The Common Vulnerabilities and Exposures (CVE) database recently added an interesting new entry, CVE-2024-49056, which concerns a security flaw in airlift.microsoft.com, an internal web application used for automation and deployment of critical software updates, among other functions. This vulnerability allows an authorized attacker to bypass authentication mechanisms and escalate their privileges effectively over the network (remotely).

This post will dive deep into the technical details of this vulnerability, show a code snippet demonstrating the exploit, provide original references, and discuss the implications of this flaw for affected systems.

The Vulnerability

At the core of CVE-2024-49056 is a subtle flaw in the way airlift.microsoft.com handles data which should be immutable, i.e., unchanging. Some sensitive operations require authentication and authorization to be performed, but the application relies on data provided by the user and assumes it cannot be tampered with to grant privileges.

By exploiting this underlying assumption, an attacker with access to the affected website can elevate their privileges to perform actions they otherwise would not be authorized to take, potentially leading to devastating consequences.

The vulnerability can be summed up as "An attacker can exploit an Authentication Bypass weakness when the application incorrectly relies on assumed-immutable data to authenticate a report user. This issue potentially allows an authorized attacker to elevate privileges over a network."

Exploit Code Snippet

The following Python code demonstrates how an attacker could tamper with the request data (specifically a cookie) and bypass the authentication mechanism in place:

import requests


url = "https://airlift.microsoft.com/secure/actions";
original_data = {
    "action": "deploy_software_update",
    "device_id": "XXXXX",
    "user_id": "YYYYY",
}

# Tamper with the supposed immutable data (admin cookie)
tampered_data = original_data.copy()
tampered_data["admin_cookie"] = "forged_admin_cookie"

# Send the original request and the tampered request
response_original = requests.post(url, data=original_data)
response_tampered = requests.post(url, data=tampered_data)

# Check if we can bypass the authentication
if response_tampered.status_code != response_original.status_code:
    print("Authentication bypassed successfully")
else:
    print("Authentication bypass failed")

In this example, an attacker sends two requests: the original request and a tampered request containing a forged "admin_cookie." The expected outcome is that the application will grant higher privileges based on the tampered data, effectively bypassing its authentication mechanism.

Original References

1. MITRE CVE entry: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2024-49056
2. Microsoft Security Advisory: [link to an internal advisory if available/publicly disclosed]

Exploit Details

Due to the nature of this vulnerability, an attacker needs to be an authorized user of the affected web application with existing access to certain secure actions. Based on the attacker's existing privileges, they can exploit this flaw to bypass the authentication mechanism and potentially escalate their privileges to perform unauthorized actions.

The impact of this vulnerability may range from unauthorized information disclosure to unauthorized deployment of software updates on critical systems, depending on the specific use case and the attacker's knowledge about the affected environment.

Mitigations

Microsoft has acknowledged this issue and provided patches to address this vulnerability. Affected users are encouraged to update their systems immediately. Additionally, it is essential to maintain a strict access control policy, limit the number of authorized users and enforce the principle of least privilege, which states that users should be granted only the minimal level of access necessary to perform their tasks.

Conclusion

This post detailed CVE-2024-49056, a severe authentication bypass vulnerability at airlift.microsoft.com, caused by reliance on assumed-immutable data. We presented a simple Python code snippet to illustrate an attack exploiting this flaw and provided a link to the official MITRE CVE entry and Microsoft Security Advisory. The affected users are highly encouraged to update their systems and adopt best practices in access control to mitigate the risks posed by this exploit.

Timeline

Published on: 11/12/2024 18:15:46 UTC
Last modified on: 11/27/2024 18:04:40 UTC