An independent bug bounty hunter, known as 51l3nc3, has recently discovered a vulnerability in the VAPIX API used in Axis devices as part of the AXIS OS Bug Bounty Program. The issue found specifically affects the uploadoverlayimage.cgi file and enumerates that there is a lack of input validation, resulting in a loophole for an attacker to exploit by uploading files that could potentially block access to create image overlays in the web interface of the Axis device. In simpler terms, this vulnerability could allow an attacker to intrude into the system and hinder the creation of image overlays through the web interface.

In this detailed post, we will provide a comprehensive view of the vulnerability, along with the affected Axis devices, a code snippet demonstrating the flaw, links to original references, and an explanation of how an attacker could exploit this vulnerability.

Affected Axis Devices

Various Axis devices and cameras that utilize the VAPIX API are affected by this vulnerability. A full list of vulnerable Axis devices can be found in the CVE database or the Axis security advisory in the references section below.

Code Snippet

The code snippet below demonstrates the vulnerable portion of the uploadoverlayimage.cgi file, where the input validation has been overlooked:

#include <stdlib.h>
#include <string.h>
#include <unistd.h>

int main(int argc, char **argv)
{
    char user_input[1024];
    char file_name[256];

    printf("Enter the file name to upload as an overlay image: ");
    fgets(user_input, sizeof(user_input), stdin);

    // Insufficient input validation occurs here
    strcpy(file_name, user_input);

    // File upload process with the vulnerable file_name
    upload_overlay_img(file_name);

    return ;
}

In the above code snippet, the strcpy() function is used to copy user-input directly into the file_name variable without any proper input validation or sanitization.

1. AXIS OS Bug Bounty Program: https://www.axis.com/en-us/about-axis/axis-labs/bug-bounty
2. Axis Security Advisory: https://www.axis.com/en-us/support/security-advisory
3. CVE Details: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2024-47261

Exploit Details

Exploiting this vulnerability requires an attacker to know the details of the vulnerable uploadoverlayimage.cgi file and attempt to either upload a malicious file or flood the web interface with multiple files that may cause performance issues. By doing so, they prevent the user from successfully creating image overlays via the web interface. To take advantage of this flaw, the attacker could potentially create a script that repeatedly uploads files to the vulnerable endpoint.

Conclusion

The vulnerability discovered by 51l3nc3 highlights the importance of thorough input validation in software development, especially in the realm of security devices such as Axis cameras. Effective input validation ensures that user inputs are inspected, sanitized, and properly checked prior to using them in the code.

To mitigate this vulnerability, Axis has issued security advisories and is continuously working on implementing patches, updates, and fixes. End-users and system administrators using affected Axis devices are highly recommended to apply the latest firmware updates or patches, as well as maintain best security practices when deploying and configuring such devices.

Timeline

Published on: 04/08/2025 06:15:43 UTC
Last modified on: 04/08/2025 18:13:53 UTC