ID | Technique | Tactic |
---|---|---|
T1190 | Exploit Public-Facing Application | Initial Access |
T1133 | External Remote Services | Initial Access |
Detection: PaperCut NG Suspicious Behavior Debug Log
EXPERIMENTAL DETECTION
This detection status is set to experimental. The Splunk Threat Research team has not yet fully tested, simulated, or built comprehensive datasets for this detection. As such, this analytic is not officially supported. If you have any questions or concerns, please reach out to us at research@splunk.com.
Description
The following analytic identifies potential exploitation attempts on a PaperCut NG server by analyzing its debug log data. It detects unauthorized or suspicious access attempts from public IP addresses and searches for specific URIs associated with known exploits. The detection leverages regex to parse unstructured log data, focusing on admin login activities. This activity is significant as it can indicate an active exploitation attempt on the server. If confirmed malicious, attackers could gain unauthorized access, potentially leading to data breaches or further compromise of the server.
Search
1`papercutng` (loginType=Admin OR userName=admin)
2| eval uri_match=if(match(_raw, "(?i)(\/app\?service=page\/SetupCompleted
3|\/app
4|\/app\?service=page\/PrinterList
5|\/app\?service=direct\/1\/PrinterList\/selectPrinter&sp=l1001
6|\/app\?service=direct\/1\/PrinterDetails\/printerOptionsTab\.tab)"), "URI matches", null())
7| eval ip_match=if(match(_raw, "(?i)((25[0-5]
8|2[0-4][0-9]
9|[01]?[0-9][0-9]?)\.(25[0-5]
10|2[0-4][0-9]
11|[01]?[0-9][0-9]?)\.(25[0-5]
12|2[0-4][0-9]
13|[01]?[0-9][0-9]?)\.(25[0-5]
14|2[0-4][0-9]
15|[01]?[0-9][0-9]?))") AND NOT match(_raw, "(?i)(10\.(25[0-5]
16|2[0-4][0-9]
17|[01]?[0-9][0-9]?)\.(25[0-5]
18|2[0-4][0-9]
19|[01]?[0-9][0-9]?)\.(25[0-5]
20|2[0-4][0-9]
21|[01]?[0-9][0-9]?))
22|(172\.(1[6-9]
23|2[0-9]
24|3[0-1])\.(25[0-5]
25|2[0-4][0-9]
26|[01]?[0-9][0-9]?)\.(25[0-5]
27|2[0-4][0-9]
28|[01]?[0-9][0-9]?))
29|(192\.168\.(25[0-5]
30|2[0-4][0-9]
31|[01]?[0-9][0-9]?)\.(25[0-5]
32|2[0-4][0-9]
33|[01]?[0-9][0-9]?))"), "IP matches", null())
34| where (isnotnull(uri_match) OR isnotnull(ip_match))
35| stats sparkline, count, values(uri_match) AS uri_match, values(ip_match) AS ip_match latest(_raw) BY host, index, sourcetype
36| `papercut_ng_suspicious_behavior_debug_log_filter`
Data Source
Name | Platform | Sourcetype | Source | Supported App |
---|---|---|---|---|
N/A | N/A | N/A | N/A | N/A |
Macros Used
Name | Value |
---|---|
papercutng | sourcetype="papercutng" |
papercut_ng_suspicious_behavior_debug_log_filter | search * |
papercut_ng_suspicious_behavior_debug_log_filter
is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.
Annotations
Default Configuration
This detection is configured by default in Splunk Enterprise Security to run with the following settings:
Setting | Value |
---|---|
Disabled | true |
Cron Schedule | 0 * * * * |
Earliest Time | -70m@m |
Latest Time | -10m@m |
Schedule Window | auto |
Creates Risk Event | False |
Implementation
Debug logs must be enabled and shipped to Splunk in order to properly identify behavior with this analytic.
Known False Positives
False positives may be present, as this is based on the admin user accessing the Papercut NG instance from a public IP address. Filter as needed.
Associated Analytic Story
Risk Based Analytics (RBA)
Risk Message | Risk Score | Impact | Confidence |
---|---|---|---|
Behavior related to exploitation of PaperCut NG has been identified on $host$. | 64 | 80 | 80 |
References
-
https://www.papercut.com/kb/Main/HowToCollectApplicationServerDebugLogs
-
https://github.com/inodee/threathunting-spl/blob/master/hunt-queries/HAFNIUM.md
-
https://www.horizon3.ai/papercut-cve-2023-27350-deep-dive-and-indicators-of-compromise/
-
https://www.huntress.com/blog/critical-vulnerabilities-in-papercut-print-management-software
Detection Testing
Test Type | Status | Dataset | Source | Sourcetype |
---|---|---|---|---|
Validation | Not Applicable | N/A | N/A | N/A |
Unit | ✅ Passing | Dataset | papercutng |
papercutng |
Integration | ✅ Passing | Dataset | papercutng |
papercutng |
Replay any dataset to Splunk Enterprise by using our replay.py
tool or the UI.
Alternatively you can replay a dataset into a Splunk Attack Range
Source: GitHub | Version: 2