Adversaries may gather credential material by invoking or forcing a user to automatically provide authentication information through a mechanism in which they can intercept. The Server Message Block (SMB) protocol is commonly used in Windows networks for authentication and communication between systems for access to resources and file sharing. When a Windows system attempts to connect to an SMB resource it will automatically attempt to authenticate and send credential information for the current user to the remote system.(Citation: Wikipedia Server Message Block) This behavior is typical in enterprise environments so that users do not need to enter credentials to access network resources. Web Distributed Authoring and Versioning (WebDAV) is also typically used by Windows systems as a backup protocol when SMB is blocked or fails. WebDAV is an extension of HTTP and will typically operate over TCP ports 80 and 443.(Citation: Didier Stevens WebDAV Traffic)(Citation: Microsoft Managing WebDAV Security) Adversaries may take advantage of this behavior to gain access to user account hashes through forced SMB/WebDAV authentication. An adversary can send an attachment to a user through spearphishing that contains a resource link to an external server controlled by the adversary (i.e. [Template Injection](https://attack.mitre.org/techniques/T1221)), or place a specially crafted file on navigation path for privileged accounts (e.g. .SCF file placed on desktop) or on a publicly accessible share to be accessed by victim(s). When the user's system accesses the untrusted resource, it will attempt authentication and send information, including the user's hashed credentials, over SMB to the adversary-controlled server.(Citation: GitHub Hashjacking) With access to the credential hash, an adversary can perform off-line [Brute Force](https://attack.mitre.org/techniques/T1110) cracking to gain access to plaintext credentials.(Citation: Cylance Redirect to SMB) There are several different ways this can occur.(Citation: Osanda Stealing NetNTLM Hashes) Some specifics from in-the-wild use include: * A spearphishing attachment containing a document with a resource that is automatically loaded when the document is opened (i.e. [Template Injection](https://attack.mitre.org/techniques/T1221)). The document can include, for example, a request similar to <code>file[:]//[remote address]/Normal.dotm</code> to trigger the SMB request.(Citation: US-CERT APT Energy Oct 2017) * A modified .LNK or .SCF file with the icon filename pointing to an external reference such as <code>\\[remote address]\pic.png</code> that will force the system to load the resource when the icon is rendered to repeatedly gather credentials.(Citation: US-CERT APT Energy Oct 2017) Alternatively, by leveraging the <code>EfsRpcOpenFileRaw</code> function, an adversary can send SMB requests to a remote system's MS-EFSRPC interface and force the victim computer to initiate an authentication procedure and share its authentication details. The Encrypting File System Remote Protocol (EFSRPC) is a protocol used in Windows networks for maintenance and management operations on encrypted data that is stored remotely to be accessed over a network. Utilization of <code>EfsRpcOpenFileRaw</code> function in EFSRPC is used to open an encrypted object on the server for backup or restore. Adversaries can collect this data and abuse it as part of a NTLM relay attack to gain access to remote systems on the same internal network.(Citation: Rapid7)(Citation: GitHub)
Set and enforce secure password policies for accounts to reduce the likelihood of unauthorized access. Strong password policies include enforcing password complexity, requiring regular password changes, and preventing password reuse. This mitigation can be implemented through the following measures: Windows Systems: - Use Group Policy Management Console (GPMC) to configure: - Minimum password length (e.g., 12+ characters). - Password complexity requirements. - Password history (e.g., disallow last 24 passwords). - Account lockout duration and thresholds. Linux Systems: - Configure Pluggable Authentication Modules (PAM): - Use `pam_pwquality` to enforce complexity and length requirements. - Implement `pam_tally2` or `pam_faillock` for account lockouts. - Use `pwunconv` to disable password reuse. Password Managers: - Enforce usage of enterprise password managers (e.g., Bitwarden, 1Password, LastPass) to generate and store strong passwords. Password Blacklisting: - Use tools like Have I Been Pwned password checks or NIST-based blacklist solutions to prevent users from setting compromised passwords. Regular Auditing: - Periodically audit password policies and account configurations to ensure compliance using tools like LAPS (Local Admin Password Solution) and vulnerability scanners. *Tools for Implementation* Windows: - Group Policy Management Console (GPMC): Enforce password policies. - Microsoft Local Administrator Password Solution (LAPS): Enforce random, unique admin passwords. Linux/macOS: - PAM Modules (pam_pwquality, pam_tally2, pam_faillock): Enforce password rules. - Lynis: Audit password policies and system configurations. Cross-Platform: - Password Managers (Bitwarden, 1Password, KeePass): Manage and enforce strong passwords. - Have I Been Pwned API: Prevent the use of breached passwords. - NIST SP 800-63B compliant tools: Enforce password guidelines and blacklisting.
M1037Filter Network TrafficEmploy network appliances and endpoint software to filter ingress, egress, and lateral network traffic. This includes protocol-based filtering, enforcing firewall rules, and blocking or restricting traffic based on predefined conditions to limit adversary movement and data exfiltration. This mitigation can be implemented through the following measures: Ingress Traffic Filtering: - Use Case: Configure network firewalls to allow traffic only from authorized IP addresses to public-facing servers. - Implementation: Limit SSH (port 22) and RDP (port 3389) traffic to specific IP ranges. Egress Traffic Filtering: - Use Case: Use firewalls or endpoint security software to block unauthorized outbound traffic to prevent data exfiltration and command-and-control (C2) communications. - Implementation: Block outbound traffic to known malicious IPs or regions where communication is unexpected. Protocol-Based Filtering: - Use Case: Restrict the use of specific protocols that are commonly abused by adversaries, such as SMB, RPC, or Telnet, based on business needs. - Implementation: Disable SMBv1 on endpoints to prevent exploits like EternalBlue. Network Segmentation: - Use Case: Create network segments for critical systems and restrict communication between segments unless explicitly authorized. - Implementation: Implement VLANs to isolate IoT devices or guest networks from core business systems. Application Layer Filtering: - Use Case: Use proxy servers or Web Application Firewalls (WAFs) to inspect and block malicious HTTP/S traffic. - Implementation: Configure a WAF to block SQL injection attempts or other web application exploitation techniques.
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