SMB Port 139 and 445 Vulnerability Exploitation Fix | Beyond Security (2024)

Contents

  • Vital information on this issue
  • Scanning For and Finding Vulnerabilities in SMB Listens on Port
  • Penetration Testing (Pentest) for this Vulnerability
  • Security updates on Vulnerabilities in SMB Listens on Port
  • Disclosures related to Vulnerabilities in SMB Listens on Port
  • Confirming the Presence of Vulnerabilities in SMB Listens on Port
  • False positive/negatives
  • Patching/Repairing this vulnerability
  • Exploits related to Vulnerabilities in SMB Listens on Port

What is SMB Listens on Port?

Vulnerabilities in SMB Listens on Port is a Medium risk vulnerability that is one of the most frequently found on networks around the world. This issue has been around since at least 1990 but has proven either difficult to detect, difficult to resolve or prone to being overlooked entirely.

Vulnerability Name:SMB Listens on Port
Test ID:1782
Risk:Medium
Category:SMB/NetBIOS
Type:Attack
Summary:Ports 139 and 445 are used for ‘NetBIOS’ communication between two Windows 2000 hosts. In the case of port 445 an attacker may use this to perform NetBIOS attacks as it would on port 139.
Impact:All NetBIOS attacks are possible on this host.
Solution:Filter incoming traffic to this port.
CVE:
More information:
Nist NVD (CVSS):
CVSS Score:

Scanning For and Finding Vulnerabilities in SMB Listens on Port

Use ofvulnerability scanner tools, like AVDS, are standard practice for the discovery of this vulnerability. The primary failure of VA in finding this vulnerability is related to setting the proper scope and frequency of network scans. It is vital that the broadest range of hosts (active IPs) possible are scanned and that scanning is done frequently. We recommend weekly. Your existing port scanner solution or set of test tools should make this not just possible, but easy and affordable. If that is not the case, please consider AVDS.

Penetration Testing (pentest) for SMB Listens on Port

The Vulnerabilities in SMB Listens on Port is prone to false positive reports by most vulnerability assessment solutions. AVDS is alone in using behavior based testing that eliminates this issue. For all other VA tools security consultants will recommend confirmation by direct observation. In any case Penetration testing procedures for discovery of Vulnerabilities in SMB Listens on Port produces the highest discovery accuracy rate, but the infrequency of this expensive form of testing degrades its value. The ideal would be to have pentesting accuracy and the frequency and scope possibilities of VA solutions, and this is accomplished only by AVDS.

Security Updates on Vulnerabilities in SMB Listens on Port

Given that this is one of the most frequently found vulnerabilities, there is ample information regarding mitigation online and very good reason to get it fixed. Hackers are also aware that this is a frequently found vulnerability and so its discovery and repair is that much more important. It is so well known and common that any network that has it present and unmitigated indicates “low hanging fruit” to attackers.

Contents

  • Vital information on this issue
  • Scanning For and Finding Vulnerabilities in SMB Listens on Port
  • Penetration Testing (Pentest) for this Vulnerability
  • Security updates on Vulnerabilities in SMB Listens on Port
  • Disclosures related to Vulnerabilities in SMB Listens on Port
  • Confirming the Presence of Vulnerabilities in SMB Listens on Port
  • False positive/negatives
  • Patching/Repairing this vulnerability
  • Exploits related to Vulnerabilities in SMB Listens on Port

What is SMB Listens on Port?

Vulnerabilities in SMB Listens on Port is a Medium risk vulnerability that is one of the most frequently found on networks around the world. This issue has been around since at least 1990 but has proven either difficult to detect, difficult to resolve or prone to being overlooked entirely.

