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feat: add OpenVPN parser and bruteforce detection #1762

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4d5c277
feat: add OpenVPN parser and bruteforce scenario
PrOOnOOb Apr 10, 2026
1a9d6f2
feat: add tests, docs, collection and fix parser for OpenVPN
PrOOnOOb Apr 10, 2026
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9 changes: 9 additions & 0 deletions .tests/openvpn-logs/config.yaml
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parsers:
- crowdsecurity/syslog-logs
- ./parsers/s01-parse/proonoob/openvpn.yaml
scenarios:
- ./scenarios/proonoob/openvpn-bf.yaml
postoverflows:
- ""
log_file: openvpn-logs.log
log_type: syslog
5 changes: 5 additions & 0 deletions .tests/openvpn-logs/openvpn-logs.log
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2026-04-10T12:00:01.000000+02:00 vpn ovpn-server[4892]: TLS Error: tls-crypt unwrapping failed from [AF_INET]1.2.3.4:11111
2026-04-10T12:00:02.000000+02:00 vpn ovpn-server[4892]: TLS Error: tls-crypt unwrapping failed from [AF_INET]1.2.3.4:22222
2026-04-10T12:00:03.000000+02:00 vpn ovpn-server[4892]: TLS Error: tls-crypt unwrapping failed from [AF_INET]1.2.3.4:33333
2026-04-10T12:00:04.000000+02:00 vpn ovpn-server[4892]: TLS Error: tls-crypt unwrapping failed from [AF_INET]5.6.7.8:44444
Apr 5 11:26:07 vpn ovpn-server[380]: TLS Error: tls-crypt unwrapping failed from [AF_INET]9.10.11.12:55555
128 changes: 128 additions & 0 deletions .tests/openvpn-logs/parser.assert
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len(results["s00-raw"]["crowdsecurity/syslog-logs"]) == 5
results["s00-raw"]["crowdsecurity/syslog-logs"][0].Success == true
results["s00-raw"]["crowdsecurity/syslog-logs"][0].Evt.Parsed["logsource"] == "syslog"
results["s00-raw"]["crowdsecurity/syslog-logs"][0].Evt.Parsed["message"] == "TLS Error: tls-crypt unwrapping failed from [AF_INET]1.2.3.4:11111"
results["s00-raw"]["crowdsecurity/syslog-logs"][0].Evt.Parsed["pid"] == "4892"
results["s00-raw"]["crowdsecurity/syslog-logs"][0].Evt.Parsed["program"] == "ovpn-server"
results["s00-raw"]["crowdsecurity/syslog-logs"][0].Evt.Parsed["timestamp8601"] == "2026-04-10T12:00:01.000000+02:00"
basename(results["s00-raw"]["crowdsecurity/syslog-logs"][0].Evt.Meta["datasource_path"]) == "openvpn-logs.log"
results["s00-raw"]["crowdsecurity/syslog-logs"][0].Evt.Meta["datasource_type"] == "file"
results["s00-raw"]["crowdsecurity/syslog-logs"][0].Evt.Meta["machine"] == "vpn"
results["s00-raw"]["crowdsecurity/syslog-logs"][0].Evt.Whitelisted == false
results["s00-raw"]["crowdsecurity/syslog-logs"][1].Success == true
results["s00-raw"]["crowdsecurity/syslog-logs"][1].Evt.Parsed["logsource"] == "syslog"
results["s00-raw"]["crowdsecurity/syslog-logs"][1].Evt.Parsed["message"] == "TLS Error: tls-crypt unwrapping failed from [AF_INET]1.2.3.4:22222"
results["s00-raw"]["crowdsecurity/syslog-logs"][1].Evt.Parsed["pid"] == "4892"
results["s00-raw"]["crowdsecurity/syslog-logs"][1].Evt.Parsed["program"] == "ovpn-server"
results["s00-raw"]["crowdsecurity/syslog-logs"][1].Evt.Parsed["timestamp8601"] == "2026-04-10T12:00:02.000000+02:00"
basename(results["s00-raw"]["crowdsecurity/syslog-logs"][1].Evt.Meta["datasource_path"]) == "openvpn-logs.log"
results["s00-raw"]["crowdsecurity/syslog-logs"][1].Evt.Meta["datasource_type"] == "file"
