Listen to this Post
How the Mentioned CVE Works
The vulnerability, CVE-2025-62221, is a Use-After-Free (UAF) flaw within the Windows Cloud Files Mini Filter Driver (cldflt.sys). This driver manages the synchronization and offline states of files for cloud storage services like OneDrive. The UAF condition occurs when the driver fails to properly manage system memory objects during specific file operation sequences.
When a user or process initiates a file operation that interacts with a cloud-synced file, the mini-filter driver allocates a memory object to track this operation. If the operation is canceled or encounters a specific error state, the driver may incorrectly release (free) the associated memory object while a pointer to it remains active elsewhere in the system. This results in a “dangling pointer.”
A local, authenticated attacker can exploit this by crafting a sequence of file operations to trigger the flawed cancellation path, deliberately creating the UAF condition. Following this, the attacker can manipulate the system to reallocate the freed memory region with attacker-controlled data. When the driver subsequently attempts to use the original, now-dangling pointer, it inadvertently executes or interacts with the attacker’s data.
This corrupts the driver’s execution flow in kernel memory, allowing the attacker to execute arbitrary code with elevated SYSTEM privileges. Successful exploitation bypasses user-mode access controls, enabling full compromise of the affected system. The attack is reliable due to the predictable nature of kernel memory management and the driver’s failure to validate object lifetimes.
DailyCVE Form
Platform: Windows
Version: Multiple Versions
Vulnerability: Use After Free
Severity: High
Date: 2025-12-09
Prediction: Expected January 2026
What Undercode Say
Analytics
Check for the vulnerable driver file version
Get-Command powershell
Get-WmiObject Win32_PnPSignedDriver | Where-Object {$_.DeviceName -like "cldflt"} | Select-Object DeviceName, DriverVersion, DriverDate
General command to list loaded kernel modules (admin required)
sc query type= driver
Note: The provided URL content from NIST does not contain specific bash commands, exploit codes, or analytical data related to CVE-2025-62221. The commands above are generic examples for driver investigation.
How Exploit
- An attacker gains initial execution as a low-privileged user on the target system.
- A malicious program is run to perform repeated, specially crafted file operations on cloud-synced directories.
- The operations are designed to trigger the cancellation error path in the `cldflt.sys` driver.
- This forces the driver to free a memory object while keeping a reference.
- The program quickly reallocates that memory with payload data.
- When the driver uses the dangling reference, it executes the attacker’s payload.
- The payload runs in kernel context, granting the attacker SYSTEM privileges.
Protection from this CVE
- Apply the official security patch from Microsoft immediately upon release.
- Restrict local user permissions and employ the principle of least privilege.
- Use Windows Defender Application Control or similar to block untrusted kernel drivers.
- Monitor for and investigate unexpected process creations with SYSTEM-level integrity.
Impact
Local Privilege Escalation leading to complete system compromise, data theft, and persistent access.
🎯Let’s Practice Exploiting & Learn Patching For Free:
Sources:
Reported By: nvd.nist.gov
Extra Source Hub:
Undercode
