Authentication / SMB Signing Not Required

Description

SMB Signing not required (CWE-308) is a type of authentication vulnerability that occurs in IT infrastructure. It occurs when an organization fails to require SMB Signing, which is a security feature that digitally signs SMB packets. This vulnerability can be exploited by attackers who can use malicious packets to gain access to the system, bypassing the authentication measures in place. As described in the OWASP Testing Guide, "SMB Signing is a security feature that verifies the integrity of the SMB packets sent and received by the server".

Risk

This vulnerability can have serious implications for an organization's security. If exploited, attackers can gain access to sensitive information and disrupt the organization's operations. This can lead to data loss, disruption of service, and financial losses. Additionally, this type of attack can be difficult to detect and prevent.

Solution

Organizations should make sure that SMB Signing is enabled in their system and that it is configured correctly. Additionally, organizations should use an intrusion detection system to detect any suspicious activity.

Example

The following code example, taken from the CVE directory, demonstrates how an attacker can exploit this vulnerability:

$smb = New-Object System.Net.Sockets.TcpClient("192.168.56.101",445);
$stream = $smb.GetStream();
[byte[]]$bytes = 0..65535|%{0};
$sent = $stream.Write($bytes, 0, $bytes.Length);
$stream.Close();
$smb.Close();