SharePoint CVE-2024-38094: Why On-Prem SharePoint Stays a Target

Last updated: April 26, 2026

SharePoint Server has produced critical RCE vulnerabilities at a sustained cadence. CVE-2024-38094, disclosed July 2024, allowed authenticated remote code execution via a deserialisation flaw. Exploited within days by ransomware operators against Indian on-prem SharePoint deployments. This article covers the bug, the broader SharePoint vulnerability pattern, and the migration / hardening path that closes the attack surface.

The vulnerability

SharePoint Server’s web component had an insecure deserialisation flaw that allowed an authenticated low-privilege user to send a crafted request that executed arbitrary code on the server. Authenticated meant any user with site access — typically every domain user in a corporate environment.

The exploit chain:

1. Authenticate as any low-privilege user
2. Send a crafted POST to the vulnerable endpoint
3. Insecure deserialisation triggers .NET object instantiation under attacker control
4. Code execution as the SharePoint application pool identity (typically a domain account with broad privilege)

The recent SharePoint CVE roster

Pattern: nearly every year a critical SharePoint CVE. The product surface is large; defender attention typically lower than for Exchange or AD.

Why on-prem SharePoint persists

• Indian government and PSU deployments prefer on-prem for data-residency reasons
• Custom workflows and integrations make migration to SharePoint Online expensive
• Document libraries with regulated content (legal, HR, financial) often kept on-prem
• Hybrid SharePoint — partly on-prem, partly cloud — common configuration

Detection — what to monitor

• IIS access logs for POST requests to _api/Web/... and _layouts/15/... endpoints with anomalous POST sizes or query strings
• Process spawning from w3wp.exe (IIS worker) — cmd.exe, powershell.exe, or .NET-loaded code under unusual circumstances
• SharePoint diagnostic logs for unhandled exceptions in custom or unfamiliar paths
• Application-pool identity activity — outbound network connections, file modifications outside content directories

Microsoft Defender for Endpoint and Defender for Identity have specific SharePoint exploitation detections. Sigma rules from SigmaHQ cover known SharePoint CVE patterns.

Mitigation pattern

1. Patch SharePoint to current cumulative update within 7 days of release. SharePoint patching has historically been months-late at many organisations.
2. Restrict SharePoint admin interfaces to internal networks only. SharePoint Central Administration must not be public-facing.
3. Reduce application-pool identity privileges to minimum.
4. WAF rules between users and SharePoint that block known exploitation patterns.
5. Audit logging enabled and forwarded to SIEM.
6. Plan migration to SharePoint Online for non-residency-constrained content.

The strategic answer

Microsoft has moved most active development to SharePoint Online. On-prem SharePoint is in maintenance mode but receives security patches. For organisations with regulatory or data-residency requirements that prevent cloud migration:

• Aggressive monthly patching
• Network segregation — SharePoint not reachable from general user networks except specific authentication-required paths
• Privileged Access Workstation pattern for SharePoint admins
• Continuous monitoring with EDR + SIEM

Compliance angle

• RBI Cyber Framework — application security and patching SLA explicitly required
• SEBI CSCRF — collaboration platforms with regulated content require enhanced controls
• DPDP §8(5) — known-vulnerable SharePoint in production processing personal data fails reasonable security

The takeaway

SharePoint CVEs are predictable — one to two critical RCEs per year. Migration to SharePoint Online removes the on-prem patching obligation. For organisations that must stay on-prem, monthly patching cadence + network segregation + EDR coverage are non-negotiable. The 2024 CVEs (38094, 38024) showed how quickly ransomware operators weaponise SharePoint vulnerabilities. Patch faster than they can.