What is Windows TCP Port 135 Security Risks You Might Not Be Aware Of

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May 16, 2025

What is Windows TCP Port 135 Security Risks You Might Not Be Aware Of

TCP Port a hundred thirty five, also referred to as the Remote Procedure Call (RPC) Endpoint Mapper, is a center Windows provider used to facilitate verbal exchange among applications and community services. It allows patron packages find out the place of unique offerings on a network, playing a vital role in DCOM and other Microsoft services What is Windows TCP Port 135 Security Risks You Might Not Be.

However, Port a hundred thirty five poses severe protection dangers if left uncovered to the net. It’s a common goal for attackers aiming to exploit RPC vulnerabilities, doubtlessly permitting far flung code execution, privilege escalation, or spreading malware. Notably, some notorious worms and ransomware have used Port a hundred thirty five to propagate throughout networks.

To reduce risks, it is essential to block Port 135 at the firewall stage for outside site visitors and make certain structures are often updated. In business enterprise environments, using VPNs and network segmentation can further mitigate exposure to threats related to this port. Always audit and harden unused ports.

Introduction to Windows TCP Port 135

Windows TCP Port a hundred thirty five, additionally referred to as the RPC Endpoint Mapper, is a fundamental a part of Microsoft’s Remote Procedure Call (RPC) service. This port allows packages on extraordinary computer systems to speak with each other over a network. Specifically, it allows customer systems find the appropriate dynamic port in which a requested RPC provider is strolling. Port a hundred thirty five acts as a “traffic director,” initiating connections earlier than handing off verbal exchange to other dynamically assigned ports.

Primarily used by services like DCOM, WMI, and the Microsoft Exchange server, Port a hundred thirty five is crucial for faraway control and administrative responsibilities in business enterprise environments. However, due to its wide functionality and access degree, it’s also a commonplace attack vector if left unprotected—mainly while exposed to public networks. Understanding how Port a hundred thirty five operates and the function it plays in Windows networking is essential for IT directors seeking to keep steady and green structures.

How TCP Port a hundred thirty five Works in Windows Operating Systems

TCP Port a hundred thirty five performs a essential position in Windows running structures as part of the Remote Procedure Call (RPC) provider. It acts because the Endpoint Mapper, permitting consumer programs to locate the dynamic ports utilized by server offerings. When a client initiates a request, it connects to port one hundred thirty five, which responds with the particular port quantity in which the service is available. This method is vital for numerous Windows offerings, inclusive of DCOM and WMI.

Steps of ways it works:
1. A consumer sends a request to TCP Port a hundred thirty five.
2. The RPC Endpoint Mapper receives the request.
3. It checks the provider listing and returns the dynamic port wide variety.
4. The consumer then connects to the service on that port.

Although now not the same as an SMB port or Samba server port, port 135 is often used in similar environments and have to be secured nicely to prevent unauthorized get admission to or attacks.

The Role of Port one hundred thirty five in Remote Procedure Call (RPC)

Port one hundred thirty five, additionally called tcp port 135 TCP Port one hundred thirty five, is vital to Microsoft’s Remote Procedure Call (RPC) system. It features because the RPC Endpoint Mapper, assisting clients locate services on far off machines. When a purchaser wants to use an RPC carrier, it does not realize the exact port the carrier is running on. Instead, it connects to port a hundred thirty five, which maps the request to the appropriate dynamically assigned port.

Steps of RPC the use of Port 135:
1. The client initiates a connection to TCP Port 135.
2. The RPC Endpoint Mapper processes the request.
3. It returns the dynamic port where the provider is to be had.
4. The consumer then connects without delay to that provider port.

While port a hundred thirty five is different from an SMB port or Samba server port, it’s regularly gift inside the same network environments. Because of its network exposure, securing port one hundred thirty five is essential to prevent unauthorized get entry to and exploits.

Common Services and Applications Using Port 135

Port one hundred thirty five, additionally known as TCP Port 135, is in the main used by Microsoft’s Remote Procedure Call (RPC) service. This port is important for allowing verbal exchange between Windows-based totally packages over a network. It acts as a listing for finding dynamic ports wherein services like DCOM, WMI, and Microsoft Exchange additives are strolling.

Common services using Port a hundred thirty five:
1. DCOM (Distributed Component Object Model) – for faraway software program element interaction.
2. WMI (Windows Management Instrumentation) – for machine monitoring and remote control.
3. Microsoft Exchange Server – for electronic mail conversation and management obligations.
4. Task Scheduler and Remote Desktop Services – depend upon RPC calls initiated via port 135.

Although port a hundred thirty five isn’t like the SMB port or Samba server port, they regularly operate together in Windows file-sharing environments. For protection, it’s essential to restriction public get entry to to TCP port a hundred thirty five, mainly on net-going through systems.

