Detection rules › Splunk
Additional dll added to Spool Driver (Sysmon)
This use case look for an additional dll to the print drivers as seen with Print Nightmare CVE-2021-1675
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Persistence | T1547 Boot or Logon Autostart Execution |
| Privilege Escalation | T1547 Boot or Logon Autostart Execution |
References
Event coverage
| Provider | Event | Title |
|---|---|---|
| Sysmon | Event ID 11 | FileCreate |
| Sysmon | Event ID 23 | FileDelete (File Delete archived) |
Rule body yaml
id: '6446.7204'
title: Additional dll added to Spool Driver
description: 'This use case look for an additional dll to the print drivers as seen
with Print Nightmare CVE-2021-1675. -- Threat Actor Association: Earth Lusca, Vice
Society - Software Association: Black Basta, Play, Ransom Cartel'
logic_format: Splunk
logic: '`get_endpoint_data` `get_endpoint_data_sysmon` ((EventCode=11 OR "<EventID>11<"
OR "<EventID>23<" OR EventCode=23) "spoolsv.exe" "dll") | regex TargetFilename="\QC:\Windows\System32\spool\drivers\x64\E"
| table _time, host, user, signature_id, process, process_*, parent_* | bin span=5s
| stats values(*) as * by _time, host, process_path | where match(signature_id,
"11") and match(signature_id, "23") '
techniques:
- persistence:boot or logon autostart execution
technique_id:
- T1547
data_category:
- Windows Sysmon
references:
- https://github.com/cube0x0/CVE-2021-1675
Stages and Predicates
Stage 1: search
`get_endpoint_data` `get_endpoint_data_sysmon` ((EventCode=11 OR "<EventID>11<" OR "<EventID>23<" OR EventCode=23) "spoolsv.exe" "dll")
Stage 2: regex
| regex TargetFilename="\QC:\Windows\System32\spool\drivers\x64\E"
Stage 3: table
| table _time, host, user, signature_id, process, process_*, parent_*
Stage 4: bucket
| bin span=5s
Stage 5: stats
| stats values(*) as * by _time, host, process_path
Stage 6: where
| where match(signature_id, "11") and match(signature_id, "23")
Indicators
Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.
| Field | Kind | Values |
|---|---|---|
EventCode | eq |
|
TargetFilename | regex_match |
|
signature_id | match |
|
Search terms
Bare-string tokens in the SPL search body. Splunk matches each token against _raw (the untyped raw event text) anywhere it appears, not against a specific field. These don't surface in the Indicators table because they aren't predicates on a known field.
| Stage | Term |
|---|---|
| 1 | "<EventID>11<" |
| 1 | "<EventID>23<" |
| 1 | "spoolsv.exe" |
| 1 | "dll" |