Detection: PaperCut NG Remote Web Access Attempt

Updated Date: 2024-09-30 ID: 9fcb214a-dc42-4ce7-a650-f1d2cab16a6a Author: Michael Haag, Splunk Type: TTP Product: Splunk Enterprise Security

Description

The following analytic detects potential exploitation attempts on publicly accessible PaperCut NG servers. It identifies connections from public IP addresses to the server, specifically monitoring URI paths commonly used in proof-of-concept scripts for exploiting PaperCut NG vulnerabilities. This detection leverages web traffic data from the Web datamodel, focusing on specific URI paths and excluding internal IP ranges. This activity is significant as it may indicate an attempt to exploit known vulnerabilities in PaperCut NG, potentially leading to unauthorized access or control of the server. If confirmed malicious, attackers could gain administrative access, leading to data breaches or further network compromise.

1
2| tstats count from datamodel=Web where Web.url IN ("/app?service=page/SetupCompleted", "/app", "/app?service=page/PrinterList", "/app?service=direct/1/PrinterList/selectPrinter&sp=*", "/app?service=direct/1/PrinterDetails/printerOptionsTab.tab") NOT (src IN ("10.*.*.*","172.16.*.*", "192.168.*.*", "169.254.*.*", "127.*.*.*", "fc00::*", "fd00::*", "fe80::*")) by Web.http_user_agent Web.http_method, Web.url,Web.url_length Web.src, Web.dest Web.dest_port sourcetype 
3| `drop_dm_object_name("Web")` 
4| `security_content_ctime(firstTime)` 
5| `security_content_ctime(lastTime)` 
6| `papercut_ng_remote_web_access_attempt_filter`

Data Source

Name Platform Sourcetype Source
Suricata N/A 'suricata' 'suricata'

Macros Used

Name Value
security_content_ctime convert timeformat="%Y-%m-%dT%H:%M:%S" ctime($field$)
papercut_ng_remote_web_access_attempt_filter search *
papercut_ng_remote_web_access_attempt_filter is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Annotations

- MITRE ATT&CK
+ Kill Chain Phases
+ NIST
+ CIS
- Threat Actors
ID Technique Tactic
T1190 Exploit Public-Facing Application Initial Access
T1133 External Remote Services Initial Access
KillChainPhase.DELIVERY
KillChainPhase.INSTALLATION
NistCategory.DE_CM
Cis18Value.CIS_13
APT28
APT29
APT39
APT41
APT5
Agrius
Axiom
BackdoorDiplomacy
BlackTech
Blue Mockingbird
Cinnamon Tempest
Dragonfly
Earth Lusca
Ember Bear
FIN13
FIN7
Fox Kitten
GALLIUM
GOLD SOUTHFIELD
HAFNIUM
INC Ransom
Ke3chang
Kimsuky
Magic Hound
Moses Staff
MuddyWater
Play
Rocke
Sandworm Team
Threat Group-3390
ToddyCat
Volatile Cedar
Volt Typhoon
Winter Vivern
menuPass
APT18
APT28
APT29
APT41
Akira
Chimera
Dragonfly
Ember Bear
FIN13
FIN5
GALLIUM
GOLD SOUTHFIELD
Ke3chang
Kimsuky
LAPSUS$
Leviathan
OilRig
Play
Sandworm Team
Scattered Spider
TeamTNT
Threat Group-3390
Volt Typhoon
Wizard Spider

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 Notable Yes
Rule Title %name%
Rule Description %description%
Notable Event Fields user, dest
Creates Risk Event True
This configuration file applies to all detections of type TTP. These detections will use Risk Based Alerting and generate Notable Events.

Implementation

To successfully implement this search you need to be ingesting information on Web traffic that include fields relavent for traffic into the Web datamodel.

Known False Positives

False positives may be present, filter as needed.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message Risk Score Impact Confidence
URIs specific to PaperCut NG have been access by a public IP against $dest$. 63 90 70
The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.

References

Detection Testing

Test Type Status Dataset Source Sourcetype
Validation ✅ Passing N/A N/A N/A
Unit ✅ Passing Dataset suricata suricata
Integration ✅ Passing Dataset suricata suricata

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: 3