results["s00-raw"]["crowdsecurity/syslog-logs"][1].Evt.Meta["machine"] == "vpn"
results["s00-raw"]["crowdsecurity/syslog-logs"][1].Evt.Whitelisted == false
results["s00-raw"]["crowdsecurity/syslog-logs"][2].Success == true
results["s00-raw"]["crowdsecurity/syslog-logs"][2].Evt.Parsed["logsource"] == "syslog"
results["s00-raw"]["crowdsecurity/syslog-logs"][2].Evt.Parsed["message"] == "TLS Error: tls-crypt unwrapping failed from [AF_INET]1.2.3.4:33333"
results["s00-raw"]["crowdsecurity/syslog-logs"][2].Evt.Parsed["pid"] == "4892"
results["s00-raw"]["crowdsecurity/syslog-logs"][2].Evt.Parsed["program"] == "ovpn-server"
results["s00-raw"]["crowdsecurity/syslog-logs"][2].Evt.Parsed["timestamp8601"] == "2026-04-10T12:00:03.000000+02:00"
basename(results["s00-raw"]["crowdsecurity/syslog-logs"][2].Evt.Meta["datasource_path"]) == "openvpn-logs.log"
results["s00-raw"]["crowdsecurity/syslog-logs"][2].Evt.Meta["datasource_type"] == "file"
results["s00-raw"]["crowdsecurity/syslog-logs"][2].Evt.Meta["machine"] == "vpn"
results["s00-raw"]["crowdsecurity/syslog-logs"][2].Evt.Whitelisted == false
results["s00-raw"]["crowdsecurity/syslog-logs"][3].Success == true
results["s00-raw"]["crowdsecurity/syslog-logs"][3].Evt.Parsed["logsource"] == "syslog"
results["s00-raw"]["crowdsecurity/syslog-logs"][3].Evt.Parsed["message"] == "TLS Error: tls-crypt unwrapping failed from [AF_INET]5.6.7.8:44444"
results["s00-raw"]["crowdsecurity/syslog-logs"][3].Evt.Parsed["pid"] == "4892"
results["s00-raw"]["crowdsecurity/syslog-logs"][3].Evt.Parsed["program"] == "ovpn-server"
results["s00-raw"]["crowdsecurity/syslog-logs"][3].Evt.Parsed["timestamp8601"] == "2026-04-10T12:00:04.000000+02:00"
basename(results["s00-raw"]["crowdsecurity/syslog-logs"][3].Evt.Meta["datasource_path"]) == "openvpn-logs.log"
results["s00-raw"]["crowdsecurity/syslog-logs"][3].Evt.Meta["datasource_type"] == "file"
results["s00-raw"]["crowdsecurity/syslog-logs"][3].Evt.Meta["machine"] == "vpn"
results["s00-raw"]["crowdsecurity/syslog-logs"][3].Evt.Whitelisted == false
results["s00-raw"]["crowdsecurity/syslog-logs"][4].Success == true
results["s00-raw"]["crowdsecurity/syslog-logs"][4].Evt.Parsed["logsource"] == "syslog"
results["s00-raw"]["crowdsecurity/syslog-logs"][4].Evt.Parsed["message"] == "TLS Error: tls-crypt unwrapping failed from [AF_INET]9.10.11.12:55555"
results["s00-raw"]["crowdsecurity/syslog-logs"][4].Evt.Parsed["pid"] == "380"
results["s00-raw"]["crowdsecurity/syslog-logs"][4].Evt.Parsed["program"] == "ovpn-server"
results["s00-raw"]["crowdsecurity/syslog-logs"][4].Evt.Parsed["timestamp"] == "Apr 5 11:26:07"
basename(results["s00-raw"]["crowdsecurity/syslog-logs"][4].Evt.Meta["datasource_path"]) == "openvpn-logs.log"
results["s00-raw"]["crowdsecurity/syslog-logs"][4].Evt.Meta["datasource_type"] == "file"
results["s00-raw"]["crowdsecurity/syslog-logs"][4].Evt.Meta["machine"] == "vpn"
results["s00-raw"]["crowdsecurity/syslog-logs"][4].Evt.Whitelisted == false
len(results["s01-parse"]["proonoob/openvpn"]) == 5
results["s01-parse"]["proonoob/openvpn"][0].Success == true
results["s01-parse"]["proonoob/openvpn"][0].Evt.Parsed["logsource"] == "syslog"
results["s01-parse"]["proonoob/openvpn"][0].Evt.Parsed["message"] == "TLS Error: tls-crypt unwrapping failed from [AF_INET]1.2.3.4:11111"
