CIFS vs. SMB: What’s the Difference and Which Is More Secure?

CIFS vs. SMB: Understanding File Sharing Protocol Risks in 2025

Modernizing network protocols to eliminate legacy security gaps

In 2025, organizations still face cyber risks tied to outdated file-sharing protocols. The Common Internet File System (CIFS) remains active in some enterprise environments—despite being deprecated due to critical vulnerabilities. Understanding the difference between CIFS and newer Server Message Block (SMB) protocol versions is essential for IT teams managing hybrid environments and legacy infrastructure.

What Is CIFS?

CIFS is a Microsoft implementation of SMB, originally intended to support file and printer sharing across Windows systems. At the time, it addressed interoperability needs, but it lacked the encryption, authentication integrity, and efficiency required for modern use.

Today, CIFS is obsolete and considered out-of-date and risky. Microsoft formally deprecated SMBv1, and continuing to use it could expose organizations to preventable risks. Especially as threat actors increasingly probe for legacy services in hybrid and internet-facing systems, organizations can’t afford to ignore CIFS issues.

Key limitations of CIFS include:

• No default encryption or message signing

• Vulnerability to man-in-the-middle attacks
• Bad protection against downgrade attacks

SMB: A Modernized Protocol Stack

SMB has undergone several major upgrades since its initial release. Each new version introduces stronger security controls and better performance.

SMB 2.0:

• Reduced protocol “chattiness”
• Support for larger reads/writes

SMB 3.0:

• Added support for encryption of data in transit
• End-to-end encryption to protect against eavesdropping
• Enhanced support for high performance and low latency with remote direct memory access (RDMA)

SMB 3.1.1:

• Uses AES-128-GCM encryption
• Enabled pre-authentication integrity checks, preventing interception attacks

The Security Risk of Using CIFS or SMBv1

Hackers exploit legacy file-sharing protocols like CIFS and SMBv1 for ransomware and lateral movement attacks. High-profile campaigns such as WannaCry and NotPetya leveraged SMBv1 vulnerabilities to rapidly spread malware across networks.

How to Migrate Off CIFS and SMBv1

Eliminating legacy protocols requires both planning and automation, especially in large or complex infrastructures. Here’s how to approach the transition:

Inventory Protocol Usage
Identify all systems, applications, and devices that rely on SMB protocols.

Disable SMBv1
Deactivate it across all Windows systems using Group Policy or PowerShell. On Windows Server 2016 and newer, SMBv1 is disabled by default.

Enforce Encryption and Signing
Configure SMB 3.x to require encryption and more.

Restrict Network Access
Use firewalls and access control lists (ACLs) to isolate file-sharing services. Block inbound SMB traffic from untrusted sources.

Monitor for Legacy Usage
Use security information and event management (SIEM) tools to log protocol usage. Flag any attempts to use deprecated versions.

These steps are critical not only for internal risk reduction, but also for ensuring that exposed SMB services aren’t inadvertently offering attackers an easy way in.

Third-Party Risk: Insecure SMB as a Supply Chain Threat

Many ransomware actors scan for SMB exposures across the public internet. If a vendor or partner operates insecure SMB services, your network may be only one hop away from compromise.

This makes continuous third-party risk monitoring essential. 41.4% of ransomware attacks now begin with third-parties, according to SecurityScorecard data. And over 30% of data breaches in the last year stem from third-party breaches.

Regulatory Considerations

Using SMBv1 could run afoul of data protection frameworks such as:

• Health Insurance Portability and Accountability Act (HIPAA)
• National Institute of Standards and Technology (NIST) Special Publication 800-53
• International Organization for Standardization (ISO) 27001

Violations may arise when sensitive data is transmitted unencrypted or logged inadequately due to weak configurations. Ensuring secure protocol usage is a foundational compliance requirement.

Final Thoughts: Retire CIFS to Strengthen Your Enterprise

CIFS and SMBv1 served a role in the early internet—but in 2025, they present more risk than value. Organizations must proactively identify, isolate, and decommission these protocols to reduce exposure.

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