Obfuscated Files or Information (T1027)

Obfuscated Files or Information [T1027]

Information

Name: Obfuscated Files or Information
ID: T1027
Tactics:
Sub-Technique: T1027.011, T1027.009, T1027.013, T1027.008, , T1027.012, T1027.005, T1027.014, , , , T1027.010, , T1027.007

Introduction

Obfuscated Files or Information is a recognized technique within the MITRE ATT&CK framework (T1027), categorized under defense evasion tactics. Attackers utilize obfuscation to disguise malicious content, code, or commands, making it challenging for security systems and analysts to detect or interpret malicious behavior. Obfuscation techniques include encoding, encryption, packing, compression, or deliberately obscuring code logic to evade detection mechanisms and complicate forensic analysis.

Deep Dive Into Technique

Obfuscation involves deliberately altering data, code, or scripts to conceal their true functionality and evade detection by security tools and analysts. Attackers commonly use several methods:

Encoding and Encryption:
- Base64 encoding, XOR encoding, or custom encryption algorithms to hide scripts, payloads, or commands.
- Encrypted payloads that decrypt at runtime, commonly seen in PowerShell scripts or macros.
Packing and Compression:
- Executable packers (e.g., UPX, ASPack) compress or encrypt executable files to evade antivirus detection.
- Compressed archives (e.g., ZIP, RAR) with password protection or nested compression layers.
Code Obfuscation:
- Renaming variables, functions, and classes to nonsensical or random strings.
- Adding redundant, meaningless, or misleading code to confuse analysis.
- Using reflection or dynamic code execution to obscure the actual flow of execution.
Steganography:
- Concealing malicious payloads within legitimate files such as images, audio, or video files.
- Extracting payloads at runtime using specialized decoding or extraction methods.
Fileless Techniques:
- Injecting obfuscated scripts or commands directly into memory, registry entries, or legitimate processes without writing files to disk.
- Leveraging legitimate system tools (e.g., PowerShell, WScript, Certutil) to decode and execute obfuscated payloads.

Attackers frequently combine multiple obfuscation techniques to maximize their chances of bypassing security controls and detection.

When this Technique is Usually Used

Obfuscated Files or Information appear across various stages of cyberattacks, including:

Initial Access:
- Phishing emails with obfuscated attachments or links to evade email filters.
- Malicious documents containing macros or embedded scripts encoded to bypass antivirus scans.
Execution:
- Running obfuscated scripts or binaries to execute malicious payloads without detection.
- Leveraging encoded PowerShell or JavaScript commands to evade endpoint detection and response (EDR) tools.
Persistence and Privilege Escalation:
- Obfuscated scripts or registry keys that execute upon system startup or user login.
- Hidden, encoded payloads that trigger privilege escalation exploits.
Defense Evasion:
- Obfuscation to hide malware from antivirus, sandbox analysis, heuristic detection, or static analysis tools.
- Using fileless malware techniques to avoid filesystem-based detection.
Command and Control (C2):
- Encrypted or encoded network traffic to disguise communication with command and control servers.
- Steganographic techniques to embed C2 instructions within seemingly benign files or protocols.

How this Technique is Usually Detected

Detection of obfuscated files or information typically involves multiple approaches, including:

Behavioral Analysis:
- Monitoring process behavior and memory activities for unusual decoding or unpacking routines.
- Identifying suspicious API calls related to memory allocation, file extraction, or runtime compilation.
Static File Analysis:
- Scanning files for known packer signatures or unusual entropy levels indicating compression or encryption.
- Detecting excessive use of encoding functions (e.g., Base64, XOR) within scripts or binaries.
Dynamic Analysis and Sandboxing:
- Executing suspicious files in controlled environments to observe runtime behavior and payload extraction.
- Monitoring sandbox environments for unusual network traffic, file creation, or process injection.
Network Traffic Analysis:
- Identifying anomalous encrypted or encoded network traffic patterns.
- Detecting steganographic payloads embedded within otherwise legitimate network data streams.
Endpoint Detection and Response (EDR) Tools:
- Utilizing EDR solutions to monitor and detect obfuscated or encoded command execution (e.g., PowerShell encoded commands).
- Implementing detection rules or signatures targeting common obfuscation tools and techniques.
Indicators of Compromise (IoCs):
- High entropy files or binaries indicative of packing or encryption.
- Suspicious file extensions or naming conventions (e.g., .ps1, .vbs, .js, .hta) combined with unusual encoding patterns.
- Known packer signatures (e.g., UPX, MPRESS, Themida).
- Suspicious registry keys or scheduled tasks containing encoded commands.

