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  1. Frameworks
  2. >ATTACK
  3. >Defense Evasion
  4. >ATTACK-T1036.007
ATTACK-T1036.007Active

Double File Extension

Statement

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: <code>File.txt.exe</code> may render in some views as just <code>File.txt</code>). 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 <code>Evil.txt.exe</code> may display as <code>Evil.txt</code> 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.

Location

Tactic
Defense Evasion

Technique Details

Identifier
ATTACK-T1036.007
Parent Technique
ATTACK-T1036
ATT&CK Page
View on MITRE

Tactics

Defense Evasion

Platforms

Windows

Detection

Detection Strategy for Double File Extension Masquerading

Mitigations

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.
SP 800-53
SP800-53-CA-7relatedvia ctid-attack-to-sp800-53
SP800-53-CM-2relatedvia ctid-attack-to-sp800-53
SP800-53-CM-6relatedvia ctid-attack-to-sp800-53
SP800-53-CM-7relatedvia ctid-attack-to-sp800-53
SP800-53-IA-2relatedvia ctid-attack-to-sp800-53
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Defense Evasion183 controls
ATTACK-T1006Direct Volume AccessATTACK-T1014RootkitATTACK-T1027Obfuscated Files or InformationATTACK-T1027.001Binary PaddingATTACK-T1027.002Software PackingATTACK-T1027.003SteganographyATTACK-T1027.004Compile After DeliveryATTACK-T1027.005Indicator Removal from ToolsATTACK-T1027.006HTML SmugglingATTACK-T1027.007Dynamic API ResolutionATTACK-T1027.008Stripped PayloadsATTACK-T1027.009Embedded PayloadsATTACK-T1027.010Command ObfuscationATTACK-T1027.011Fileless StorageATTACK-T1027.012LNK Icon SmugglingATTACK-T1027.013Encrypted/Encoded FileATTACK-T1027.014Polymorphic CodeATTACK-T1027.015CompressionATTACK-T1027.016Junk Code InsertionATTACK-T1027.017SVG SmugglingATTACK-T1036MasqueradingATTACK-T1036.001Invalid Code SignatureATTACK-T1036.002Right-to-Left OverrideATTACK-T1036.003Rename Legitimate UtilitiesATTACK-T1036.004Masquerade Task or ServiceATTACK-T1036.005Match Legitimate Resource Name or LocationATTACK-T1036.006Space after FilenameATTACK-T1036.007Double File ExtensionATTACK-T1036.008Masquerade File TypeATTACK-T1036.009Break Process TreesATTACK-T1036.010Masquerade Account NameATTACK-T1036.011Overwrite Process ArgumentsATTACK-T1036.012Browser FingerprintATTACK-T1055Process InjectionATTACK-T1055.001Dynamic-link Library InjectionATTACK-T1055.002Portable Executable InjectionATTACK-T1055.003Thread Execution HijackingATTACK-T1055.004Asynchronous Procedure CallATTACK-T1055.005Thread Local StorageATTACK-T1055.008Ptrace System CallsATTACK-T1055.009Proc MemoryATTACK-T1055.011Extra Window Memory InjectionATTACK-T1055.012Process HollowingATTACK-T1055.013Process DoppelgängingATTACK-T1055.014VDSO HijackingATTACK-T1055.015ListPlantingATTACK-T1070Indicator RemovalATTACK-T1070.001Clear Windows Event LogsATTACK-T1070.002Clear Linux or Mac System LogsATTACK-T1070.003Clear Command HistoryATTACK-T1070.004File DeletionATTACK-T1070.005Network Share Connection RemovalATTACK-T1070.006TimestompATTACK-T1070.007Clear Network Connection History and ConfigurationsATTACK-T1070.008Clear Mailbox DataATTACK-T1070.009Clear PersistenceATTACK-T1070.010Relocate MalwareATTACK-T1078Valid AccountsATTACK-T1078.001Default AccountsATTACK-T1078.002Domain AccountsATTACK-T1078.003Local AccountsATTACK-T1078.004Cloud AccountsATTACK-T1112Modify RegistryATTACK-T1127Trusted Developer Utilities Proxy ExecutionATTACK-T1127.001MSBuildATTACK-T1127.002ClickOnceATTACK-T1127.003JamPlusATTACK-T1134Access Token ManipulationATTACK-T1134.001Token Impersonation/TheftATTACK-T1134.002Create Process with TokenATTACK-T1134.003Make and Impersonate TokenATTACK-T1134.004Parent PID SpoofingATTACK-T1134.005SID-History InjectionATTACK-T1140Deobfuscate/Decode Files or InformationATTACK-T1197BITS