Masquerading: Space after Filename T1036.006

Tactic: Stealth

Adversaries can hide a program's true filetype by changing the extension of a file. With certain file types (specifically this does not work with .app extensions), appending a space to the end of a filename will change how the file is processed by the operating system.

Events covered

1 catalog event is tagged with this technique by at least one rule.

ProviderEventTitle
ESFexecProcess Execution (Notify)

Authoring guide

Patterns shared across the 3 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 (6 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.

FieldRulesHowSample values
Image2ends_with 1, match 1 , /[a-z0-9\s_\-\\./]+\s
event.type2eq 2start
CommandLine1ends_with 1
EventType1in 1exec, exec_event, executed
host.os.type1eq 1
process_name1ends_with 1

Top indicator values (9 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.

FieldKindValueRules (here)Corpus reach
event.typeeq
start
2606
CommandLineends_with
1
EventTypein
exec
1171
EventTypein
exec_event
1139
EventTypein
executed
188
EventTypein
process_started
174
Imageends_with
1
Imagematch
/[a-z0-9\s_\-\\./]+\s
1
process_nameends_with
1

Exclusions (12 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.

FieldKindValueRules excluding
Imagestarts_with
/opt/gitlab/sv/gitlab-exporter/
1
Imagestarts_with
/opt/nessus_agent/
1
Imagestarts_with
/tmp/ansible-admin/
1
process.argseq
runc
1
process.parent.argsin
./check_rubrik
1
process.parent.argsin
/etc/rubrik/start_stop_agent.sh
1
process.parent.argsin
/etc/rubrik/start_stop_bootstrap.sh
1
process.parent.argsin
/usr/bin/check_mk_agent
1
process_namein
find
1
process_namein
grep
1
process_namein
ls
1
process_namein
xkbcomp
1

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.

Platform (all)
Domain (all)

Sigma 1 rule

Elastic 2 rules