Why Port a hundred thirty five Is a Security Concern

Port 135, or TCP port a hundred thirty five, is a famous access point for Remote Procedure Call (RPC) services in Windows. While critical for inner verbal exchange, it will become a serious protection issue when uncovered to the net. Attackers often test for open times of port one hundred thirty five to take advantage of RPC vulnerabilities, which could cause remote code execution, information breaches, or malware unfold.

Steps attackers may additionally use to make the most Port 135:
1. Scan networks for open TCP port 135.
2. Identify unpatched or prone services.
3. Exploit RPC-related vulnerabilities (e.G., buffer overflow).
4. Gain far off get entry to or execute malicious code.

Unlike the SMB port or Samba server port, which cope with document sharing, port 135 is focused on service discovery—but it’s similarly dangerous when uncovered. To mitigate dangers, block outside get admission to to port one hundred thirty five, follow gadget patches frequently, and use firewalls or network segmentation to guard inner structures from unauthorized access.

Port 135 has been connected to several important vulnerabilities due to its role in Microsoft’s Remote Procedure Call (RPC) device. One of the most infamous exploits became MS03-026, which focused a buffer overflow vulnerability in the RPC interface. This flaw allowed attackers to execute arbitrary code remotely, main to the fast spread of the Blaster Worm in 2003. The bug infected heaps of structures through scanning for open TCP port one hundred thirty five and exploiting the vulnerability without user interplay.

Other malware families and chance actors have additionally leveraged port 135 for reconnaissance and lateral movement in networks. Once compromised, attackers can expand privileges or install ransomware.

Because port one hundred thirty five is frequently open with the aid of default on Windows structures, it’s a frequent goal for community scans. Administrators are advised to apply all safety patches, block port a hundred thirty five on perimeter firewalls, and screen traffic for uncommon activity to prevent ability exploitation.

Real-World Cyber Attacks Involving Port a hundred thirty five

Port 135 has been a key vector in several actual-global cyber attacks because of its use in Microsoft’s RPC carrier. tcp port 135 One of the maximum infamous incidents was the Blaster Worm outbreak in 2003, which exploited a vulnerability in the RPC DCOM interface over TCP port one hundred thirty five. The trojan horse hastily inflamed systems across the globe, causing device crashes and community disruptions, and forced organizations to shut down systems to incorporate the unfold.

In extra latest years, superior persistent threats (APTs) have used port one hundred thirty five for community reconnaissance and lateral movement. By scanning for open port 135, attackers discover systems with uncovered RPC services, allowing them to map network offerings and take advantage of unpatched vulnerabilities.

How to Check If Port 135 Is Open on Your System

Checking if port a hundred thirty five (additionally referred to as TCP port one hundred thirty five) is open to your device is essential for securing your community in opposition to ability exploits. This port is utilized by Microsoft RPC offerings and should not be uncovered to the net unless without a doubt important.

Follow these steps to test if port one hundred thirty five is open:
1. Command Prompt (Windows):
  - Open Command Prompt and kind:
  - netstat -an discover “a hundred thirty five”
  - If the port is indexed as “LISTENING,” it’s open to your machine.
2. Using PowerShell:
  - Run:
  - Test-NetConnection -ComputerName localhost -Port a 135
3. Online Port Scanners:
  - Use gear like ShieldsUP! Or Nmap from some other gadget to experiment for TCP port 135.

Although port 135 isn’t the same as the SMB port or Samba server port, they often coexist in Windows environments. Always audit open ports often to lessen your device’s attack floor.

Best Practices to Secure or Disable Port 135

Securing Port one hundred thirty five (additionally called TCP port a tcp port 135 hundred thirty five) is vital, as it’s typically targeted via attackers because of its role in Windows RPC offerings. If the services the usage of this port aren’t critical, it is excellent to disable it. Otherwise, follow those nice practices to reduce risk:

Block Port one hundred thirty five on the Perimeter Firewall: Prevent outside get entry to from untrusted networks, specially the internet.
Use Host-Based Firewalls: Configure Windows Firewall to restriction incoming connections to port one hundred thirty five best from relied on IPs.
Disable Unused Services: If DCOM, WMI, or related RPC services aren’t wanted, disable them to lessen exposure.

Unlike the SMB port or Samba server port, port 135 doesn’t manage document sharing however still poses vast protection dangers.

Conclusion: Should You Close Port a hundred thirty five on Your Network?

Closing port 135 (or TCP port a hundred thirty five) is normally encouraged for most networks, especially those uncovered to the internet. While this port is important for Windows RPC services, its publicity can lead to critical safety vulnerabilities and assaults. Unlike the SMB port or Samba server port, which deal with document sharing, port 135 basically manages service discovery and far flung verbal exchange, making it a frequent target for attackers.

If your network doesn’t rely upon RPC offerings externally, it’s safer to dam or close port one hundred thirty five on the firewall to limit risks. For inner networks, limit access the usage of firewalls and ensure all systems are up to date. Overall, final or tightly controlling port 135 reduces the attack floor and strengthens your network’s security posture.