CVE-2022-35823: Microsoft SharePoint Server RCE Flaw

CVE-2022-35823 Overview

CVE-2022-35823 is a Remote Code Execution (RCE) vulnerability affecting Microsoft SharePoint Server products. This vulnerability allows authenticated attackers with low privileges to execute arbitrary code on affected SharePoint installations via a network-based attack vector. The flaw requires no user interaction to exploit, making it particularly dangerous in enterprise environments where SharePoint serves as a critical collaboration platform.

Critical Impact

Authenticated attackers can achieve remote code execution on vulnerable SharePoint servers, potentially leading to complete system compromise, data theft, lateral movement within enterprise networks, and persistent access to sensitive corporate information.

Affected Products

• Microsoft SharePoint Enterprise Server 2013 SP1
• Microsoft SharePoint Enterprise Server 2016
• Microsoft SharePoint Foundation 2013 SP1
• Microsoft SharePoint Server 2019
• Microsoft SharePoint Server Subscription Edition

Discovery Timeline

• 2022-09-13 - CVE-2022-35823 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2022-35823

Vulnerability Analysis

This Remote Code Execution vulnerability in Microsoft SharePoint allows an authenticated attacker with network access to execute arbitrary code in the context of the SharePoint application pool identity. The vulnerability exists due to improper handling of certain requests, enabling attackers who have obtained valid credentials to the SharePoint environment to escalate their access significantly.

The exploitation scenario is particularly concerning because it can be achieved with minimal privileges. An attacker only needs basic authenticated access to a SharePoint site to potentially leverage this vulnerability. Once exploited, the attacker could execute code with the permissions of the SharePoint service account, which typically has elevated privileges on the system and potentially access to sensitive business data stored within SharePoint.

Root Cause

While Microsoft has not disclosed the specific technical root cause details for this vulnerability (classified as NVD-CWE-noinfo), the Remote Code Execution classification combined with the network attack vector and low privilege requirements suggests the vulnerability likely stems from improper input validation or insecure deserialization in SharePoint's request processing pipeline. SharePoint's complex architecture includes numerous components that handle serialized data and process user-supplied content, creating potential attack surfaces for RCE vulnerabilities.

Attack Vector

The attack vector for CVE-2022-35823 is network-based, requiring the attacker to have authenticated access to the SharePoint server. The exploitation flow would typically involve:

1. The attacker establishes a valid authenticated session to the target SharePoint environment with minimal privileges
2. The attacker crafts a malicious request designed to exploit the vulnerability in SharePoint's processing logic
3. The malicious request is sent to the vulnerable SharePoint endpoint
4. Upon processing, the server executes the attacker's arbitrary code in the context of the SharePoint application pool

This vulnerability does not require user interaction, meaning an attacker can trigger exploitation without any additional action from administrators or end users. The scope is unchanged, indicating the vulnerable component and impacted component are the same.

Detection Methods for CVE-2022-35823

Indicators of Compromise

• Unusual process spawning from SharePoint application pool processes (w3wp.exe) such as cmd.exe, powershell.exe, or other unexpected child processes
• Anomalous network connections originating from SharePoint servers to external or unexpected internal destinations
• Unexpected file creation or modification in SharePoint installation directories or web application folders
• Authentication anomalies showing suspicious login patterns followed by unusual SharePoint API calls

Detection Strategies

• Implement application-level logging for SharePoint to capture detailed request information, focusing on unusual parameter patterns or payload sizes
• Deploy endpoint detection and response (EDR) solutions like SentinelOne to monitor SharePoint server processes for behavioral anomalies indicative of code execution attacks
• Configure web application firewall (WAF) rules to detect and block malicious request patterns targeting SharePoint endpoints
• Enable Windows Security event logging to capture process creation events (Event ID 4688) with command-line auditing on SharePoint servers

Monitoring Recommendations

• Monitor SharePoint ULS logs for error patterns or exceptions that may indicate exploitation attempts
• Implement real-time alerting for process execution anomalies on SharePoint servers through SentinelOne's behavioral AI engine
• Track failed and successful authentication attempts to SharePoint to identify potential credential abuse preceding exploitation
• Review IIS logs regularly for unusual request patterns, particularly targeting SharePoint-specific virtual directories and APIs

How to Mitigate CVE-2022-35823

Immediate Actions Required

• Apply the Microsoft security update for CVE-2022-35823 immediately to all affected SharePoint installations
• Audit SharePoint user accounts and permissions, removing unnecessary access and enforcing least privilege principles
• Enable enhanced monitoring on SharePoint servers using SentinelOne or equivalent EDR solutions
• Review network segmentation to ensure SharePoint servers are properly isolated and access is restricted to authorized users and systems

Patch Information

Microsoft has released security updates to address this vulnerability as part of their September 2022 Patch Tuesday release. Administrators should obtain the appropriate patches from the Microsoft Security Response Center update guide for their specific SharePoint version. The patches address the underlying vulnerability by correcting how SharePoint handles certain requests.

Affected versions and their corresponding patches:

• SharePoint Server Subscription Edition
• SharePoint Server 2019
• SharePoint Enterprise Server 2016
• SharePoint Enterprise Server 2013 SP1
• SharePoint Foundation 2013 SP1

Organizations should test patches in a non-production environment before deploying to production SharePoint farms.

Workarounds

• Restrict network access to SharePoint servers by implementing firewall rules that limit connectivity to only required users and systems
• Implement multi-factor authentication (MFA) for SharePoint access to reduce the risk of credential compromise that could enable exploitation
• Consider temporarily restricting anonymous access and enforcing stricter authentication requirements until patches can be applied
• Deploy SentinelOne on SharePoint servers to provide real-time protection against exploitation attempts through behavioral detection capabilities

# Example: Review SharePoint application pool processes for suspicious activity
# Run on SharePoint server to identify unusual child processes
Get-WmiObject Win32_Process | Where-Object {$_.ParentProcessId -eq (Get-Process w3wp | Select-Object -First 1).Id} | Select-Object Name, CommandLine, ProcessId