| Vulnerability Name: | NULL Session Available (SMB) |
| Test ID: | 10637 |
| Risk: | Low |
| Category: | Policy Checks |
| Type: | Attack |
| Summary: | The remote host is running one of the Microsoft Windows operating systems. It was possible to log into it using a NULL session. A NULL session (no login/password) allows to get information about the remote host. |
| Solution: | Disabling Logging of Anonymous Logon Events (on Windows XP and later) You can completely disable anonymous logons (aka NULL sessions), but doing so might affect accessibility by users in trusting domains. Before changing policies throughout your domain, we suggest testing them on a limited number of systems. Windows XP and later provide the six policies listed below for controlling what information can be accessed anonymously. (These policies are in the Microsoft Management Console-MMC-Local Security Policy snap-in under Computer Configuration\Windows Settings\SecuritySettings\Local Policies\SecurityOptions.)
The default values for these policies are acceptable for servers on a typical internal LAN. For hardened servers, such as Internet servers, we recommend disabling policies 1 and 4, enabling policies 2 and 3, and specifying empty lists for policies 5 and 6. |
| CVE: | |
| Nist NVD (CVSS): | AV:N/AC:L/Au:N/C:P/I:P/A:P |
| CVSS Score: | 7.5 |
Scanning For and Finding Vulnerabilities in NULL Session Available (SMB)
Use of Vulnerability Management tools, like Fortra Vulnerability Management (Fortra VM), 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.
Penetration Testing (pentest) for this Vulnerability
The Vulnerabilities in NULL Session Available (SMB) is prone to false positive reports by most vulnerability assessment solutions. Fortra VM uses 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 NULL Session Available (SMB) 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.
Security Updates on Vulnerabilities in NULL Session Available (SMB)
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.
Disclosures related to this vulnerability
https://nmap.org/nsedoc/lib/smb.html
Patching/Repairing this Vulnerability
https://msdn.microsoft.com/en-us/library/ms913275(v=winembedded.5).aspx
Vulnerabilities in NULL Session Available (SMB) is a Low 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.
Exploits related to Vulnerabilities in NULL Session Available (SMB)
- https://www.dummies.com/programming/networking/null-session-attacks-and-how-to-avoid-them/
- https://searchenterprisedesktop.techtarget.com/tip/Null-session-attacks-Whos-still-vulnerable
- https://security.stackexchange.com/questions/81845/smb-cifs-shares-on-hp-ux-vulnerabilities