Detection rules › Splunk
CSC Execution (EDR)
CSC.exe is a binary file used by .NET to compile C# code. Adversaries may attempt to make payloads difficult to discover and analyze by delivering files to victims as uncompiled code
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Stealth | T1027.004 Obfuscated Files or Information: Compile After Delivery |
References
Event coverage
| Provider | Event | Title |
|---|---|---|
| Sysmon | Event ID 1 | Process creation |
| Security-Auditing | Event ID 4688 | A new process has been created. |
Rule body yaml
id: '6133.13849'
title: CSC Execution
description: 'CSC.exe is a binary file used by .NET to compile C# code. Adversaries
may attempt to make payloads difficult to discover and analyze by delivering files
to victims as uncompiled code. Living Off the Land Binary and Scripts (LOLBAS) (LOLBIN)
-- Software Association: Clop -- Atomics T1010 Test #1 Atomics T1127.001 Test #1'
logic_format: Splunk
logic: ' `get_endpoint_data` `get_endpoint_data_edr` ((event_type IN ("childproc","netconn","proc"))
OR (TERM(ProcessRollup2) OR Type=Process) OR TERM(DeviceProcessEvents)) (TERM(csc)
OR "csc.exe" OR TERM(cvtres) or "cvtres.exe") | table _time, host, user, signature_id,
process, process_*, parent_process_* | bin span=1s | stats values(*) as * by _time,
host `hec_collect`'
techniques:
- defense-evasion:obfuscated files or information:compile after delivery
technique_id:
- T1027.004
data_category:
- EDR Logs
references:
- https://www.clearskysec.com/wp-content/uploads/2018/11/MuddyWater-Operations-in-Lebanon-and-Oman.pdf
- https://unit42.paloaltonetworks.com/unit42-cardinal-rat-active-two-years/
Stages and Predicates
Stage 1: search
`get_endpoint_data` `get_endpoint_data_edr` ((event_type IN ("childproc","netconn","proc")) OR (TERM(ProcessRollup2) OR Type=Process) OR TERM(DeviceProcessEvents)) (TERM(csc) OR "csc.exe" OR TERM(cvtres) or "cvtres.exe")
Stage 2: table
| table _time, host, user, signature_id, process, process_*, parent_process_*
Stage 3: bucket
| bin span=1s
Stage 4: stats
| stats values(*) as * by _time, host `hec_collect`
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 |
|---|---|---|
event_type | in |
|
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 | TERM |
| 1 | ProcessRollup2 |
| 1 | TERM |
| 1 | DeviceProcessEvents |
| 1 | TERM |
| 1 | csc |
| 1 | "csc.exe" |
| 1 | TERM |
| 1 | cvtres |
| 1 | "cvtres.exe" |