The phrase “exploited in the wild” instills a unique sense of dread in security practitioners because it signifies that the clock didn’t just start ticking—it began days, weeks, or even months ago, and the alarm is only now sounding. In these critical moments, the immediate and overriding priority shifts to two fundamental questions: what is the extent of the organization’s exposure, and has a compromise already occurred? The situation is exemplified by the research conducted in July 2025 on a previously unknown zero-day vulnerability in Microsoft SharePoint, cataloged as CVE-2025-53770. This flaw permitted attackers to install a persistent backdoor on on-premises servers, steal system security keys, and achieve a full compromise of the machine. This incident underscored the absolute necessity of speed and decisive action in threat identification and remediation. As sophisticated criminal syndicates continue to refine their tooling and leverage undisclosed vulnerabilities for initial access, the pressure on defenders to evolve their response strategies has never been more intense, demanding a shift from reactive measures to proactive threat hunting and validation.
1. Assess Your Vulnerability
The initial task following the publication of a security advisory is to determine whether any organizational assets are potentially exposed to the identified threat. In previous years, a simple vendor claim of exploitation might have been sufficient to trigger a response, but the precedent set over the past several years has demonstrated that relying solely on a vendor advisory for “exploited-in-the-wild” status is an unwise and potentially dangerous strategy. Far too frequently, these advisories or confirmations of active exploitation reach security teams too late or lack the necessary context to prioritize an effective response. A modern, robust remediation program should therefore be built on a foundation of multiple trusted sources, including CISA’s Known Exploited Vulnerabilities (KEV) catalog, reputable third-party security publications, and independent vulnerability researchers. This multi-source approach provides the comprehensive insight needed to address senior management’s most pressing question: “Are we exposed?” Answering this question swiftly and accurately is a non-negotiable requirement that demands immediate attention.
While it may sound straightforward on the surface, professionals who manage vulnerability programs understand that this is precisely where claims of commoditized security solutions are often overstated and fall short. Determining true exposure requires comprehensive content coverage and, in many cases, sophisticated vulnerability validation to confirm whether assets are genuinely susceptible to the reported risk. In situations where additional evidence is required to justify and drive the remediation effort, further validation may become necessary. This can involve leveraging open-source penetration testing tools, such as the Metasploit Framework, which can provide definitive proof of vulnerability. In some high-stakes scenarios, employing such tools may not just be a best practice but an essential component of the incident response process, providing the concrete data needed to escalate the issue and secure the resources for immediate patching or mitigation.
2. Investigate for Compromise
Once the scope of exposure has been determined, the investigation must immediately pivot to the next critical question: has the organization already been compromised? Depending on the nature of the threat, the adversary may have possessed the zero-day exploit for an extended period—potentially days, weeks, or even months. This means they could already be deep within the network, possibly at the final stage of the kill chain and actively exfiltrating sensitive data. The primary focus of this phase is twofold: first, to determine precisely what has been accessed or stolen, and second, to identify and eradicate any persistence mechanisms, such as additional backdoors, that the attacker may have established to ensure their continued access. Many organizations will activate their incident response (IR) retainers at this point to conduct a thorough assessment of the compromise’s extent. At a minimum, an internal team should perform a preliminary threat hunt for known indicators of compromise (IoCs) before formally engaging external IR experts.
Success in this phase is critically dependent on the quality of the intelligence used. Simply downloading generic IoC lists from social media or unvetted sources is a recipe for disaster, as it will inevitably generate a high volume of false positives, obscure the real threat, and likely lead to inaccurate conclusions. Accurate, high-fidelity intelligence is paramount. A cornerstone of an effective initial assessment is ensuring that the threat intelligence incorporates decay scoring to validate the current relevance of command-and-control (C2) infrastructure. For many security teams, the term “threat hunt” often translates to little more than a log search across external gateways. If traffic is observed communicating with known malicious domains or IP addresses, an assumption of compromise may be made, triggering a more comprehensive assessment. However, if the foundation of this entire exercise is outdated intelligence drawn from security research that equates publishing lengthy lists of IoCs with expertise, then the entire process becomes a futile and resource-draining endeavor.
