Think your office printer is harmless? Think again.
Beneath its routine hum lies a legacy service that attackers continue to target—and it still lurks in many corporate environments.
In 2025, Print Spooler vulnerabilities continue to appear in red-team engagements and real-world attacks. What began as headline-grabbing incidents in 2021 has evolved into recurring exploitation chains and novel persistence techniques in hybrid and cloud-connected environments. At wizlynx group, our recent infrastructure tests show spooler-related attack paths remain an active risk — especially where legacy drivers, misconfigured Active Directory, or limited monitoring intersect.
We believe it’s essential to reexamine these quieter threats. In this blog, we’ll explain why print services still matter, outline realistic attack scenarios, and share practical mitigations you can apply today.
What is spooling — and why does it still matter?
Spooling stands for Simultaneous Peripheral Operations On-Line. It refers to queuing data—most often print jobs—for delayed processing. When a document is printed, it is temporarily stored in a spool file until the printer is ready to process it. That queueing process is operationally useful, but in many environments, the temporary storage lacks robust security controls.
At first glance, this process may seem harmless. However, in many environments, the temporary storage space lacks proper security controls. The Windows Print Spooler often runs with SYSTEM privileges. That privileged context makes print spooler vulnerabilities a practical path for privilege escalation, lateral movement, and persistence when attackers find misconfigurations or unpatched code.
From PrintNightmare to Now: A Quick Recap
The PrintNightmare incidents (CVE-2021-34527 and related flaws) put spooler security on the map. It allowed remote attackers to execute code with elevated privileges through the Print Spooler service. But those CVEs were not a permanent fix — they were a reminder. Although Microsoft released emergency patches, the incident exposed a broader problem: many organizations still run environments that are vulnerable by default or misconfiguration.
Even today, many organizations still:
- Leave Print Spooler active on domain controllers or sensitive assets
- Apply patches inconsistently or without verification
- Maintain poorly enforced Group Policy Object (GPO) controls
- Depend on legacy applications that require spooler functionality
- Overlook spooler activity in SIEM dashboards and endpoint logs
These conditions illustrate why spooler risks persist and why they deserve more attention in modern infrastructure security.
- For specific defensive topics that intersect with spooler risks, see our related WLX posts on lateral movement in hybrid environments and Active Directory testing: Lateral Movement Simulation in Hybrid Environments and Active Directory Red Team Testing.
Why Print Spooler vulnerabilities remain relevant in 2025
Although spooler issues may seem outdated, they remain relevant for several key reasons:
1. Operational dependencies (legacy + cloud hybrid)
Many organizations still depend on legacy print drivers or business applications that require spooler functionality. In cloud-first migrations, teams sometimes keep on-prem services active to preserve compatibility — and those services become weak links.
2. Privilege escalation and lateral movement
Because the print spooler can run with SYSTEM privileges, a vulnerable spooler frequently enables privilege escalation. When combined with Active Directory weaknesses — see our deep dives on Kerberoasting and password cracking techniques — attackers can escalate and move laterally quickly. (See: Kerberoasting — Active Directory attack and Password cracking techniques — Red Team.)
3. Poor visibility and monitoring
Spooler activity commonly flies under the radar in SIEM and EDR rules. Unusual DLL loads, failed print-job attempts, or changes in driver installation logs frequently fail to trigger alerts, letting attackers persist undetected.
4. IoT and embedded spooling
Spooling behaviours exist beyond Windows desktops. Network printers, multifunction devices (MFDs), and some industrial or medical devices implement queueing mechanisms that can be abused. These endpoints often sit outside centralised patching and may use insecure protocols (IPP, LPD, or even FTP), creating cross-domain pivot points.
Beyond Printers: Spooling Risks in IoT and Embedded Systems
While print spooler vulnerabilities are most commonly associated with Windows desktops or network printers, the risk extends beyond traditional IT infrastructure. Today, many IoT and embedded systems include spooling functionality as well.
For instance, network-connected printers, multifunction devices (MFDs), and some industrial or medical equipment queue tasks using spooling mechanisms. These devices often run lightweight operating systems and:
- Skip standard authentication requirements
- Communicate using insecure or outdated protocols (e.g., IPP, LPD, FTP)
- Operate outside centralized monitoring and patching frameworks
Because of these limitations, attackers have used compromised IoT print devices as pivot points to gain access to internal networks. In other cases, they have exfiltrated sensitive documents from memory or spool caches.