Why it is Important to Detect This Technique

Detecting obfuscated files or information is critical because failing to do so can lead to severe consequences, including:

Prolonged Persistence:
- Obfuscated malware or scripts can remain undetected for extended periods, allowing attackers prolonged access and control over compromised systems.
Increased Difficulty of Incident Response:
- Obfuscation complicates forensic analysis and incident response efforts, increasing the time and resources required to remediate incidents.
Data Exfiltration and Espionage:
- Attackers can leverage obfuscation to discreetly exfiltrate sensitive data, intellectual property, or confidential information without detection.
Deployment of Additional Malware:
- Obfuscated payloads can deliver secondary malware, including ransomware, remote access trojans, or credential stealers, escalating the severity of an attack.
Evasion of Security Controls:
- Obfuscation techniques help malware bypass traditional antivirus, intrusion detection systems (IDS), and endpoint protection solutions, reducing overall security posture effectiveness.

Early detection and remediation of obfuscated files or information significantly reduce the potential impact, minimizing damage and preventing attackers from achieving their objectives.

Examples

Real-world examples involving obfuscated files or information include:

Emotet Malware Campaigns:
- Attackers delivered Emotet malware through heavily obfuscated macro-enabled Word documents sent via phishing emails.
- Emotet utilized Base64 encoding, PowerShell scripts, and dynamic execution techniques to evade detection and deliver secondary payloads, such as TrickBot and Ryuk ransomware.
- Impact: Massive financial losses, data breaches, and operational disruption across various industries.
APT29 (Cozy Bear) SolarWinds Attack:
- Attackers embedded obfuscated malicious code into legitimate SolarWinds software updates, enabling stealthy distribution to numerous organizations.
- The malware used sophisticated obfuscation and encoding methods to evade detection by endpoint security solutions, allowing attackers prolonged access to victim networks.
- Impact: Extensive espionage, data exfiltration, and compromise of multiple high-profile organizations and government agencies.
FIN7 Group Attacks:
- FIN7 attackers leveraged obfuscated JavaScript and VBScript payloads embedded in phishing emails to deliver malware such as Carbanak.
- The group extensively utilized encoding, packing, and obfuscated scripts to bypass email security gateways and endpoint antivirus solutions.
- Impact: Large-scale financial theft, credit card data breaches, and compromise of retail and hospitality sectors.
TrickBot Malware:
- TrickBot utilized encoded PowerShell commands and obfuscated scripts to download and execute secondary payloads, such as ransomware.
- Attackers employed multiple layers of obfuscation, including Base64 encoding, XOR encryption, and dynamic code execution to evade detection.
- Impact: Financial losses, ransomware attacks, and data theft incidents across multiple industries.
Magecart Attacks:
- Attackers obfuscated JavaScript skimmers injected into legitimate e-commerce websites to steal credit card data from customers.
- Encoding and minification techniques were used to hide malicious scripts from web security scanners and analysts.
- Impact: Massive theft of payment card data, financial losses, and reputational damage for affected businesses.

Last updated 6 hours ago

Introduction

Deep Dive Into Technique

Obfuscation involves deliberately altering data, code, or scripts to conceal their true functionality and evade detection by security tools and analysts. Attackers commonly use several methods:

Encoding and Encryption:

Base64 encoding, XOR encoding, or custom encryption algorithms to hide scripts, payloads, or commands.
Encrypted payloads that decrypt at runtime, commonly seen in PowerShell scripts or macros.

Packing and Compression:

Executable packers (e.g., UPX, ASPack) compress or encrypt executable files to evade antivirus detection.
Compressed archives (e.g., ZIP, RAR) with password protection or nested compression layers.

Code Obfuscation:

Renaming variables, functions, and classes to nonsensical or random strings.
Adding redundant, meaningless, or misleading code to confuse analysis.
Using reflection or dynamic code execution to obscure the actual flow of execution.

Steganography:

Concealing malicious payloads within legitimate files such as images, audio, or video files.
Extracting payloads at runtime using specialized decoding or extraction methods.

Fileless Techniques:

Injecting obfuscated scripts or commands directly into memory, registry entries, or legitimate processes without writing files to disk.
Leveraging legitimate system tools (e.g., PowerShell, WScript, Certutil) to decode and execute obfuscated payloads.

Attackers frequently combine multiple obfuscation techniques to maximize their chances of bypassing security controls and detection.

When this Technique is Usually Used

Obfuscated Files or Information appear across various stages of cyberattacks, including:

Initial Access:

Phishing emails with obfuscated attachments or links to evade email filters.
Malicious documents containing macros or embedded scripts encoded to bypass antivirus scans.

Execution:

Running obfuscated scripts or binaries to execute malicious payloads without detection.
Leveraging encoded PowerShell or JavaScript commands to evade endpoint detection and response (EDR) tools.

Persistence and Privilege Escalation:

Obfuscated scripts or registry keys that execute upon system startup or user login.
Hidden, encoded payloads that trigger privilege escalation exploits.