results["s01-parse"]["proonoob/openvpn"][0].Evt.Parsed["pid"] == "4892"
results["s01-parse"]["proonoob/openvpn"][0].Evt.Parsed["program"] == "ovpn-server"
results["s01-parse"]["proonoob/openvpn"][0].Evt.Parsed["source_ip"] == "1.2.3.4"
results["s01-parse"]["proonoob/openvpn"][0].Evt.Parsed["sport"] == "11111"
results["s01-parse"]["proonoob/openvpn"][0].Evt.Parsed["timestamp8601"] == "2026-04-10T12:00:01.000000+02:00"
basename(results["s01-parse"]["proonoob/openvpn"][0].Evt.Meta["datasource_path"]) == "openvpn-logs.log"
results["s01-parse"]["proonoob/openvpn"][0].Evt.Meta["datasource_type"] == "file"
results["s01-parse"]["proonoob/openvpn"][0].Evt.Meta["log_type"] == "auth_failed"
results["s01-parse"]["proonoob/openvpn"][0].Evt.Meta["machine"] == "vpn"
results["s01-parse"]["proonoob/openvpn"][0].Evt.Meta["service"] == "openvpn"
results["s01-parse"]["proonoob/openvpn"][0].Evt.Meta["source_ip"] == "1.2.3.4"
results["s01-parse"]["proonoob/openvpn"][0].Evt.Whitelisted == false
results["s01-parse"]["proonoob/openvpn"][1].Success == true
results["s01-parse"]["proonoob/openvpn"][1].Evt.Parsed["logsource"] == "syslog"
results["s01-parse"]["proonoob/openvpn"][1].Evt.Parsed["message"] == "TLS Error: tls-crypt unwrapping failed from [AF_INET]1.2.3.4:22222"
results["s01-parse"]["proonoob/openvpn"][1].Evt.Parsed["pid"] == "4892"
results["s01-parse"]["proonoob/openvpn"][1].Evt.Parsed["program"] == "ovpn-server"
results["s01-parse"]["proonoob/openvpn"][1].Evt.Parsed["source_ip"] == "1.2.3.4"
results["s01-parse"]["proonoob/openvpn"][1].Evt.Parsed["sport"] == "22222"
results["s01-parse"]["proonoob/openvpn"][1].Evt.Parsed["timestamp8601"] == "2026-04-10T12:00:02.000000+02:00"
basename(results["s01-parse"]["proonoob/openvpn"][1].Evt.Meta["datasource_path"]) == "openvpn-logs.log"
results["s01-parse"]["proonoob/openvpn"][1].Evt.Meta["datasource_type"] == "file"
results["s01-parse"]["proonoob/openvpn"][1].Evt.Meta["log_type"] == "auth_failed"
results["s01-parse"]["proonoob/openvpn"][1].Evt.Meta["machine"] == "vpn"
results["s01-parse"]["proonoob/openvpn"][1].Evt.Meta["service"] == "openvpn"
results["s01-parse"]["proonoob/openvpn"][1].Evt.Meta["source_ip"] == "1.2.3.4"
results["s01-parse"]["proonoob/openvpn"][1].Evt.Whitelisted == false
results["s01-parse"]["proonoob/openvpn"][2].Success == true
results["s01-parse"]["proonoob/openvpn"][2].Evt.Parsed["logsource"] == "syslog"
results["s01-parse"]["proonoob/openvpn"][2].Evt.Parsed["message"] == "TLS Error: tls-crypt unwrapping failed from [AF_INET]1.2.3.4:33333"
results["s01-parse"]["proonoob/openvpn"][2].Evt.Parsed["pid"] == "4892"
results["s01-parse"]["proonoob/openvpn"][2].Evt.Parsed["program"] == "ovpn-server"
results["s01-parse"]["proonoob/openvpn"][2].Evt.Parsed["source_ip"] == "1.2.3.4"
results["s01-parse"]["proonoob/openvpn"][2].Evt.Parsed["sport"] == "33333"
results["s01-parse"]["proonoob/openvpn"][2].Evt.Parsed["timestamp8601"] == "2026-04-10T12:00:03.000000+02:00"
basename(results["s01-parse"]["proonoob/openvpn"][2].Evt.Meta["datasource_path"]) == "openvpn-logs.log"
results["s01-parse"]["proonoob/openvpn"][2].Evt.Meta["datasource_type"] == "file"
results["s01-parse"]["proonoob/openvpn"][2].Evt.Meta["log_type"] == "auth_failed"
results["s01-parse"]["proonoob/openvpn"][2].Evt.Meta["machine"] == "vpn"
