Deobfuscate/Decode Files or Information T1140

Events covered

12 catalog events are tagged with this technique by at least one rule.

Authoring guide

Patterns shared across the 79 rules above: which fields they filter on, what specific values they look for, and what they exclude. The catalog normalizes field names across vendors so Sigma's Image, Elastic's process.name, and Splunk's process_name collapse into one row. Each rule contributes at most once per row.

Fields filtered most (56 distinct)

The fields most rules look at when detecting this technique. The How column shows the operators authors use (eq, wildcard, regex_match, match) and how often each appears. Sample values are concrete examples to start from, not an exhaustive list.

Top indicator values (801 distinct)

Specific (field, operator, value) combinations the rules check for, ranked by how many rules under this technique use each one. The Corpus reach column counts how many rules across the entire catalog (any technique) check the same combination. High numbers point to widely-used indicators that are likely noisy on their own; combine them with another condition for useful signal. Blank means the combination is specific to rules under this technique. Click a value to expand the rules under this technique that use it.

Exclusions (129 distinct)

Field/operator/value combinations excluded by rules under this technique (top-level not() clauses), sorted by how many rules exclude each. These are the false-positive paths the community has learned to filter out. A new rule that ignores the high-count entries here will likely fire on the same noisy paths. Click a value to expand the rules under this technique that exclude it.

Rules under this technique

Every rule in the catalog tagged with this technique, grouped by vendor. Click a rule title for its full predicates, exclusions, and indicators.

Sigma 20 rules

• Base64 Encoded PowerShell Command Detected
• Certutil payload obfuscation (command)
• Certutil payload obfuscation - Tchopper (command)
• DNS-over-HTTPS Enabled by Registry
• Linux Base64 Encoded Pipe to Shell
• Linux Base64 Encoded Shebang In CLI
• Linux Shell Pipe to Shell
• MSHTA Execution with Suspicious File Extensions
• Payload Decoded and Decrypted via Built-in Utilities
• Ping Hex IP
• Potential Base64 Decoded From Images
• Potential BlackByte Ransomware Activity
• Potential Commandline Obfuscation Using Escape Characters
• PowerShell Base64 Encoded FromBase64String Cmdlet
• PowerShell Decompress Commands
• Suspicious Inbox Manipulation Rules
• Suspicious XOR Encoded PowerShell Command
• UNC4841 - Download Compressed Files From Temp.sh Using Wget
• UNC4841 - Download Tar File From Untrusted Direct IP Via Wget
• UNC4841 - SSL Certificate Exfiltration Via Openssl

Elastic 40 rules

• Base16 or Base32 Encoding/Decoding Activity
• Base64 Decoded Payload Piped to Interpreter
• Binary Content Copy via Cmd.exe
• Command Line Obfuscation via Whitespace Padding
• Decoded Payload Piped to Interpreter Detected via Defend for Containers
• Deprecated - Encoded Executable Stored in the Registry
• Deprecated - Potential PowerShell Obfuscated Script
• Dynamic IEX Reconstruction via Method String Access
• Encoded Payload Detected via Defend for Containers
• Execution via OpenClaw Agent
• Kernel Unpacking Activity
• Long Base64 Encoded Command via Scripting Interpreter
• Multi-Base64 Decoding Attempt from Suspicious Location
• Potential Dynamic IEX Reconstruction via Environment Variables
• Potential Hex Payload Execution via Command-Line
• Potential Hex Payload Execution via Common Utility
• Potential PowerShell Obfuscated Script via High Entropy
• Potential PowerShell Obfuscation via Backtick-Escaped Variable Expansion
• Potential PowerShell Obfuscation via Character Array Reconstruction
• Potential PowerShell Obfuscation via Concatenated Dynamic Command Invocation
• Potential PowerShell Obfuscation via High Numeric Character Proportion
• Potential PowerShell Obfuscation via High Special Character Proportion
• Potential PowerShell Obfuscation via Invalid Escape Sequences
• Potential PowerShell Obfuscation via Reverse Keywords
• Potential PowerShell Obfuscation via Special Character Overuse
• Potential PowerShell Obfuscation via String Concatenation
• Potential PowerShell Obfuscation via String Reordering
• PowerShell Obfuscation via Negative Index String Reversal
• PowerShell Script with Encryption/Decryption Capabilities
• PowerShell Suspicious Payload Encoded and Compressed
• ROT Encoded Python Script Execution
• Suspicious .NET Reflection via PowerShell
• Suspicious CertUtil Commands
• Suspicious Content Extracted or Decompressed via Funzip
• Suspicious Echo or Printf Execution Detected via Defend for Containers
• Suspicious Execution from Foomatic-rip or Cupsd Parent
• Suspicious Interpreter Execution Detected via Defend for Containers
• Suspicious Windows Powershell Arguments
• Unusual Base64 Encoding/Decoding Activity
• Web Server Potential Command Injection Request

Splunk 6 rules

• Certutil De-Obfuscate_Decode Files (Sysmon)
• Certutil De-Obfuscate_Decode Files (Windows Event Log)
• Certutil Execution (Sysmon)
• Certutil Execution (Windows Event Log)
• CertUtil With Decode Argument
• Linux Auditd Base64 Decode Files

Kusto 12 rules

• A host is potentially running PowerShell to send HTTP(S) requests (ASIM Web Session schema)
• Base64 encoded Windows process command-lines
• Base64 encoded Windows process command-lines (Normalized Process Events)
• Dynatrace - Problem detection
• Dynatrace Application Security - Code-Level runtime vulnerability detection
• Dynatrace Application Security - Non-critical runtime vulnerability detection
• Dynatrace Application Security - Third-Party runtime vulnerability detection
• Ingress Tool Transfer - Certutil
• NRT Base64 Encoded Windows Process Command-lines
• NRT Process executed from binary hidden in Base64 encoded file
• Process executed from binary hidden in Base64 encoded file
• Qakbot Discovery Activies

YARA-L 1 rule

• MITRE ATT&CK T1140 Encoded Powershell Command