Obfuscated Files or Information: Indicator Removal from Tools T1027.005
Tactic: Stealth
Adversaries may remove indicators from tools if they believe their malicious tool was detected, quarantined, or otherwise curtailed. They can modify the tool by removing the indicator and using the updated version that is no longer detected by the target's defensive systems or subsequent targets that may use similar systems.
Events covered
5 catalog events are tagged with this technique by at least one rule.
| Provider | Event | Title |
|---|---|---|
| Sysmon | Event ID 1 | Process creation |
| Security-Auditing | Event ID 4656 | A handle to an object was requested. |
| Security-Auditing | Event ID 4658 | The handle to an object was closed. |
| Security-Auditing | Event ID 4663 | An attempt was made to access an object. |
| PowerShell | Event ID 4104 | Creating Scriptblock text (MessageNumber of MessageTotal). |
Authoring guide
Patterns shared across the 6 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 (8 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 (29 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.
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 4 rules
- HackTool - CrackMapExec PowerShell Obfuscation
- Potential Secure Deletion with SDelete
- PUA - DefenderCheck Execution
- PUA - Potential PE Metadata Tamper Using Rcedit