HACKERS’ DREAM: Watchdoc Print Server Flaw (CVE-2025-88990) is a CVSS 10.0 RCE

By CyberDudeBivash • October 01, 2025, 07:58 PM IST • Critical Vulnerability Alert

A critical vulnerability has been discovered in the Watchdoc print management solution that can only be described as a hacker’s dream. The flaw, designated **CVE-2025-88990**, is an unauthenticated Remote Code Execution (RCE) vulnerability that has been assigned the maximum possible severity score: **CVSS 10.0**. This is not a drill. An unauthenticated attacker can exploit this flaw to gain complete, SYSTEM-level control of your print server. While often overlooked, a print server is a perfect staging ground for a full-scale enterprise compromise. It’s highly connected, highly privileged, and often poorly monitored. This is the ideal pivot point for ransomware gangs. An emergency patch is available from the vendor, Doxense, and it must be applied with the highest possible urgency.

Disclosure: This is an urgent security advisory for system administrators, security engineers, and IT leaders. It contains our full suite of affiliate links to best-in-class security solutions. Your support helps fund our independent research.

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• YubiKey for Domain Admin Accounts — Protect the high-value accounts attackers will try to steal from the compromised server.

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 Threat Report: Table of Contents 

1. Chapter 1: The Forgotten Gateway — Why Print Servers Are a Prime Target
2. Chapter 2: Threat Analysis — The CVSS 10.0 Arbitrary File Upload
3. Chapter 3: The Kill Chain — From Printer to Domain Controller
4. Chapter 4: The Defender’s Playbook — Emergency Patching and Hardening
5. Chapter 5: FAQ — Answering Your Print Security Questions

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Chapter 1: The Forgotten Gateway — Why Print Servers Are a Prime Target

In the hierarchy of an enterprise network, the print server is often a forgotten soldier. It’s a piece of critical infrastructure that just works… until it doesn’t. But from an attacker’s perspective, it’s a gold mine:

• Highly Connected:** It communicates with nearly every workstation and user on the network.
• Highly Privileged:** It often runs with high-level service accounts and may even cache the credentials of domain administrators who have logged in to manage it.
• Poorly Monitored:** Unlike web servers or domain controllers, print servers are frequently overlooked by security monitoring tools, making them a perfect place for an attacker to hide.

This combination makes a print server the ideal pivot point for an attacker to turn a single server compromise into a full-domain takeover.

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Chapter 2: Threat Analysis — The CVSS 10.0 Arbitrary File Upload

The core of CVE-2025-88990 is a **pre-authentication arbitrary file upload** vulnerability in the Watchdoc’s embedded web server.

The Exploit Mechanism

1. The Vulnerable Endpoint:** The web interface has a file upload component that is accessible without a valid session cookie or authentication.
2. The Flaw:** This component lacks two critical checks. First, it doesn’t verify authentication. Second, it doesn’t properly sanitize the filename or path. An attacker can use path traversal sequences (`../`) to control the destination directory of the uploaded file.
3. **The Exploit:** An attacker crafts a simple HTTP POST request. They specify the file to upload (a malicious webshell, e.g., `cmd.aspx`) and craft the destination path to place it in a web-accessible directory, such as `C:\inetpub\wwwroot\Watchdoc\`.
4. **Remote Code Execution:** The attacker then simply navigates to the URL of their uploaded webshell (e.g., `http://[printserver-ip]/cmd.aspx`). Because the application pool runs as `NT AUTHORITY\SYSTEM`, the webshell executes with the highest possible privileges on the server.

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Chapter 3: The Kill Chain — From Printer to Domain Controller

This vulnerability is a direct on-ramp for a full-scale ransomware attack.

1. **Scanning & Initial Access:** Attackers use mass scanners to find exposed Watchdoc web interfaces and exploit CVE-2025-88990 to upload a webshell, gaining a SYSTEM-level foothold.
2. **Credential Dumping:** This is the attacker’s first priority. They use their webshell to execute a tool like Mimikatz directly in the server’s memory. The print server, having authenticated many users, is likely to have valuable credentials cached in the LSASS process memory, including those of Domain Administrators.
3. **Lateral Movement:** Armed with stolen Domain Admin credentials, the attacker uses standard Windows tools (like PsExec or WMI) to move laterally from the print server to a Domain Controller.
4. **Full Domain Compromise:** Once on the Domain Controller, the attacker has complete control of the Active Directory. They can create new accounts, escalate privileges, and disable security controls.
5. **Ransomware Deployment:** From the Domain Controller, the attacker uses Group Policy or other deployment scripts to push ransomware to every single computer on the network, causing a catastrophic, enterprise-wide incident.

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Chapter 4: The Defender’s Playbook — Emergency Patching and Hardening

Your response must be immediate and decisive.

Step 1: Apply the Emergency Patch

This is the highest priority. Doxense has released a security update for Watchdoc. You must apply this patch immediately. This is the only way to fix the vulnerability.

Step 2: Isolate the Server (If You Cannot Patch)

If you have a complex environment and cannot patch immediately, the only safe alternative is to take the server offline by shutting it down or disconnecting it from the network. If that’s not possible, use a network firewall to strictly limit access to the server’s web interface to only dedicated administrator workstations.

Step 3: Hunt for Indicators of Compromise (IOCs)

Assume you have been breached and hunt for signs of compromise.

• **Scan Web Directories:** Search all web-accessible directories on the print server (e.g., `C:\inetpub\wwwroot\`) for any unexpected or recently created `.aspx`, `.php`, or `.jsp` files.
• **Analyze IIS Logs:** Review the web server logs for any POST requests to file upload endpoints, especially any from unknown IP addresses.
• **Use an EDR:** The most effective way to hunt is with an **EDR solution**. Hunt for suspicious processes being spawned by the IIS worker process (`w3wp.exe`), such as `cmd.exe`, `powershell.exe`, or any signs of credential dumping tools running in memory.

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Chapter 5: FAQ — Answering Your Print Security Questions

Q: Our print server is on an internal network, not exposed to the internet. Are we safe?
A: You are protected from a direct, unauthenticated attack from the public internet. However, you are **not** safe from an attacker who has already gained an initial foothold on your internal network (e.g., via a phishing email that compromised a user’s workstation). That attacker will scan your internal network, find the vulnerable print server, and use this CVSS 10.0 exploit to immediately escalate their privileges to SYSTEM and begin their attack on your Domain Controllers. The patch is mandatory for all instances, both internal and external.

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About the Author

CyberDudeBivash is a cybersecurity strategist and researcher with over 15 years of experience in Windows security, incident response, and defending against advanced ransomware attacks. He provides strategic advisory services to CISOs and boards across the APAC region. [Last Updated: October 01, 2025]

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