Active Scanning T1595

Tactic: Reconnaissance

Adversaries may execute active reconnaissance scans to gather information that can be used during targeting. Active scans are those where the adversary probes victim infrastructure via network traffic, as opposed to other forms of reconnaissance that do not involve direct interaction.

Events covered

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

Authoring guide

Patterns shared across the 65 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 (106 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
EventType12eq 5, in 4, contains 3exec, flow_started, network_flow, ConnectionEvent, vcn.flowlogs
data_data_result_s10eq 10failed
data_data_severity_s10eq 10High
deviceProduct_s10eq 10azure
type10eq 10Microsoft.Compute/disks, Microsoft.Compute/virtualMachines, Microsoft.ContainerRegistry/registries, Microsoft.KeyVault/vaults, Microsoft.Network/networkSecurityGroups
sourcetype8eq 7, in 1cisco:sfw:estreamer, XmlWinEventLog, cisco:cloud_security:proxy, cisco:sdwan:access, nginx:plus:access
DestinationPort7is_not_null 3, in 2, eq 1, lt 110000, 1025, 1026, 139, 21
src_ip7is_not_null 5, in 2, cidr_match 110.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16
CommandLine4contains 3, in 1--healthcheck, --level full, --no-enum-limit, f , r
Esql.event_count4gt 3, lt 150, 5, 500
http.response.status_code4eq 2, in 2200, 403, 404, 500, 502
process_name4in 3, eq 1bash, binwalk, busybox, cewl, commix
Message3contains 2, eq 1UserSignIn, found user-agent associated with security scanner, unauthorized access attempt
dest_ip3cidr_match 2, is_not_null 110.0.0.0/8, 127.0.0.0/8, 169.254.0.0/16
event.type3eq 3start

Top indicator values (693 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
data_data_result_seq
failed
1010
data_data_severity_seq
High
1010
deviceProduct_seq
azure
1010
EventTypein
flow_started
33
EventTypein
network_flow
33
event.typeeq
start
3606
sourcetypeeq
cisco:sfw:estreamer
332
CommandLinecontains
--healthcheck
23
CommandLinecontains
--level full
23
CommandLinecontains
--no-enum-limit
23
CommandLinecontains
--scanner aclcheck
23
CommandLinecontains
--scanner antivirus
23
CommandLinecontains
--scanner computerversion
23
CommandLinecontains
--scanner foreignusers
23
CommandLinecontains
--scanner laps_bitlocker
23
CommandLinecontains
--scanner localadmin
23
CommandLinecontains
--scanner nullsession
23
CommandLinecontains
--scanner nullsession-trust
23
CommandLinecontains
--scanner oxidbindings
23
CommandLinecontains
--scanner remote
23
CommandLinecontains
--scanner share
23
CommandLinecontains
--scanner smb
23
CommandLinecontains
--scanner smb3querynetwork
23
CommandLinecontains
--scanner spooler
23
CommandLinecontains
--scanner startup
23
CommandLinecontains
--scanner zerologon
23
CommandLinecontains
--server
23
DestinationPortin
139
24
DestinationPortin
21
22
DestinationPortin
22
24

Exclusions (25 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
DestinationPortin
443
2
DestinationPortin
80
2
DestinationPortin
25
1
process.argswildcard
-*z*
2
process.argswildcard
127.0.0.1
2
process.argswildcard
localhost
2
process_namein
nc
2
process_namein
nc.traditional
2
process_namein
ncat
2
process_namein
netcat
2
src_ipcidr_match
10.0.0.0/8
2
src_ipcidr_match
127.0.0.0/8
2
src_ipcidr_match
169.254.0.0/16
2
src_ipcidr_match
172.16.0.0/12
2
src_ipcidr_match
192.168.0.0/16
2

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 5 rules

Elastic 17 rules

Splunk 11 rules

Kusto 25 rules

Panther 7 rules