Vulnerability Name:SMB Listens on Port
Test ID:1782
Risk:Medium
Category:SMB/NetBIOS
Type:Attack
Summary:Ports 139 and 445 are used for ‘NetBIOS’ communication between two Windows 2000 hosts. In the case of port 445 an attacker may use this to perform NetBIOS attacks as it would on port 139.
Impact:All NetBIOS attacks are possible on this host.
Solution:Filter incoming traffic to this port.
CVE:
More Information:
Nist NVD (CVSS):
CVSS Score:

Scanning For and Finding Vulnerabilities in SMB Listens on Port

Use ofvulnerability scanner tools, like AVDS, are standard practice for the discovery of this vulnerability. The primary failure of VA in finding this vulnerability is related to setting the proper scope and frequency of network scans. It is vital that the broadest range of hosts (active IPs) possible are scanned and that scanning is done frequently. We recommend weekly. Your existing port scanner solution or set of test tools should make this not just possible, but easy and affordable. If that is not the case, please consider AVDS.

Penetration Testing (pentest) for SMB Listens on Port

The Vulnerabilities in SMB Listens on Port is prone to false positive reports by most vulnerability assessment solutions. AVDS is alone in using behavior based testing that eliminates this issue. For all other VA tools security consultants will recommend confirmation by direct observation. In any case Penetration testing procedures for discovery of Vulnerabilities in SMB Listens on Port produces the highest discovery accuracy rate, but the infrequency of this expensive form of testing degrades its value. The ideal would be to have pentesting accuracy and the frequency and scope possibilities of VA solutions, and this is accomplished only by AVDS.

Security Updates on Vulnerabilities in SMB Listens on Port

Given that this is one of the most frequently found vulnerabilities, there is ample information regarding mitigation online and very good reason to get it fixed. Hackers are also aware that this is a frequently found vulnerability and so its discovery and repair is that much more important. It is so well known and common that any network that has it present and unmitigated indicates “low hanging fruit” to attackers.

Confirming the Presence of Vulnerabilities in SMB Listens on Port

AVDS is currently testing for and finding this vulnerability with zero false positives. If your current set of tools is indicating that it is present but you think it is probably a false positive, please contact us for a demonstration of AVDS.

False positive/negatives

The secret killer of VA solution value is the false positive. There was an industry wide race to find the most vulnerabilities, including Vulnerabilities in SMB Listens on Port ,and this resulted in benefit to poorly written tests that beef up scan reports by adding a high percentage of uncertainty. This may have sold a lot of systems some years ago, but it also stuck almost all VA solutions with deliberately inaccurate reporting that adds time to repairs that no administrator can afford. Beyond Security did not participate in this race to mutually assured destruction of the industry and to this day produces the most accurate and actionable reports available.

SMB Port Exploitation

Vulnerabilities in SMB Listens on Port is a Medium risk vulnerability that is also high frequency and high visibility. This is the most severe combination of security factors that exists and it is extremely important to find it on your network and fix it as soon as possible.

Get a demo and see how vulnerability scanning can help your online security.

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SMB Port 139 and 445 Vulnerability Exploitation Fix | Beyond Security (2024)

FAQs

Why is port 445 and 139 vulnerable? ›

Ports 139 and 445 are used for 'NetBIOS' communication between two Windows 2000 hosts. In the case of port 445 an attacker may use this to perform NetBIOS attacks as it would on port 139. Impact: All NetBIOS attacks are possible on this host.

What are SMB ports 445 and 139? ›

SMB uses either IP port 139 or 445.
  • Port 139: SMB originally ran on top of NetBIOS using port 139. NetBIOS is an older transport layer that allows Windows computers to talk to each other on the same network.
  • Port 445: Later versions of SMB (after Windows 2000) began to use port 445 on top of a TCP stack.

Is SMB port 445 secure? ›

Security implications of SMB ports

Ports 139 and 445 have been targets for various cyberattacks, including the notorious WannaCry ransomware. These attacks exploit vulnerabilities in the SMB protocol to execute malicious code and spread across networks.

