Modify System Image T1601

Tactic: Defense Impairment

Adversaries may make changes to the operating system of embedded network devices to weaken defenses and provide new capabilities for themselves. On such devices, the operating systems are typically monolithic and most of the device functionality and capabilities are contained within a single file.

Authoring guide

Patterns shared across the 2 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 (7 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
EventType1in 1ProcessRollup2, exec, exec_event
Message1in 1*Could not download*, *Download failed*, *Failed to download file*
event.type1eq 1start
host.os.type1eq 1
process.args1in 1--exec, --load, --unload
process_name1eq 1kexec
sourcetype1in 1vmw-syslog, vmware:esxlog*

Top indicator values (20 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
EventTypein
ProcessRollup2
1117
EventTypein
exec
1171
EventTypein
exec_event
1139
EventTypein
executed
188
EventTypein
process_started
174
EventTypein
start
1134
Messagein
*Could not download*
1
Messagein
*Download failed*
1
Messagein
*Failed to download file*
1
Messagein
*File download error*
1
event.typeeq
start
1606
process.argsin
--exec
1
process.argsin
--load
1
process.argsin
--unload
1
process.argsin
-e
1
process.argsin
-l
13
process.argsin
-u
12
process_nameeq
kexec
1
sourcetypein
vmw-syslog
123
sourcetypein
vmware:esxlog*
123

Exclusions (5 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
parent_process_namein
kdumpctl
1
parent_process_namein
unload.sh
1
process.parent.argsin
/usr/bin/kdumpctl
1
process.parent.argsin
/usr/lib/kdump/unload.sh
1
process.parent.argsin
/usr/sbin/kdump-config
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)

Elastic 1 rule

Splunk 1 rule