Scenario
Timeline
  • 2021-02-16 CVE Reserved
  • 2021-02-24 CVE Published
  • 2023-03-08 EPSS Updated
  • 2024-08-03 CVE Updated
  • ---------- Exploited in Wild
  • ---------- KEV Due Date
  • ---------- First Exploit
CWE
  • CWE-59: Improper Link Resolution Before File Access ('Link Following')
CAPEC
References (1)
URL Date SRC
URL Date SRC
URL Date SRC
Affected Vendors, Products, and Versions
Vendor Product Version Other Status
Vendor Product Version Other Status <-- --> Vendor Product Version Other Status
Avast
Search vendor "Avast"
Premium Security
Search vendor "Avast" for product "Premium Security"
20.8.2429
Search vendor "Avast" for product "Premium Security" and version "20.8.2429"
-
Affected