CVE-2024-21406: Windows 10 1607 Spoofing Vulnerability

CVE-2024-21406 Overview

CVE-2024-21406 is a spoofing vulnerability in the Windows Printing Service that allows a remote, unauthenticated attacker to compromise the integrity of print-related communications. The flaw is associated with [CWE-319: Cleartext Transmission of Sensitive Information], indicating that sensitive print service data traverses the network without sufficient protection. Microsoft addressed the issue in the February 2024 Patch Tuesday cycle. The vulnerability affects a broad set of Windows client and server releases, including Windows 10, Windows 11, and Windows Server editions from 2008 through 2022 23H2.

Critical Impact
A network attacker can spoof Windows Printing Service traffic to tamper with print operations or impersonate trusted components without requiring authentication or user interaction.

Affected Products

Microsoft Windows 10 (versions 1607, 1809, 21H2, 22H2)
Microsoft Windows 11 (versions 21H2, 22H2, 23H2)
Microsoft Windows Server 2008, 2012, 2016, 2019, 2022, and 2022 23H2

Discovery Timeline

2024-02-13 - CVE-2024-21406 published to the National Vulnerability Database (NVD)
2024-02-13 - Microsoft releases security update via the Microsoft Security Update Guide
2024-11-21 - Last updated in NVD database

Technical Details for CVE-2024-21406

Vulnerability Analysis

The vulnerability resides in the Windows Printing Service, the component responsible for handling print job submission, spooling, and inter-process communication between print clients and servers. The flaw allows an attacker on an adjacent network path to spoof responses or identities within the print service exchange. Because the attack vector is network-based and requires neither privileges nor user interaction, exploitation can be launched from any host that can reach a vulnerable print service endpoint.

Successful exploitation primarily impacts integrity. An attacker can manipulate print-related data flows, inject crafted responses, or impersonate legitimate print service participants. Confidentiality and availability are not directly affected by this specific vulnerability.

Root Cause

The root cause is mapped to [CWE-319: Cleartext Transmission of Sensitive Information]. The Windows Printing Service transmits or accepts data over channels lacking adequate authentication or integrity verification. This permits a network-positioned adversary to forge messages that the service treats as trustworthy.

Attack Vector

Exploitation occurs over the network. An attacker who can observe or intercept Windows Printing Service traffic, or who can reach the print service directly, can craft spoofed messages to influence print operations. Typical attack scenarios include man-in-the-middle positioning on internal network segments or rogue hosts on the same broadcast domain as the target. No verified public proof-of-concept is currently available, and the vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog.

For technical specifics, refer to the Microsoft Security Update Guide entry for CVE-2024-21406.

Detection Methods for CVE-2024-21406

Indicators of Compromise

Unexpected print jobs originating from unrecognized hosts or service accounts on the print server
Anomalous SMB or RPC traffic patterns to the spooler service (spoolsv.exe) from non-print clients
Print spooler log entries showing failed or malformed authentication exchanges between clients and the print service

Detection Strategies

Monitor Windows Event Logs under Microsoft-Windows-PrintService/Operational and Microsoft-Windows-PrintService/Admin for unusual job submission or driver-related events
Inspect network traffic to TCP ports 445 and 135, and RPC dynamic ports, for unexpected sources interacting with print services
Correlate spoolsv.exe child process activity with parent-child relationships that deviate from baseline behavior

Monitoring Recommendations

Baseline normal print server clients and alert on new or unauthorized hosts initiating print sessions
Forward print service and security event logs to a centralized SIEM for cross-host correlation
Track patch compliance for KB updates referenced in the February 2024 Microsoft security release across all Windows endpoints and servers

How to Mitigate CVE-2024-21406

Immediate Actions Required

Apply the February 2024 Microsoft security updates referenced in the MSRC advisory to all affected Windows client and server systems
Inventory hosts running the Print Spooler service and prioritize patching of internet-exposed or domain-joined print servers
Restrict network access to print services using host-based firewalls and network segmentation

Patch Information

Microsoft published fixes through the standard Windows Update channel. Administrators should consult the Microsoft Security Update Guide for CVE-2024-21406 for the specific KB article applicable to each Windows version and install the corresponding cumulative update.

Workarounds

Disable the Print Spooler service (Spooler) on servers and workstations that do not require printing functionality
Limit inbound RPC and SMB traffic to print servers from authorized client subnets only
Enforce SMB signing and require authentication on print server endpoints to reduce exposure to spoofing on the network path

bash

# Disable the Print Spooler service on systems that do not need it
Stop-Service -Name Spooler -Force
Set-Service -Name Spooler -StartupType Disabled