JobsATTACK-T1202Indirect Command ExecutionATTACK-T1205Traffic SignalingATTACK-T1205.001Port KnockingATTACK-T1205.002Socket FiltersATTACK-T1207Rogue Domain ControllerATTACK-T1211Exploitation for Defense EvasionATTACK-T1216System Script Proxy ExecutionATTACK-T1216.001PubPrnATTACK-T1216.002SyncAppvPublishingServerATTACK-T1218System Binary Proxy ExecutionATTACK-T1218.001Compiled HTML FileATTACK-T1218.002Control PanelATTACK-T1218.003CMSTPATTACK-T1218.004InstallUtilATTACK-T1218.005MshtaATTACK-T1218.007MsiexecATTACK-T1218.008OdbcconfATTACK-T1218.009Regsvcs/RegasmATTACK-T1218.010Regsvr32ATTACK-T1218.011Rundll32ATTACK-T1218.012VerclsidATTACK-T1218.013MavinjectATTACK-T1218.014MMCATTACK-T1218.015Electron ApplicationsATTACK-T1220XSL Script ProcessingATTACK-T1221Template InjectionATTACK-T1222File and Directory Permissions ModificationATTACK-T1222.001Windows File and Directory Permissions ModificationATTACK-T1222.002Linux and Mac File and Directory Permissions ModificationATTACK-T1480Execution GuardrailsATTACK-T1480.001Environmental KeyingATTACK-T1480.002Mutual ExclusionATTACK-T1484Domain or Tenant Policy ModificationATTACK-T1484.001Group Policy ModificationATTACK-T1484.002Trust ModificationATTACK-T1497Virtualization/Sandbox EvasionATTACK-T1497.001System ChecksATTACK-T1497.002User Activity Based ChecksATTACK-T1497.003Time Based ChecksATTACK-T1535Unused/Unsupported Cloud RegionsATTACK-T1542Pre-OS BootATTACK-T1542.004ROMMONkitATTACK-T1542.005TFTP BootATTACK-T1548.006TCC ManipulationATTACK-T1550Use Alternate Authentication MaterialATTACK-T1550.001Application Access TokenATTACK-T1550.002Pass the HashATTACK-T1550.003Pass the TicketATTACK-T1550.004Web Session CookieATTACK-T1553Subvert Trust ControlsATTACK-T1553.001Gatekeeper BypassATTACK-T1553.002Code SigningATTACK-T1553.003SIP and Trust Provider HijackingATTACK-T1553.004Install Root CertificateATTACK-T1553.005Mark-of-the-Web BypassATTACK-T1553.006Code Signing Policy ModificationATTACK-T1562Impair DefensesATTACK-T1562.001Disable or Modify ToolsATTACK-T1562.002Disable Windows Event LoggingATTACK-T1562.003Impair Command History LoggingATTACK-T1562.004Disable or Modify System FirewallATTACK-T1562.006Indicator BlockingATTACK-T1562.007Disable or Modify Cloud FirewallATTACK-T1562.008Disable or Modify Cloud LogsATTACK-T1562.009Safe Mode BootATTACK-T1562.010Downgrade AttackATTACK-T1562.011Spoof Security AlertingATTACK-T1562.012Disable or Modify Linux Audit SystemATTACK-T1562.013Disable or Modify Network Device FirewallATTACK-T1564Hide ArtifactsATTACK-T1564.001Hidden Files and DirectoriesATTACK-T1564.002Hidden UsersATTACK-T1564.003Hidden WindowATTACK-T1564.004NTFS File AttributesATTACK-T1564.005Hidden File SystemATTACK-T1564.006Run Virtual InstanceATTACK-T1564.007VBA StompingATTACK-T1564.008Email Hiding RulesATTACK-T1564.009Resource ForkingATTACK-T1564.010Process Argument SpoofingATTACK-T1564.011Ignore Process InterruptsATTACK-T1564.012File/Path ExclusionsATTACK-T1564.013Bind MountsATTACK-T1564.014Extended AttributesATTACK-T1578Modify Cloud Compute InfrastructureATTACK-T1578.001Create SnapshotATTACK-T1578.002Create Cloud InstanceATTACK-T1578.003Delete Cloud InstanceATTACK-T1578.004Revert Cloud InstanceATTACK-T1578.005Modify Cloud Compute ConfigurationsATTACK-T1599Network Boundary BridgingATTACK-T1599.001Network Address Translation TraversalATTACK-T1600Weaken EncryptionATTACK-T1600.001Reduce Key SpaceATTACK-T1600.002Disable Crypto HardwareATTACK-T1601Modify System ImageATTACK-T1601.001Patch System ImageATTACK-T1601.002Downgrade System ImageATTACK-T1610Deploy ContainerATTACK-T1612Build Image on HostATTACK-T1620Reflective Code LoadingATTACK-T1622Debugger EvasionATTACK-T1647Plist File ModificationATTACK-T1656ImpersonationATTACK-T1666Modify Cloud Resource HierarchyATTACK-T1672Email SpoofingATTACK-T1678Delay ExecutionATTACK-T1679Selective Exclusion