Detection rules › Splunk
regsvr32 Execution (Sysmon)
Using regsvr32.exe, an adversary may load malicious .dll files
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Stealth |
References
Telemetry coverage
| Provider | Record / event type |
|---|---|
| Sysmon | Event ID 1: Process creation |
Rule body
id: '5977.18111'
title: regsvr32 Execution
description: 'Using regsvr32.exe, an adversary may load malicious .dll files. -- Living
Off the Land Binary and Scripts (LOLBAS) (LOLBIN) -- Threat Actor Association: Kimsuky,
TA551, Traveling Spider, Wizard Spider -- Software Association: Astaroth, Bazar,
Black Basta, Conti, HermeticWizard, IcedID, Nefilim, Qakbot/Qbot, Rhysida, XingLocker,
Zloader Atomics T1218.010 Test#1 Atomics T1218.010 Test#2 Atomics T1218.010 Test#3
Atomics T1218.010 Test#4 Atomics T1218.010 Test#5'
logic_format: Splunk
logic: '`get_endpoint_data` `get_endpoint_data_sysmon` (TERM(EventCode=1) OR "<EventID>1<")
TERM(regsvr32) | regex process="(?i)(regsvr32)"| table _time, host, user parent_*,
process, process_*, signature_id | bin span=1s | stats values(*) as * by _time,
host | eventstats dc(process) as dc_process by host | where dc_process < 10 '
techniques:
- defense-evasion:system binary proxy execution:regsvr32
technique_id:
- T1218.010
data_category:
- Windows Sysmon
references:
- https://lolbas-project.github.io/lolbas/Binaries/Regsvr32/
- https://www.carbonblack.com/blog/threat-advisory-squiblydoo-continues-trend-of-attackers-using-native-os-tools-to-live-off-the-land/
Stages and Predicates
Stage 1: search
`get_endpoint_data` `get_endpoint_data_sysmon` (TERM(EventCode=1) OR "<EventID>1<") TERM(regsvr32)
Stage 2: regex
| regex process="(?i)(regsvr32)"
Stage 3: table
| table _time, host, user parent_*, process, process_*, signature_id
Stage 4: bucket
| bin span=1s
Stage 5: stats
| stats values(*) as * by _time, host
Stage 6: eventstats
| eventstats dc(process) as dc_process by host
Stage 7: where
| where dc_process < 10
Indicators
These rows show field, operator, and value matches.
| Field | Kind | Values | Search |
|---|---|---|---|
EventCode | eq |
| field:"EventID" kind:eq value:"1" |
dc_process | lt |
| field:"dc_process" kind:lt value:"10" |
process | regex_match |
| field:"CommandLine" kind:regex_match |
Search terms
These SPL tokens match against raw event text.
| Stage | Term |
|---|---|
| 1 | "<EventID>1<" |
| 1 | regsvr32 |