Horizon Alert
Summary of the vulnerability and why it matters
This vulnerability in Microsoft Office SharePoint involves improper handling of web page inputs, which an authenticated attacker could exploit to perform spoofing attacks over a network. The primary concern is to confirm if SharePoint Server, a commonly internet-facing application, is deployed in your environment and assess potential exposure.
- Input handling flaw allows attacker spoofing.
- SharePoint is often internet-facing.
- Confirm relevance and exposure.
Attack Path
How an attacker could exploit the issue
An authorized attacker can leverage this vulnerability by tricking a SharePoint user into visiting a malicious link, leading to spoofing. The attacker does not need to exploit the vulnerability directly but rather relies on the user's interaction to trigger the malicious code within the web page generation process. This could allow the attacker to impersonate the user, potentially leading to further malicious actions.
- Requires an authenticated user.
- Triggered by user interaction with a crafted link.
- Risk of user impersonation and spoofing.
Live Threat
Current exploitation, exposure, and threat context
This vulnerability could allow an authenticated attacker to conduct spoofing attacks when a user views a specially crafted web page. This may impact service integrity and lead to unauthorized actions when supported by the advisory.
- System data could be at risk.
- Attacker could spoof content.
- Service integrity may be compromised.
Operational Fix
Recommended remediation, mitigation, and detection steps
This critical cross-site scripting vulnerability in Microsoft SharePoint Server requires immediate attention from teams responsible for application and infrastructure security. The first practical step is to locate all instances of SharePoint Server within your environment, determine their exposure, and identify the accountable system owner. Once confirmed, a risk-based remediation plan should be developed, potentially involving vendor coordination and maintenance window scheduling.
- Application and Infrastructure owners should prioritize this.
- Verify SharePoint Server exposure and reachability.
- Plan remediation based on identified risk.
