SMB Signing Disabled 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 long time but has proven either difficult to detect, difficult to resolve or prone to being overlooked entirely.
Contents: SMB Signing Disabled
Vital information on this issue
Scanning For and Finding Vulnerabilities in SMB Signing Disabled
Penetration Testing (Pentest) for this Vulnerability
Security updates on Vulnerabilities in SMB Signing Disabled
Confirming the Presence of Vulnerabilities in SMB Signing Disabled
False positive/negatives
Patching/Repairing this vulnerability
What is SMB Signing Disabled?
Vulnerability Name:
SMB Signing Disabled
Test ID:
14300
Risk:
Medium
Category:
SMB/NetBIOS
Type:
Attack
Summary:
Signing is disabled on the remote SMB server. This can allow man-in-the-middle attacks against the SMB server. SMB servers should both require signatures as well as support them.
Value Name: EnableSecuritySignature Data Type: REG_DWORD Data: 1 (enable) Value Name: RequireSecuritySignature Data Type: REG_DWORD Data: 1 (enable) On Windows Desktops: * HKEY_LOCAL_MACHINESystemCurrentControlSetServicesLanManWorkstationParameters Value Name: EnableSecuritySignature Data Type: REG_DWORD Data: 1 (enable) Value Name: RequireSecuritySignature Data Type: REG_DWORD Data: 1 (enable)
Impact:
Successful exploitation could allow remote attackers to gain sensitive information.
How do I Fix SMB Signing Disabled?
Enforce message signing in the host’s configuration. On Samba, the setting is called ‘server signing’. On Windows Servers: * HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesLanManServerParameters
Scanning For and Finding Vulnerabilities in SMB Signing Disabled
Use of Vulnerability Management tools, like Beyond Security’sbeSECURE(Automated Vulnerability Detection Software), 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 scanning solution or set of test tools should make this not just possible, but easy and affordable. If that is not the case, please consider beSECURE.
Penetration Testing (pentest) for this Vulnerability
The SMB Signing Disabled vulnerability is prone to false positive reports by most vulnerability assessment solutions. beSECURE 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 Signing Disabled 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 bybeSECURE.
Security Updates on Vulnerabilities in SMB Signing Disabled
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 Signing Disabled
beSECURE 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, pleaserequest a demonstration of beSECURE.
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 Signing Disabled ,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.
Patching/Repairing this Vulnerability
Run Windows Update and update the listed hotfixes or download and update mentioned hotfixes in the advisory
Vulnerabilities in SMB Signing Disabled 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.
beSECURE can scan tens of thousands of IPs in large environments with segmented or distributed networks, and generate remediation tickets when vulnerabilities are found — and then track them within the system.
SMB Signing Disabled 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 long time but has proven either difficult to detect, difficult to resolve or prone to being overlooked entirely.
In combination with systems where SMB signing is disabled, an attacker or malicious person can, by performing an NTLM relay attack, increase the privileges within the network. Depending on the network environment an attacker may be able to increase privileges to the highest level.
There are several direct mitigations for securing SMB, many of which are low or no cost to an organization: Update and Patch Against SMB Vulnerabilities. Block SMB at the Network Level. Restrict and Protect SMB at the Host Level.
Within the policy navigate to Computer Configuration > Policies > Windows Settings > Security Settings > Local Policies > Security Options. There are 4 policy items that can be modified depending on your needs. All of these policy items can either be enabled or disabled.
The remote SMB server is configured without the requirement for message signing. This absence of a signing mandate creates a vulnerability that can be exploited by an unauthenticated, remote attacker.
By implementing SMB signing, organizations can ensure the integrity of their data and detect potential attacks. Key benefits of enabling this measure include: Increased security: SMB signing helps detect unauthorized access to data and protect against potential attacks.
In the Local Group Policy Editor, navigate to Computer Configuration\Windows Settings\Security Settings\Local Policies\Security Options. Open Microsoft network client: Digitally sign communications (always), select Enabled, then select OK.
Solution. Enforce message signing in the host's configuration. On Windows, this is found in the policy setting 'Microsoft network server: Digitally sign communications (always)'. On Samba, the setting is called 'server signing'.
Small and medium-sized businesses (SMBs) are often targeted by cyberattacks due to misconfigured security systems, weak credentials, and insecure mobile devices. Attackers exploit misconfigured security systems to gain access to sensitive data.
EternalBlue. The EternalBlue vulnerability was discovered by the US National Security Agency (NSA) and published in 2017 by The Shadow Brokers (TSB) hacker group. ...
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.
SMB signing helps secure communications and data across the networks, there is a feature available which digitally signs SMB communications between devices at the packet layer. When you enable this feature the recipient of the SMB communication to authenticate who they are and confirm that the data is genuine.
All Windows and Windows Server versions support SMB signing, and the feature is now enabled by default for all connections, starting with Windows 11 insider preview build 25381 Enterprise editions, released in the Canary channel.
Under the More Windows features panel, scroll to the SMB Direct selection and ensure it is checked. You may need to restart your Windows system after performing this change for it to take effect.
SMB is a fundamental protocol for resource sharing, offering immense benefits for collaborative work and data access. However, its historical vulnerabilities, including the potential for relay attacks, make it a prime target for malicious actors.
SMBv1 should be disabled on all systems that do not have a business justification to warrant continued use. For instructions, see: How to detect, enable and disable SMBv1, SMBv2, and SMBv3 in Windows.
Vulnerability. The SMBGhost affects the latest version of the Server Message Block (SMB) protocol. SMB is a Windows service which is used for remote file and printer sharing. This vulnerability is caused by incorrectly handling the data compression in the protocol.
Introduction: My name is Gregorio Kreiger, I am a tender, brainy, enthusiastic, combative, agreeable, gentle, gentle person who loves writing and wants to share my knowledge and understanding with you.
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