Adversaries may abuse dynamic-link library files (DLLs) in order to achieve persistence, escalate privileges, and evade defenses. DLLs are libraries that contain code and data that can be simultaneously utilized by multiple programs. While DLLs are not malicious by nature, they can be abused through mechanisms such as side-loading, hijacking search order, and phantom DLL hijacking.(Citation: unit 42) Specific ways DLLs are abused by adversaries include: ### DLL Sideloading Adversaries may execute their own malicious payloads by side-loading DLLs. Side-loading involves hijacking which DLL a program loads by planting and then invoking a legitimate application that executes their payload(s). Side-loading positions both the victim application and malicious payload(s) alongside each other. Adversaries likely use side-loading as a means of masking actions they perform under a legitimate, trusted, and potentially elevated system or software process. Benign executables used to side-load payloads may not be flagged during delivery and/or execution. Adversary payloads may also be encrypted/packed or otherwise obfuscated until loaded into the memory of the trusted process. Adversaries may also side-load other packages, such as BPLs (Borland Package Library).(Citation: kroll bpl) Adversaries may chain DLL sideloading multiple times to fragment functionality hindering analysis. Adversaries using multiple DLL files can split the loader functions across different DLLs, with a main DLL loading the separated export functions. (Citation: Virus Bulletin) Spreading loader functions across multiple DLLs makes analysis harder, since all files must be collected to fully understand the malware’s behavior. Another method implements a “loader-for-a-loader”, where a malicious DLL’s sole role is to load a second DLL (or a chain of DLLs) that contain the real payload. (Citation: Sophos) ### DLL Search Order Hijacking Adversaries may execute their own malicious payloads by hijacking the search order that Windows uses to load DLLs. This search order is a sequence of special and standard search locations that a program checks when loading a DLL. An adversary can plant a trojan DLL in a directory that will be prioritized by the DLL search order over the location of a legitimate library. This will cause Windows to load the malicious DLL when it is called for by the victim program.(Citation: unit 42) ### DLL Redirection Adversaries may directly modify the search order via DLL redirection, which after being enabled (in the Registry or via the creation of a redirection file) may cause a program to load a DLL from a different location.(Citation: Microsoft redirection)(Citation: Microsoft - manifests/assembly) ### Phantom DLL Hijacking Adversaries may leverage phantom DLL hijacking by targeting references to non-existent DLL files. They may be able to load their own malicious DLL by planting it with the correct name in the location of the missing module.(Citation: Hexacorn DLL Hijacking)(Citation: Hijack DLLs CrowdStrike) ### DLL Substitution Adversaries may target existing, valid DLL files and substitute them with their own malicious DLLs, planting them with the same name and in the same location as the valid DLL file.(Citation: Wietze Beukema DLL Hijacking) Programs that fall victim to DLL hijacking may appear to behave normally because malicious DLLs may be configured to also load the legitimate DLLs they were meant to replace, evading defenses. Remote DLL hijacking can occur when a program sets its current directory to a remote location, such as a Web share, before loading a DLL.(Citation: dll pre load owasp)(Citation: microsoft remote preloading) If a valid DLL is configured to run at a higher privilege level, then the adversary-controlled DLL that is loaded will also be executed at the higher level. In this case, the technique could be used for privilege escalation.
Prevent the execution of unauthorized or malicious code on systems by implementing application control, script blocking, and other execution prevention mechanisms. This ensures that only trusted and authorized code is executed, reducing the risk of malware and unauthorized actions. This mitigation can be implemented through the following measures: Application Control: - Use Case: Use tools like AppLocker or Windows Defender Application Control (WDAC) to create whitelists of authorized applications and block unauthorized ones. On Linux, use tools like SELinux or AppArmor to define mandatory access control policies for application execution. - Implementation: Allow only digitally signed or pre-approved applications to execute on servers and endpoints. (e.g., `New-AppLockerPolicy -PolicyType Enforced -FilePath "C:\Policies\AppLocker.xml"`) Script Blocking: - Use Case: Use script control mechanisms to block unauthorized execution of scripts, such as PowerShell or JavaScript. Web Browsers: Use browser extensions or settings to block JavaScript execution from untrusted sources. - Implementation: Configure PowerShell to enforce Constrained Language Mode for non-administrator users. (e.g., `Set-ExecutionPolicy AllSigned`) Executable Blocking: - Use Case: Prevent execution of binaries from suspicious locations, such as `%TEMP%` or `%APPDATA%` directories. - Implementation: Block execution of `.exe`, `.bat`, or `.ps1` files from user-writable directories. Dynamic Analysis Prevention: - Use Case: Use behavior-based execution prevention tools to identify and block malicious activity in real time. - Implemenation: Employ EDR solutions that analyze runtime behavior and block suspicious code execution.
