CVE-2021-40524 : Exploit Details and Defense Strategies
Discover the impact and mitigation steps for CVE-2021-40524 in Pure-FTPd before 1.0.50. Learn how attackers upload files to cause denial of service.
In Pure-FTPd before 1.0.50, an incorrect max_filesize quota mechanism allows attackers to upload files of unbounded size, leading to denial of service or server hang.
Understanding CVE-2021-40524
This CVE involves an issue in Pure-FTPd versions 1.0.23 through 1.0.49 that enables DoS attacks through file upload.
What is CVE-2021-40524?
- Vulnerability Type: Incorrect max_filesize quota mechanism
- Attack Vector: File upload
- Affected Versions: 1.0.23 through 1.0.49
- Impact: Denial of service or server hang
The Impact of CVE-2021-40524
The vulnerability allows attackers to overrun the max_filesize quota, causing a DoS condition or server unavailability.
Technical Details of CVE-2021-40524
This section covers the technical aspects of the CVE.
Vulnerability Description
- Incorrect max_filesize quota check
- Vulnerable versions: 1.0.23 - 1.0.49
Affected Systems and Versions
- Pure-FTPd versions 1.0.23 through 1.0.49
Exploitation Mechanism
- By uploading files beyond the max_filesize quota
Mitigation and Prevention
Best practices to mitigate and prevent exploitation of CVE-2021-40524.
Immediate Steps to Take
- Upgrade Pure-FTPd to version 1.0.50
- Monitor file uploads for unusually large sizes
Long-Term Security Practices
- Regularly update software and security patches
- Implement file size restrictions and server-side validation
Patching and Updates
- Apply the latest patch provided by Pure-FTPd developers