results["s01-parse"]["proonoob/openvpn"][2].Evt.Meta["service"] == "openvpn"
results["s01-parse"]["proonoob/openvpn"][2].Evt.Meta["source_ip"] == "1.2.3.4"
results["s01-parse"]["proonoob/openvpn"][2].Evt.Whitelisted == false
results["s01-parse"]["proonoob/openvpn"][3].Success == true
results["s01-parse"]["proonoob/openvpn"][3].Evt.Parsed["logsource"] == "syslog"
results["s01-parse"]["proonoob/openvpn"][3].Evt.Parsed["message"] == "TLS Error: tls-crypt unwrapping failed from [AF_INET]5.6.7.8:44444"
results["s01-parse"]["proonoob/openvpn"][3].Evt.Parsed["pid"] == "4892"
results["s01-parse"]["proonoob/openvpn"][3].Evt.Parsed["program"] == "ovpn-server"
results["s01-parse"]["proonoob/openvpn"][3].Evt.Parsed["source_ip"] == "5.6.7.8"
results["s01-parse"]["proonoob/openvpn"][3].Evt.Parsed["sport"] == "44444"
results["s01-parse"]["proonoob/openvpn"][3].Evt.Parsed["timestamp8601"] == "2026-04-10T12:00:04.000000+02:00"
basename(results["s01-parse"]["proonoob/openvpn"][3].Evt.Meta["datasource_path"]) == "openvpn-logs.log"
results["s01-parse"]["proonoob/openvpn"][3].Evt.Meta["datasource_type"] == "file"
results["s01-parse"]["proonoob/openvpn"][3].Evt.Meta["log_type"] == "auth_failed"
results["s01-parse"]["proonoob/openvpn"][3].Evt.Meta["machine"] == "vpn"
results["s01-parse"]["proonoob/openvpn"][3].Evt.Meta["service"] == "openvpn"
results["s01-parse"]["proonoob/openvpn"][3].Evt.Meta["source_ip"] == "5.6.7.8"
results["s01-parse"]["proonoob/openvpn"][3].Evt.Whitelisted == false
results["s01-parse"]["proonoob/openvpn"][4].Success == true
results["s01-parse"]["proonoob/openvpn"][4].Evt.Parsed["logsource"] == "syslog"
results["s01-parse"]["proonoob/openvpn"][4].Evt.Parsed["message"] == "TLS Error: tls-crypt unwrapping failed from [AF_INET]9.10.11.12:55555"
results["s01-parse"]["proonoob/openvpn"][4].Evt.Parsed["pid"] == "380"
results["s01-parse"]["proonoob/openvpn"][4].Evt.Parsed["program"] == "ovpn-server"
results["s01-parse"]["proonoob/openvpn"][4].Evt.Parsed["source_ip"] == "9.10.11.12"
results["s01-parse"]["proonoob/openvpn"][4].Evt.Parsed["sport"] == "55555"
results["s01-parse"]["proonoob/openvpn"][4].Evt.Parsed["timestamp"] == "Apr 5 11:26:07"
basename(results["s01-parse"]["proonoob/openvpn"][4].Evt.Meta["datasource_path"]) == "openvpn-logs.log"
results["s01-parse"]["proonoob/openvpn"][4].Evt.Meta["datasource_type"] == "file"
results["s01-parse"]["proonoob/openvpn"][4].Evt.Meta["log_type"] == "auth_failed"
results["s01-parse"]["proonoob/openvpn"][4].Evt.Meta["machine"] == "vpn"
results["s01-parse"]["proonoob/openvpn"][4].Evt.Meta["service"] == "openvpn"
results["s01-parse"]["proonoob/openvpn"][4].Evt.Meta["source_ip"] == "9.10.11.12"
results["s01-parse"]["proonoob/openvpn"][4].Evt.Whitelisted == false
len(results["success"][""]) == 0
1 change: 1 addition & 0 deletions .tests/openvpn-logs/scenario.assert
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len(results) == 0
7 changes: 7 additions & 0 deletions collections/proonoob/openvpn.yaml
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name: proonoob/openvpn
description: "OpenVPN parser and bruteforce detection"
author: proonoob
parsers:
- proonoob/openvpn
scenarios:
- proonoob/openvpn-bf
22 changes: 22 additions & 0 deletions parsers/s01-parse/proonoob/openvpn.md
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## Overview