M1044Restrict Library LoadingRestricting library loading involves implementing security controls to ensure that only trusted and verified libraries (DLLs, shared objects, etc.) are loaded into processes. Adversaries often abuse Dynamic-Link Library (DLL) Injection, DLL Search Order Hijacking, or LD_PRELOAD mechanisms to execute malicious code by forcing the operating system to load untrusted libraries. This mitigation can be implemented through the following measures: Enforce Safe Library Loading Practices: - Enable `SafeDLLSearchMode` on Windows. - Restrict `LD_PRELOAD` and `LD_LIBRARY_PATH` usage on Linux systems. Code Signing Enforcement: - Require digital signatures for all libraries loaded into processes. - Use tools like Signtool, and WDAC to enforce signed DLL execution. Environment Hardening: - Secure library paths and directories to prevent adversaries from placing rogue libraries. - Monitor user-writable directories and system configurations for unauthorized changes. Audit and Monitor Library Loading: - Enable `Sysmon` on Windows to monitor for suspicious library loads. - Use `auditd` on Linux to monitor shared library paths and configuration file changes. Use Application Control Solutions: - Implement AppLocker, WDAC, or SELinux to allow only trusted libraries. *Tools for Implementation* Windows-Specific Tools: - AppLocker: Application whitelisting for DLLs. - Windows Defender Application Control (WDAC): Restrict unauthorized library execution. - Signtool: Verify and enforce code signing. - Sysmon: Monitor DLL load events (Event ID 7). Linux-Specific Tools: - auditd: Monitor changes to library paths and critical files. - SELinux/AppArmor: Define policies to restrict library loading. - ldconfig and chattr: Secure LD configuration files and prevent unauthorized modifications. Cross-Platform Solutions: - Wazuh or OSSEC: File integrity monitoring for library changes. - Tripwire: Detect and alert on unauthorized library modifications.
M1051Update SoftwareSoftware updates ensure systems are protected against known vulnerabilities by applying patches and upgrades provided by vendors. Regular updates reduce the attack surface and prevent adversaries from exploiting known security gaps. This includes patching operating systems, applications, drivers, and firmware. This mitigation can be implemented through the following measures: Regular Operating System Updates - Implementation: Apply the latest Windows security updates monthly using WSUS (Windows Server Update Services) or a similar patch management solution. Configure systems to check for updates automatically and schedule reboots during maintenance windows. - Use Case: Prevents exploitation of OS vulnerabilities such as privilege escalation or remote code execution. Application Patching - Implementation: Monitor Apache's update release notes for security patches addressing vulnerabilities. Schedule updates for off-peak hours to avoid downtime while maintaining security compliance. - Use Case: Prevents exploitation of web application vulnerabilities, such as those leading to unauthorized access or data breaches. Firmware Updates - Implementation: Regularly check the vendor’s website for firmware updates addressing vulnerabilities. Plan for update deployment during scheduled maintenance to minimize business disruption. - Use Case: Protects against vulnerabilities that adversaries could exploit to gain access to network devices or inject malicious traffic. Emergency Patch Deployment - Implementation: Use the emergency patch deployment feature of the organization's patch management tool to apply updates to all affected Exchange servers within 24 hours. - Use Case: Reduces the risk of exploitation by rapidly addressing critical vulnerabilities. Centralized Patch Management - Implementation: Implement a centralized patch management system, such as SCCM or ManageEngine, to automate and track patch deployment across all environments. Generate regular compliance reports to ensure all systems are updated. - Use Case: Streamlines patching processes and ensures no critical systems are missed. *Tools for Implementation* Patch Management Tools: - WSUS: Manage and deploy Microsoft updates across the organization. - ManageEngine Patch Manager Plus: Automate patch deployment for OS and third-party apps. - Ansible: Automate updates across multiple platforms, including Linux and Windows. Vulnerability Scanning Tools: - OpenVAS: Open-source vulnerability scanning to identify missing patches.