Why is SMB port vulnerable? ›

Why is it a risk? Version 1.0 of SMB contains a bug that can be used to take over control of a remote computer. The US National Security Agency (NSA) developed an exploit (called “EternalBlue”) for this vulnerability which was subsequently leaked.

What is SMB port 445 used for? ›

Port 445 is a Microsoft networking port which is also linked to the NetBIOS service present in earlier versions of Microsoft Operating Systems. It runs Server Message Block (SMB), which allows systems of the same network to share files and printers over TCP/IP. This port shouldn't be opened for external network.

Is port 139 vulnerable? ›

Port 139, primarily used by the Server Message Block (SMB) protocol for file sharing in Windows networks, stands out as a critical point of vulnerability when not properly secured. This port facilitates network communications, allowing computers to share files, printers, and serial ports over a network.

Why port 445 should be closed? ›

Attacks Against Port 445 In the Past

Hackers have used port 445 to infiltrate devices on a network, most famously by the WannaCry ransomware attack. They do this by scanning services that use the port, which allows them to gather sensitive information about devices on the network.

What are some potential vulnerabilities with having port 445 open? ›

SMB 445/TCP is a Microsoft Windows file sharing protocol that can be exploited to spread malware like "Wannacry" ransomware, "SambaCry" ransomware on IoT devices, Cryptocurrency-Mining, and similar threats.

How do I block SMB 445 port? ›

Step 1: Open the Control Panel Step 2: Click on Windows Firewall/ Windows Defender firewall Step 3: Navigate to advanced settings. Step 4:Right click on inbound rules and click on new rule. Step 6:Select port and press next Step 7:Specify the port 445 under specific local ports, select TCP and press next.

Is SMB a security risk? ›

SMB relay attacks exploit SMB's NTLM authentication, potentially allowing attackers to impersonate users and gain unauthorized access.

Is SMB still vulnerable? ›

The first version of the protocol – SMB v1 – was full of vulnerabilities that could be easily exploited. Today, the updated protocol is more secure, but SMB v1 exploits continue to happen because many machines still use the old and much more insecure protocol.

Is SMB protocol obsolete? ›

Microsoft has marked SMB1 as deprecated in June 2013. Windows Server 2016 and Windows 10 version 1709 do not have SMB1 installed by default.

What ports do hackers use? ›

These are the ports most targeted by attackers:
  • Ports 137 and 139 (NetBIOS over TCP) and 445 (SMB)
  • Port 22 (SSH)
  • Port 53 (DNS)
  • Port 25 (SMTP)
  • Port 3389 (remote desktop)
  • Ports 80, 443, 8080 and 8443 (HTTP and HTTPS)
  • Ports 20 and 21 (FTP)
  • Port 23 (Telnet)

What ports are most often scanned by hackers? ›

Commonly hacked TCP port numbers include port 21 (FTP), port 22 (SSH), port 23 (Telnet), port 25 (Simple Mail Transfer Protocol or SMTP), port 110 (POP3), and port 443 (HTTP and Hypertext Transfer Protocol Secure or HTTPS).

What is the most vulnerable port? ›

The greatest number of attacks occur on ports 22, 80, and 443, which are typically open for secured and plain text communication. Windows Remote Desktop Protocol (RDP) is widely used for remote communication and has a large number of CVEs and patches for remote code execution vulnerabilities.

What port is the most vulnerable? ›

What are risky network ports? These are the ports most targeted by attackers: Ports 137 and 139 (NetBIOS over TCP) and 445 (SMB) Port 22 (SSH)

What is port 139 commonly used for? ›

Port 139 is utilized by NetBIOS Session service. Enabling NetBIOS services provide access to shared resources like files and printers not only to your network computers but also to anyone across the internet. Therefore it is advisable to block port 139 in the Firewall.

Why block port 445? ›

We also recommend blocking port 445 on internal firewalls to segment your network and prevent lateral movement – this will prevent internal spreading of the ransomware.

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