CVE-2020-1206 in Windows
Summary
by MITRE
An information disclosure vulnerability exists in the way that the Microsoft Server Message Block 3.1.1 (SMBv3) protocol handles certain requests, aka 'Windows SMBv3 Client/Server Information Disclosure Vulnerability'.
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Analysis
by VulDB Data Team • 10/23/2020
The CVE-2020-1206 vulnerability represents a critical information disclosure flaw within Microsoft's Server Message Block protocol version 3.1.1, commonly known as SMBv3. This vulnerability specifically affects how the SMBv3 protocol handles certain client requests, creating an avenue for unauthorized information exposure. The flaw exists in the protocol implementation that governs file sharing and network communication between Windows systems, making it particularly dangerous in enterprise environments where SMBv3 is extensively utilized. The vulnerability impacts both client and server implementations of the SMBv3 protocol, potentially allowing attackers to extract sensitive data from systems that properly authenticate but are otherwise vulnerable to this specific class of attack.
The technical nature of this vulnerability stems from improper handling of certain SMBv3 requests that contain specific parameter combinations or request structures. When a malicious actor crafts and submits specially formatted requests to an affected SMBv3 server or client, the protocol fails to properly validate or sanitize the incoming data, leading to unintended information disclosure. This behavior manifests as the protocol inadvertently exposing internal system information, memory contents, or other sensitive data that should remain protected within the secure communication boundaries. The vulnerability operates at the protocol level rather than at the application layer, making it particularly insidious as it can bypass traditional application security controls and operate within the legitimate communication channels established by the SMB protocol. According to CWE classification, this vulnerability maps to CWE-200, which covers "Information Exposure," and specifically relates to improper information handling within network protocols.
The operational impact of CVE-2020-1206 extends significantly beyond simple data exposure, as it can provide attackers with valuable reconnaissance information that facilitates more sophisticated attacks. An attacker who successfully exploits this vulnerability can potentially gather system configuration details, memory dumps, or other sensitive information that could be used to further compromise the targeted systems. The vulnerability's impact is particularly severe in environments where SMBv3 is used for file sharing, print services, or other network operations, as it can expose information about network topology, system configurations, and potentially even authentication credentials or session information. This information disclosure can serve as a foundation for privilege escalation attacks, lateral movement within networks, or other advanced persistent threat activities. The vulnerability's presence in Windows SMBv3 implementations means that organizations with multiple Windows systems communicating via SMBv3 are at risk, potentially affecting entire network infrastructures rather than isolated systems.
Organizations facing this vulnerability should implement immediate mitigations including applying the relevant Microsoft security updates that address the specific SMBv3 information disclosure issue. The vulnerability's classification under the ATT&CK framework includes techniques related to credential access and reconnaissance, specifically covering information gathering and credential dumping activities. Network segmentation and firewall rules should be implemented to restrict SMBv3 traffic where possible, particularly between sensitive internal systems and external networks. Additionally, monitoring should be enhanced to detect unusual SMBv3 request patterns that might indicate exploitation attempts. System administrators should consider disabling SMBv3 if the protocol is not essential for operations, as this provides a complete defense against exploitation of this specific vulnerability. The mitigation strategy should also include regular vulnerability assessments and penetration testing to identify any potential exploitation attempts or related vulnerabilities within the SMBv3 implementation. Organizations should also review their incident response procedures to ensure they can effectively detect and respond to information disclosure events that might result from this vulnerability.