3. Execute Your Response Plan
The specific approach taken at this stage will be dictated entirely by the findings of the preceding exposure and compromise assessments. There is no universal, default playbook that applies to every incident; however, what is indispensable is a well-established and clearly defined decision framework that governs how the organization reacts to different threat scenarios. For instance, in some situations, an organization may discover that a threat actor has been present within its environment for years. In such a case, the only viable path to identifying all hidden backdoors might be to carefully monitor the threat actor’s activity within the environment rather than immediately expelling them. Conversely, in other cases, particularly if ransomware has not yet been deployed, the top priority is to expel the actor as quickly as possible to prevent further damage and data encryption. The chosen strategy must align with the organization’s risk tolerance and the specific context of the breach, balancing the need for complete threat eradication with the imperative to minimize business disruption.
Regardless of the chosen containment strategy, analysts must conduct a final, exhaustive check for any signs of persistence that may have evaded initial detection sweeps. Clever attackers often leave behind multiple footholds to ensure their access remains even if one backdoor is discovered and closed. During the response to the SharePoint exploit, for example, a key tactic was to hunt for known behaviors associated with the attacker’s “ToolShell” to ensure no lingering access points were left behind. This meticulous final validation is critical to truly closing the incident and preventing a swift reinfection. Once the threat is contained and eradicated, the process is far from over. The work transitions to communication, clarity, and post-incident validation, ensuring that all stakeholders are informed and that the organization learns from the event to strengthen its defenses against future attacks. This structured approach, guided by a pre-defined framework, is what separates a chaotic, reactive scramble from a controlled, professional incident response.
4. Manage Recovery and Communication
With the containment and remediation phases complete, the security team’s work is not yet finished; the focus must now pivot to communication, clarity, and validation. A comprehensive and detailed incident report is an essential artifact of the recovery process. This document should meticulously detail a forensic timeline of events from initial intrusion to final remediation, present a confirmed root cause analysis, and list all remediation actions that were taken. Crucially, the report must also provide a clear and unambiguous account of what did and did not occur during the incident, specifically addressing critical questions around data loss, lateral movement within the network, and the establishment of persistence mechanisms. Clear, concise, and timely reporting not only builds confidence among stakeholders and provides a sense of closure but also enables the security team to conduct a thorough post-mortem analysis of its response. This review is vital for recognizing successes and, more importantly, for highlighting areas where processes or technologies need improvement.
This post-incident period presents a critical window of opportunity to address underlying security weaknesses. It is imperative to ensure that senior management fully understands any systemic gaps that were identified during the response. While the phrase “never waste a good security incident” may sound cliché, it holds a fundamental truth: if improvements are needed, this is the most opportune time to secure the necessary investment and executive support. If a sophisticated threat actor has already successfully compromised the environment and no meaningful changes are subsequently made to the security posture, a repeat incident is not just possible but highly likely. This is not a statement intended to spread fear, but rather a pragmatic acknowledgment of the current threat landscape. Organized criminal groups are continuously advancing their capabilities, equipping themselves with increasingly potent tooling and techniques that can bypass outdated or incomplete security controls.
The Critical Role of Curated Intelligence
Ultimately, the success of a security team had depended on its ability to spot subtle anomalies in system and network processes, filtering out the overwhelming noise of daily alerts to assemble a clear and accurate picture of a potential threat. It was in this context that curated threat intelligence became absolutely critical to an effective defense. Curated threat intelligence referred to security information that had been carefully selected, thoroughly validated, and placed directly into the context of an organization’s unique technological environment, as opposed to the raw, high-volume data feeds that often overwhelmed security operations. Instead of inundating teams with thousands of undifferentiated indicators or alerts, context-driven intelligence focused their attention on what was relevant, credible, and, most importantly, actionable for a given situation. This strategic approach had allowed suspicious activity to be identified and verified much earlier in the attack lifecycle, significantly reducing an attacker’s window of opportunity before they were able to escalate their privileges or achieve their objectives. The investment in intelligence that was validated, relevant, and tailored to the specific environment had ensured that the security team was not chasing noise but was instead concentrating its finite resources on the threats that truly mattered.