Parser for OpenVPN server logs. Supports both legacy syslog and modern ISO8601 timestamp formats.

## Configuration

Add to /etc/crowdsec/acquis.d/openvpn.yaml

## Detected Events

- auth_failed: TLS tls-crypt unwrapping failed (scanner/probe without valid key)
- auth_failed: AUTH_FAILED (failed authentication)
- auth_failed: TLS handshake failed
- auth_failed: Certificate VERIFY ERROR

## Log formats supported

Legacy syslog:
Apr 5 11:26:07 vpn ovpn-server[380]: TLS Error: tls-crypt unwrapping failed from [AF_INET]182.200.116.38:38382

Modern ISO8601:
2026-04-10T12:17:48.771346+02:00 vpn ovpn-server[448]: TLS Error: tls-crypt unwrapping failed from [AF_INET]182.200.116.38:38382
33 changes: 33 additions & 0 deletions parsers/s01-parse/proonoob/openvpn.yaml
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filter: "evt.Parsed.program == 'ovpn-server'"
onsuccess: next_stage
name: proonoob/openvpn
description: "Parse OpenVPN logs (supports both syslog and ISO8601 timestamp formats)"
pattern_syntax:
OPENVPN_TLS_CRYPT: "TLS Error: tls-crypt unwrapping failed from \\[AF_INET\\]%{IPV4:source_ip}:%{INT:sport}"
OPENVPN_AUTH_FAILED: "AUTH: Received control message: AUTH_FAILED.*\\[AF_INET\\]%{IPV4:source_ip}:%{INT:sport}"
OPENVPN_TLS_HANDSHAKE: "TLS Error: TLS handshake failed"
OPENVPN_VERIFY_ERROR: "VERIFY ERROR"
OPENVPN_CATCHALL: "%{GREEDYDATA}"
nodes:
- grok:
name: "OPENVPN_TLS_CRYPT"
apply_on: message
- grok:
name: "OPENVPN_AUTH_FAILED"
apply_on: message
- grok:
name: "OPENVPN_TLS_HANDSHAKE"
apply_on: message
- grok:
name: "OPENVPN_VERIFY_ERROR"
apply_on: message
- grok:
name: "OPENVPN_CATCHALL"
apply_on: message
statics:
- meta: service
value: openvpn
- meta: source_ip
expression: "evt.Parsed.source_ip"
- meta: log_type
value: auth_failed
14 changes: 14 additions & 0 deletions scenarios/proonoob/openvpn-bf.md
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## Overview

Detects IPs performing OpenVPN TLS bruteforce or probing attacks.
Bans IPs that trigger 3 or more TLS errors within 15 minutes.

## Configuration

Requires the proonoob/openvpn parser.

## Behavior

- Trigger: 3 TLS errors
- Time window: 15 minutes
- Remediation: ban
18 changes: 18 additions & 0 deletions scenarios/proonoob/openvpn-bf.yaml
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type: leaky
name: proonoob/openvpn-bf
description: "Detect OpenVPN probing and bruteforce attempts via TLS errors"
filter: "evt.Meta.service == 'openvpn' && evt.Meta.log_type == 'auth_failed'"
groupby: "evt.Meta.source_ip"
capacity: 2
leakspeed: "5m"
blackhole: "1m"
labels:
service: openvpn
type: bruteforce
remediation: true
confidence: 3
spoofable: 0
behavior: "openvpn:bruteforce"
label: "OpenVPN TLS bruteforce/probing"
classification:
- attack.T1110