Detection rules › Splunk
Windows Visual Basic Commandline Compiler DNSQuery
The following analytic detects instances where vbc.exe, the Visual Basic Command Line Compiler, initiates DNS queries. Normally, vbc.exe operates locally to compile Visual Basic code and does not require internet access or to perform DNS lookups. Therefore, any observed DNS activity originating from vbc.exe is highly suspicious and indicative of potential malicious activity. This behavior often suggests that a malicious payload is masquerading as the legitimate vbc.exe process to establish command-and-control (C2) communication, resolve domains for data exfiltration, or download additional stages of malware. Security teams should investigate the process's parent, command-line arguments, and the resolved domains for further indicators of compromise.
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Command & Control | T1071.004 Application Layer Protocol: DNS |
Event coverage
| Provider | Event | Title |
|---|---|---|
| Sysmon | Event ID 22 | DNSEvent (DNS query) |
Rule body splunk
name: Windows Visual Basic Commandline Compiler DNSQuery
id: 8976744a-ae7a-46a4-8128-690df85c2af4
version: 6
creation_date: '2025-08-28'
modification_date: '2026-05-13'
author: Teoderick Contreras, Splunk
status: production
type: TTP
description: The following analytic detects instances where vbc.exe, the Visual Basic Command Line Compiler, initiates DNS queries. Normally, vbc.exe operates locally to compile Visual Basic code and does not require internet access or to perform DNS lookups. Therefore, any observed DNS activity originating from vbc.exe is highly suspicious and indicative of potential malicious activity. This behavior often suggests that a malicious payload is masquerading as the legitimate vbc.exe process to establish command-and-control (C2) communication, resolve domains for data exfiltration, or download additional stages of malware. Security teams should investigate the process's parent, command-line arguments, and the resolved domains for further indicators of compromise.
data_source:
- Sysmon EventID 22
search: |-
`sysmon` EventCode=22 process_name="vbc.exe"
| rename dvc as dest
| stats count min(_time) as firstTime max(_time) as lastTime
BY answer answer_count dest
process_exec process_guid process_name
query query_count reply_code_id
signature signature_id src
user_id vendor_product QueryName
QueryResults QueryStatus
| `security_content_ctime(firstTime)`
| `security_content_ctime(lastTime)`
| `windows_visual_basic_commandline_compiler_dnsquery_filter`
how_to_implement: To successfully implement this search, you need to be ingesting logs with the process name and eventcode = 22 dnsquery executions from your endpoints. If you are using Sysmon, you must have at least version 6.0.4 of the Sysmon TA. Tune and filter known instances where renamed rundll32.exe may be used.
known_false_positives: No false positives have been identified at this time.
references:
- https://www.cisa.gov/news-events/cybersecurity-advisories/aa20-266a
drilldown_searches:
- name: View the detection results for - "$dest$"
search: '%original_detection_search% | search dest = "$dest$"'
earliest_offset: $info_min_time$
latest_offset: $info_max_time$
- name: View risk events for the last 7 days for - "$dest$"
search: '| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$dest$") | stats count min(_time) as firstTime max(_time) as lastTime values(search_name) as "Search Name" values(risk_message) as "Risk Message" values(analyticstories) as "Analytic Stories" values(annotations._all) as "Annotations" values(annotations.mitre_attack.mitre_tactic) as "ATT&CK Tactics" by normalized_risk_object | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`'
earliest_offset: 7d
latest_offset: "0"
finding:
title: vbc.exe process [$process_name$] made a DNS query for $query$ from host $dest$.
entity:
field: dest
type: system
score: 50
threat_objects:
- field: process_name
type: process_name
analytic_story:
- Lokibot
asset_type: Endpoint
mitre_attack_id:
- T1071.004
product:
- Splunk Enterprise
- Splunk Enterprise Security
- Splunk Cloud
category: endpoint
security_domain: endpoint
tests:
- name: True Positive Test
attack_data:
- data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1071.004/vbc_dnsquery/vbc_dns_query.log
source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
sourcetype: XmlWinEventLog
test_type: unit
Stages and Predicates
Stage 1: search
`sysmon` EventCode=22 process_name="vbc.exe"
Stage 2: rename
| rename dvc as dest
Stage 3: stats
| stats count min(_time) as firstTime max(_time) as lastTime
BY answer answer_count dest
process_exec process_guid process_name
query query_count reply_code_id
signature signature_id src
user_id vendor_product QueryName
QueryResults QueryStatus
Stage 4: search
| `security_content_ctime(firstTime)`
Stage 5: search
| `security_content_ctime(lastTime)`
Stage 6: search
| `windows_visual_basic_commandline_compiler_dnsquery_filter`
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 |
|
process_name | eq |
|