As smart devices become more widespread, spooling vulnerabilities evolve into a broader, cross-domain attack surface—not just a printer problem.
Realistic Threat Scenarios Involving Print Spooler Exploits
Although PrintNightmare no longer dominates news cycles, attackers still employ similar techniques. The following scenarios, inspired by real-world threat behaviors and testing simulations, demonstrate how overlooked vulnerabilities in spooler services can lead to serious compromises—particularly when combined with weaknesses in Active Directory, legacy software, or inconsistent patching.
Scenario 1: SYSTEM Privilege Escalation via Print Spooler
Consider a mid-sized enterprise where an employee clicks a phishing link. The attacker gains access to a Windows 10 endpoint with outdated security patches. By exploiting CVE-2021-1675, the attacker escalates privileges to SYSTEM, harvests cached credentials, and pivots laterally toward internal file servers. Without raising alarms, the attacker retrieves sensitive HR documents and internal data templates.
Scenario 2: Relay and Impersonation via RODC Spooler Access
In another example, based on tactics seen in Mimikatz abuse and Kerberos relay attacks, a hybrid AD environment includes a read-only domain controller (RODC) with the Print Spooler service unintentionally active.
An attacker who’s already on the network performs a printer bug relay attack, capturing privileged credentials via NTLM relay and leveraging Active Directory delegation misconfigurations to impersonate domain users. They establish persistence, access production systems, and remain undetected—taking advantage of the low logging profile of print services.
This scenario echoes patterns observed in research by security teams responding to attacks on manufacturing and critical infrastructure environments.
See: CERT Coordination Center on NTLM Relay Abuse
Scenario 3: Driver-Based Persistence on a Branch Print Server
Consider an attacker with administrative access on a branch office print server. Drawing from real-world malware such as Stuxnet and UNC2452’s driver abuse techniques, the adversary uploads a signed but vulnerable driver. Due to absent whitelisting controls and permissive update policies, the driver reloads on every reboot, creating a persistence mechanism with low detection probability.
This type of tactic has been noted in advanced persistent threat (APT) campaigns where seemingly innocuous components like printer drivers are weaponised for stealth and control.
Key Takeaway
Spooler misconfigurations may seem minor, but they often lead to major consequences. When overlooked, they give attackers the tools to escalate access, maintain persistence, and exfiltrate sensitive data. Security teams should not treat print services as low-priority systems. Instead, spooler-related risks must be included in threat modeling and internal assessments—especially within complex, hybrid, or legacy environments.
Mitigating Spooling Risks: Practical Recommendations
Our red teamers and infrastructure testers still encounter Print Spooler vulnerabilities in what’s left of 2025, during hybrid and cloud-linked network assessments, routinely uncovering spooler-based attack paths that traditional scans miss. The following actions can help reduce exposure significantly:
- Disable Print Spooler on systems where it is unnecessary, especially on domain controllers
- Apply updates promptly and verify their deployment using reporting tools
- Limit access to spool folders via proper ACLs and GPOs
- Enforce signed driver policies to block unverified or vulnerable installations
- Monitor spooler-related activity, including unusual DLL loads or failed job attempts
- Audit AD delegation and NTLM relay configurations to reduce lateral movement risk
For detailed guidance and frameworks, consider referencing the following trusted resources:
Why Print Spooler Vulnerabilities Still Matter in 2025
Print Spooler vulnerabilities may no longer dominate security news, but they continue to present silent, high-impact risks in today’s interconnected environments. Whether buried inside a forgotten print server or running on an IoT device, spooling services can expose your organization to attackers—especially if left unmonitored or unpatched.
Fortunately, offensive testing offers a proactive solution. Through red teaming and internal infrastructure assessments, wizlynx group can help your organization identify and resolve these threats early, responsibly and effectively.
Ready to discover what’s hiding in your digital blind spots?
Continuous assessments can help uncover Print Spooler vulnerabilities before they are exploited in production. Contact wizlynx group to schedule an infrastructure assessment or red team engagement tailored to your environment.