M1047AuditAuditing is the process of recording activity and systematically reviewing and analyzing the activity and system configurations. The primary purpose of auditing is to detect anomalies and identify potential threats or weaknesses in the environment. Proper auditing configurations can also help to meet compliance requirements. The process of auditing encompasses regular analysis of user behaviors and system logs in support of proactive security measures. Auditing is applicable to all systems used within an organization, from the front door of a building to accessing a file on a fileserver. It is considered more critical for regulated industries such as, healthcare, finance and government where compliance requirements demand stringent tracking of user and system activates.This mitigation can be implemented through the following measures: System Audit: - Use Case: Regularly assess system configurations to ensure compliance with organizational security policies. - Implementation: Use tools to scan for deviations from established benchmarks. Permission Audits: - Use Case: Review file and folder permissions to minimize the risk of unauthorized access or privilege escalation. - Implementation: Run access reviews to identify users or groups with excessive permissions. Software Audits: - Use Case: Identify outdated, unsupported, or insecure software that could serve as an attack vector. - Implementation: Use inventory and vulnerability scanning tools to detect outdated versions and recommend secure alternatives. Configuration Audits: - Use Case: Evaluate system and network configurations to ensure secure settings (e.g., disabled SMBv1, enabled MFA). - Implementation: Implement automated configuration scanning tools like SCAP (Security Content Automation Protocol) to identify non-compliant systems. Network Audits: - Use Case: Examine network traffic, firewall rules, and endpoint communications to identify unauthorized or insecure connections. - Implementation: Utilize tools such as Wireshark, or Zeek to monitor and log suspicious network behavior.
M1013Application Developer GuidanceApplication Developer Guidance focuses on providing developers with the knowledge, tools, and best practices needed to write secure code, reduce vulnerabilities, and implement secure design principles. By integrating security throughout the software development lifecycle (SDLC), this mitigation aims to prevent the introduction of exploitable weaknesses in applications, systems, and APIs. This mitigation can be implemented through the following measures: Preventing SQL Injection (Secure Coding Practice): - Implementation: Train developers to use parameterized queries or prepared statements instead of directly embedding user input into SQL queries. - Use Case: A web application accepts user input to search a database. By sanitizing and validating user inputs, developers can prevent attackers from injecting malicious SQL commands. Cross-Site Scripting (XSS) Mitigation: - Implementation: Require developers to implement output encoding for all user-generated content displayed on a web page. - Use Case: An e-commerce site allows users to leave product reviews. Properly encoding and escaping user inputs prevents malicious scripts from being executed in other users’ browsers. Secure API Design: - Implementation: Train developers to authenticate all API endpoints and avoid exposing sensitive information in API responses. - Use Case: A mobile banking application uses APIs for account management. By enforcing token-based authentication for every API call, developers reduce the risk of unauthorized access. Static Code Analysis in the Build Pipeline: - Implementation: Incorporate tools into CI/CD pipelines to automatically scan for vulnerabilities during the build process. - Use Case: A fintech company integrates static analysis tools to detect hardcoded credentials in their source code before deployment. Threat Modeling in the Design Phase: - Implementation: Use frameworks like STRIDE (Spoofing, Tampering, Repudiation, Information Disclosure, Denial of Service, Elevation of Privilege) to assess threats during application design. - Use Case: Before launching a customer portal, a SaaS company identifies potential abuse cases, such as session hijacking, and designs mitigations like secure session management. **Tools for Implementation**: - Static Code Analysis Tools: Use tools that can scan for known vulnerabilities in source code. - Dynamic Application Security Testing (DAST): Use tools like Burp Suite or OWASP ZAP to simulate runtime attacks and identify vulnerabilities. - Secure Frameworks: Recommend secure-by-default frameworks (e.g., Django for Python, Spring Security for Java) that enforce security best practices.
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