Masquerading: Двойное расширение файла
Other sub-techniques of Masquerading (11)
Adversaries may abuse a double extension in the filename as a means of masquerading the true file type. A file name may include a secondary file type extension that may cause only the first extension to be displayed (ex: File.txt.exe
may render in some views as just File.txt
). However, the second extension is the true file type that determines how the file is opened and executed. The real file extension may be hidden by the operating system in the file browser (ex: explorer.exe), as well as in any software configured using or similar to the system’s policies.(Citation: PCMag DoubleExtension)(Citation: SOCPrime DoubleExtension)
Adversaries may abuse double extensions to attempt to conceal dangerous file types of payloads. A very common usage involves tricking a user into opening what they think is a benign file type but is actually executable code. Such files often pose as email attachments and allow an adversary to gain Initial Access into a user’s system via Spearphishing Attachment then User Execution. For example, an executable file attachment named Evil.txt.exe
may display as Evil.txt
to a user. The user may then view it as a benign text file and open it, inadvertently executing the hidden malware.(Citation: SOCPrime DoubleExtension)
Common file types, such as text files (.txt, .doc, etc.) and image files (.jpg, .gif, etc.) are typically used as the first extension to appear benign. Executable extensions commonly regarded as dangerous, such as .exe, .lnk, .hta, and .scr, often appear as the second extension and true file type.
Примеры процедур |
|
Название | Описание |
---|---|
DarkGate |
DarkGate masquerades malicious LNK files as PDF objects using the double extension |
Bazar |
The Bazar loader has used dual-extension executable files such as PreviewReport.DOC.exe.(Citation: Cybereason Bazar July 2020) |
Mustang Panda |
Mustang Panda has used an additional filename extension to hide the true file type.(Citation: Crowdstrike MUSTANG PANDA June 2018)(Citation: Anomali MUSTANG PANDA October 2019) |
Milan |
Milan has used an executable named `companycatalog.exe.config` to appear benign.(Citation: ClearSky Siamesekitten August 2021) |
Контрмеры |
|
Контрмера | Описание |
---|---|
User Training |
User Training involves educating employees and contractors on recognizing, reporting, and preventing cyber threats that rely on human interaction, such as phishing, social engineering, and other manipulative techniques. Comprehensive training programs create a human firewall by empowering users to be an active component of the organization's cybersecurity defenses. This mitigation can be implemented through the following measures: Create Comprehensive Training Programs: - Design training modules tailored to the organization's risk profile, covering topics such as phishing, password management, and incident reporting. - Provide role-specific training for high-risk employees, such as helpdesk staff or executives. Use Simulated Exercises: - Conduct phishing simulations to measure user susceptibility and provide targeted follow-up training. - Run social engineering drills to evaluate employee responses and reinforce protocols. Leverage Gamification and Engagement: - Introduce interactive learning methods such as quizzes, gamified challenges, and rewards for successful detection and reporting of threats. Incorporate Security Policies into Onboarding: - Include cybersecurity training as part of the onboarding process for new employees. - Provide easy-to-understand materials outlining acceptable use policies and reporting procedures. Regular Refresher Courses: - Update training materials to include emerging threats and techniques used by adversaries. - Ensure all employees complete periodic refresher courses to stay informed. Emphasize Real-World Scenarios: - Use case studies of recent attacks to demonstrate the consequences of successful phishing or social engineering. - Discuss how specific employee actions can prevent or mitigate such attacks. |
Operating System Configuration |
Operating System Configuration involves adjusting system settings and hardening the default configurations of an operating system (OS) to mitigate adversary exploitation and prevent abuse of system functionality. Proper OS configurations address security vulnerabilities, limit attack surfaces, and ensure robust defense against a wide range of techniques. This mitigation can be implemented through the following measures: Disable Unused Features: - Turn off SMBv1, LLMNR, and NetBIOS where not needed. - Disable remote registry and unnecessary services. Enforce OS-level Protections: - Enable Data Execution Prevention (DEP), Address Space Layout Randomization (ASLR), and Control Flow Guard (CFG) on Windows. - Use AppArmor or SELinux on Linux for mandatory access controls. Secure Access Settings: - Enable User Account Control (UAC) for Windows. - Restrict root/sudo access on Linux/macOS and enforce strong permissions using sudoers files. File System Hardening: - Implement least-privilege access for critical files and system directories. - Audit permissions regularly using tools like icacls (Windows) or getfacl/chmod (Linux/macOS). Secure Remote Access: - Restrict RDP, SSH, and VNC to authorized IPs using firewall rules. - Enable NLA for RDP and enforce strong password/lockout policies. Harden Boot Configurations: - Enable Secure Boot and enforce UEFI/BIOS password protection. - Use BitLocker or LUKS to encrypt boot drives. Regular Audits: - Periodically audit OS configurations using tools like CIS Benchmarks or SCAP tools. *Tools for Implementation* Windows: - Microsoft Group Policy Objects (GPO): Centrally enforce OS security settings. - Windows Defender Exploit Guard: Built-in OS protection against exploits. - CIS-CAT Pro: Audit Windows security configurations based on CIS Benchmarks. Linux/macOS: - AppArmor/SELinux: Enforce mandatory access controls. - Lynis: Perform comprehensive security audits. - SCAP Security Guide: Automate configuration hardening using Security Content Automation Protocol. Cross-Platform: - Ansible or Chef/Puppet: Automate configuration hardening at scale. - OpenSCAP: Perform compliance and configuration checks. |
Обнаружение
Monitor for files written to disk that contain two file extensions, particularly when the second is an executable.(Citation: Seqrite DoubleExtension)
Ссылки
- Seqrite. (n.d.). How to avoid dual attack and vulnerable files with double extension?. Retrieved July 27, 2021.
- PCMag. (n.d.). Encyclopedia: double extension. Retrieved August 4, 2021.
- Eugene Tkachenko. (2020, May 1). Rule of the Week: Possible Malicious File Double Extension. Retrieved July 27, 2021.
- Ernesto Fernández Provecho, Pham Duy Phuc, Ciana Driscoll & Vinoo Thomas. (2023, November 21). The Continued Evolution of the DarkGate Malware-as-a-Service. Retrieved February 9, 2024.
- Chris Hoffman. (2017, March 8). How to Make Windows Show File Extensions. Retrieved August 4, 2021.
- Cybereason Nocturnus. (2020, July 16). A BAZAR OF TRICKS: FOLLOWING TEAM9’S DEVELOPMENT CYCLES. Retrieved November 18, 2020.
- Anomali Threat Research. (2019, October 7). China-Based APT Mustang Panda Targets Minority Groups, Public and Private Sector Organizations. Retrieved April 12, 2021.
- Meyers, A. (2018, June 15). Meet CrowdStrike’s Adversary of the Month for June: MUSTANG PANDA. Retrieved April 12, 2021.
- ClearSky Cyber Security . (2021, August). New Iranian Espionage Campaign By “Siamesekitten” - Lyceum. Retrieved June 6, 2022.
Связанные риски
Каталоги
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