Unauthorized Command Message T0855

ICS Tactic: Impair Process Control

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
DeviceProduct2eq 2iSID
EventClassID2in 2114, 115, 116, 156, 161
AlertName1contains 1function code not supported by outstation, illegal bacnet message, illegal connection attempt on port 0
EventMessage1contains 1unauthorized
ProviderName1eq 1IoTSecurity
isNew1eq 1True

Top indicator values (80 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
DeviceProducteq
iSID
28
AlertNamecontains
function code not supported by outstation
1
AlertNamecontains
illegal bacnet message
1
AlertNamecontains
illegal connection attempt on port 0
1
AlertNamecontains
illegal dnp3 operation
1
AlertNamecontains
illegal modbus operation (exception raised by master)
1
AlertNamecontains
illegal modbus operation (function code zero)
1
AlertNamecontains
illegal protocol version
1
AlertNamecontains
incorrect parameter sent to outstation
1
AlertNamecontains
initiation of an obsolete function code (initialize data)
1
AlertNamecontains
initiation of an obsolete function code (save config)
1
AlertNamecontains
modbus exception
1
AlertNamecontains
new activity detected - lontalk network variable
12
AlertNamecontains
new activity detected - ovation data request
12
AlertNamecontains
new activity detected - read/write command (ams index group)
12
AlertNamecontains
new activity detected - read/write command (ams index offset)
12
AlertNamecontains
new activity detected - unauthorized deltav message type
12
AlertNamecontains
new activity detected - unauthorized deltav roc operation
12
AlertNamecontains
new activity detected - using ams protocol command
12
AlertNamecontains
new activity detected - using siemens sicam command
12
AlertNamecontains
new activity detected - using suitelink protocol command
12
AlertNamecontains
new activity detected - using suitelink protocol sessions
12
AlertNamecontains
new activity detected - using yokogawa vnetip command
12
AlertNamecontains
omron fins unauthorized command
12
AlertNamecontains
slave device received illegal
1
AlertNamecontains
toshiba computer link unauthorized command
12
AlertNamecontains
unauthorized abb totalflow file operation
12
AlertNamecontains
unauthorized abb totalflow register operation
12
AlertNamecontains
unauthorized access to siemens s7 plus object
12
AlertNamecontains
unauthorized bacnet object access
12

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)

Kusto 3 rules