The recent attacks on enterprises that hosted their own Microsoft SharePoint servers highlight the risks inherent in modern collaborative environments. In this run of breaches, more than 400 organizations worldwide—including critical infrastructure, government agencies, and research institutions—found themselves compromised as threat actors exploited a largely unknown flaw.
Enterprises will only increase their dependence on collaboration environments like Microsoft SharePoint. Market analyst firm Grand View Research projects the enterprise collaboration tools market, encompassing platforms like SharePoint for file sharing, communication, project management, and unified workflows, to grow from about $61 billion in 2025 to $107 billion by 2030. These platforms have quickly become prime targets for cyberattacks.
“Collaboration platforms are uniquely attractive to threat actors because they hold large amounts of an enterprise’s most sensitive data in one place,” said Adam Ennamli, chief risk officer, General Bank of Canada. And collaborative environments not only require broad access and frequent data sharing but deep integration with numerous additional enterprise systems.
It’s their necessity for such accessibility that makes secure configuration especially challenging—and when a zero-day vulnerability emerges, the damage can be swift. For instance, the attackers that exploited the “ToolShell” bypassed authentication controls, implanted persistent backdoors, and leveraged stolen credentials to move laterally across victim networks, sometimes undetected for weeks.
Those organizations that chose to run their SharePoint servers on-premises for increased security found themselves with quite the wake-up call. The ToolShell vulnerability affects on-premises SharePoint servers only, including SharePoint Server Subscription Edition, SharePoint Server 2019, and SharePoint Server 2016. SharePoint Online in Microsoft 365 environments are not impacted by this vulnerability.
The incident may prompt some reconsideration of their on-premises strategy. “Organizations may want to re-evaluate their appetite for managing on-premises workloads and further consider cloud-based solutions. These types of incidents may serve to trigger this re-evaluation. In addition to security benefits, migrating to the cloud can offer cost savings in overhead and ongoing management of on-premises assets and workloads,” said Todd Thorsen, CISO at CrashPlan.
“For SharePoint specifically, and other IT tools, like Jira, we transitioned to a full SaaS and managed model,” Ahmed Fessi, chief transformation and information officer at software provider Medius, said. “This and overhead of managing vulnerabilities directly, but also vendors (like Microsoft or Atlassian), who apply patches more recurrently than if we had the deployment ourselves,” Fessi added.
The ToolShell SharePoint incident proved painful. Even after Microsoft’s emergency patches, adversaries found ways to bypass what turned out to be incomplete fixes, and they forced the subsequent release of additional security updates. More alarming: the attackers who had already compromised systems stole ASP.NET machine keys. This enabled them to maintain persistent access—even after organizations believed they had secured the flaw.
Serhii Melnyk, cyber threat intelligence analyst at Trustwave, advises enterprise security teams to take a closer look at the defenses around such platforms. “To better protect collaboration platforms like Microsoft SharePoint and reduce exposure to zero-day risks over time, organizations should adopt a multi-layered security strategy. This includes implementing regular and timely security patching to address known vulnerabilities and prevent exploitation,” Melnyk said.
Beyond a frantic race to patch, what steps can organizations take to mitigate the risks of such situations going forward? The experts we spoke with advised:
Consider a zero-trust, or at least an identity-first, architecture
Security experts advocated for zero trust. The never trust, always verify zero trust mindset requires continuous authentication, conditional access policies informed by user context and risk level, and assigning only the minimum permissions necessary for each person’s or non-human identity’s role. And every access request must be scrutinized, no matter where it originates.
This also includes segmenting networks, especially around sensitive collaborative infrastructure, which limits potential lateral movement after a breach. By establishing granular controls, organizations can contain breaches to isolated segments, minimizing widespread impact and buying more detection and remediation time. For on-premises SharePoint servers, it is recommended to segment these servers into secure zones with restricted access, treating them as a potential initial attack vector, Melnyk advised.
“You definitely must shift from perimeter-based to identity-based security,” added General Bank of Canada’s Ennamli.
Cloud-Specific Security Controls
For cloud and hybrid platforms, enable multi-factor authentication (MFA) for all users, use role-based access and regular permissions audits, deploy data loss prevention (DLP) and information rights management to prevent leaks, and complement native platform security with third-party threat detection integrated via APIs.
Behavioral Analytics and Threat Intelligence
Go beyond signatures and hardening. Effective threat detection depends on understanding normal user and system behavior to spot anomalies—unusual logins, data downloads, or privilege escalations indicate possible compromise even when the initial exploit is unknown. Integrating AI-driven behavioral analytics and subscribing to live threat intelligence feeds enables enterprises to spot emerging threats earlier and tailor responses to actual attack patterns rather than relying on yesterday’s news.
Continuous Threat Exposure Management
Rather than relying solely on periodic vulnerability scans, enterprises must adopt continuous threat exposure management (CTEM): frequent asset inventorying, breach and attack simulations, attack path mapping, and risk-prioritized remediation. The focus is on reducing the exploitable exposure, not just patching.
“We have subscribed to a service that sends us all newly discovered vulnerabilities, and then we have an automation that checks against all our infrastructure and notifies our security team in case of any match, in which case, the incident response team will ensure a fix is applied as soon as possible, and forensics are performed to check if this was exploited,” said Fessi.
Given the state of software security, enterprises must develop and regularly test incident response plans tailored to zero-day and collaborative environment attacks. This includes monitoring, isolation procedures, and tested backups. Plans for recovery from “permanent backdoors,” like those implanted during the ToolShell campaign, may even require re-keying encryption mechanisms and wholesale system rebuilds.
For CISOs and enterprise security teams, adopting a “prepare, detect, contain, and recover” mindset—rooted in Zero Trust and behavioral defense—may spell the difference between a headline-making breach and a contained incident. In tomorrow’s collaborative workplace, such vigilance is not just prudent; it’s essential for survival.