Defense Evasion:

Obfuscation to hide malware from antivirus, sandbox analysis, heuristic detection, or static analysis tools.
Using fileless malware techniques to avoid filesystem-based detection.

Command and Control (C2):

Encrypted or encoded network traffic to disguise communication with command and control servers.
Steganographic techniques to embed C2 instructions within seemingly benign files or protocols.

How this Technique is Usually Detected

Detection of obfuscated files or information typically involves multiple approaches, including:

Behavioral Analysis:

Monitoring process behavior and memory activities for unusual decoding or unpacking routines.
Identifying suspicious API calls related to memory allocation, file extraction, or runtime compilation.

Static File Analysis:

Scanning files for known packer signatures or unusual entropy levels indicating compression or encryption.
Detecting excessive use of encoding functions (e.g., Base64, XOR) within scripts or binaries.

Dynamic Analysis and Sandboxing:

Executing suspicious files in controlled environments to observe runtime behavior and payload extraction.
Monitoring sandbox environments for unusual network traffic, file creation, or process injection.

Network Traffic Analysis:

Identifying anomalous encrypted or encoded network traffic patterns.
Detecting steganographic payloads embedded within otherwise legitimate network data streams.

Endpoint Detection and Response (EDR) Tools:

Utilizing EDR solutions to monitor and detect obfuscated or encoded command execution (e.g., PowerShell encoded commands).
Implementing detection rules or signatures targeting common obfuscation tools and techniques.

Indicators of Compromise (IoCs):

High entropy files or binaries indicative of packing or encryption.
Suspicious file extensions or naming conventions (e.g., .ps1, .vbs, .js, .hta) combined with unusual encoding patterns.
Known packer signatures (e.g., UPX, MPRESS, Themida).
Suspicious registry keys or scheduled tasks containing encoded commands.

Why it is Important to Detect This Technique

Detecting obfuscated files or information is critical because failing to do so can lead to severe consequences, including:

Prolonged Persistence:

Obfuscated malware or scripts can remain undetected for extended periods, allowing attackers prolonged access and control over compromised systems.

Increased Difficulty of Incident Response:

Obfuscation complicates forensic analysis and incident response efforts, increasing the time and resources required to remediate incidents.

Data Exfiltration and Espionage:

Attackers can leverage obfuscation to discreetly exfiltrate sensitive data, intellectual property, or confidential information without detection.

Deployment of Additional Malware:

Obfuscated payloads can deliver secondary malware, including ransomware, remote access trojans, or credential stealers, escalating the severity of an attack.

Evasion of Security Controls:

Obfuscation techniques help malware bypass traditional antivirus, intrusion detection systems (IDS), and endpoint protection solutions, reducing overall security posture effectiveness.

Early detection and remediation of obfuscated files or information significantly reduce the potential impact, minimizing damage and preventing attackers from achieving their objectives.

Examples

Real-world examples involving obfuscated files or information include:

Emotet Malware Campaigns:

Attackers delivered Emotet malware through heavily obfuscated macro-enabled Word documents sent via phishing emails.
Emotet utilized Base64 encoding, PowerShell scripts, and dynamic execution techniques to evade detection and deliver secondary payloads, such as TrickBot and Ryuk ransomware.
Impact: Massive financial losses, data breaches, and operational disruption across various industries.

APT29 (Cozy Bear) SolarWinds Attack:

Attackers embedded obfuscated malicious code into legitimate SolarWinds software updates, enabling stealthy distribution to numerous organizations.
The malware used sophisticated obfuscation and encoding methods to evade detection by endpoint security solutions, allowing attackers prolonged access to victim networks.
Impact: Extensive espionage, data exfiltration, and compromise of multiple high-profile organizations and government agencies.

FIN7 Group Attacks:

FIN7 attackers leveraged obfuscated JavaScript and VBScript payloads embedded in phishing emails to deliver malware such as Carbanak.
The group extensively utilized encoding, packing, and obfuscated scripts to bypass email security gateways and endpoint antivirus solutions.
Impact: Large-scale financial theft, credit card data breaches, and compromise of retail and hospitality sectors.

TrickBot Malware:

TrickBot utilized encoded PowerShell commands and obfuscated scripts to download and execute secondary payloads, such as ransomware.
Attackers employed multiple layers of obfuscation, including Base64 encoding, XOR encryption, and dynamic code execution to evade detection.
Impact: Financial losses, ransomware attacks, and data theft incidents across multiple industries.

Magecart Attacks:

Attackers obfuscated JavaScript skimmers injected into legitimate e-commerce websites to steal credit card data from customers.
Encoding and minification techniques were used to hide malicious scripts from web security scanners and analysts.
Impact: Massive theft of payment card data, financial losses, and reputational damage for affected businesses.