Adversaries may leverage weaknesses to exploit internet-facing software for initial access into an industrial network. Internet-facing software may be user applications, underlying networking implementations, an assets operating system, weak defenses, etc. Targets of this technique may be intentionally exposed for the purpose of remote management and visibility.
An adversary may seek to target public-facing applications as they may provide direct access into an ICS environment or the ability to move into the ICS network. Publicly exposed applications may be found through online tools that scan the internet for open ports and services. Version numbers for the exposed application may provide adversaries an ability to target specific known vulnerabilities. Exposed control protocol or remote access ports found in Commonly Used Port may be of interest by adversaries.
| ID | Name | Description |
|---|---|---|
| G0034 | Sandworm Team |
Sandworm Team actors exploited vulnerabilities in GE's Cimplicity HMI and Advantech/Broadwin WebAccess HMI software which had been directly exposed to the internet. [1] [2] |
| ID | Asset |
|---|---|
| A0008 | Application Server |
| A0016 | Firewall |
| A0011 | Virtual Private Network (VPN) Server |
| A0001 | Workstation |
| ID | Mitigation | Description |
|---|---|---|
| M0948 | Application Isolation and Sandboxing |
Application isolation will limit the other processes and system features an exploited target can access. Examples of built in features are software restriction policies, AppLocker for Windows, and SELinux or AppArmor for Linux. |
| M0950 | Exploit Protection |
Web Application Firewalls may be used to limit exposure of applications to prevent exploit traffic from reaching the application. [3] |
| M0930 | Network Segmentation |
Segment externally facing servers and services from the rest of the network with a DMZ or on separate hosting infrastructure. |
| M0926 | Privileged Account Management | |
| M0951 | Update Software |
Regularly scan externally facing systems for vulnerabilities and establish procedures to rapidly patch systems when critical vulnerabilities are discovered through scanning and public disclosure. |
| M0916 | Vulnerability Scanning |
Regularly scan externally facing systems for vulnerabilities and establish procedures to rapidly patch systems when critical vulnerabilities are discovered through scanning and public disclosure. |
| ID | Name | Analytic ID | Analytic Description |
|---|---|---|---|
| DET0740 | Detection of Exploit Public-Facing Application | AN1873 |
Real-time monitoring identifies an internet-facing Industrial Control System (ICS) application server, web Human-Machine Interface (HMI), historian web interface, vendor remote access portal) process spawning an unexpected child process immediately following an inbound web request containing exploit-pattern content. Documented across multiple incidents involving internet-exposed ICS web interfaces. OT operational-fidelity gate: Alert only when execution violates an approved signer/hash/path/parent/process or tool allowlist, or originates from an unauthorized user/tool, and is tied to an OT asset or follow-on OT-relevant action. Suppress vendor-signed software, approved engineering utilities, diagnostics, patching, backup, and documented maintenance. Analyst implementation must limit predicates to fields actually retained by the web server/WAF (for example URI/path/query/header/status/source); request-body or payload signatures require WAF/DPI or request-body logging and must not be inferred from a basic access log. |
| AN2133 |
Real-time monitoring identifies web server or Industrial Control System (ICS) application logs showing exploit-pattern requests to Industrial Control System (ICS) vendor web interfaces, followed by the web server daemon User Identifier (UID) spawning unexpected shell processes. OT operational-fidelity gate: Alert only when execution violates an approved signer/hash/path/parent/process or tool allowlist, or originates from an unauthorized user/tool, and is tied to an OT asset or follow-on OT-relevant action. Suppress vendor-signed software, approved engineering utilities, diagnostics, patching, backup, and documented maintenance. Analyst implementation must limit predicates to fields actually retained by the web server/WAF (for example URI/path/query/header/status/source); request-body or payload signatures require WAF/DPI or request-body logging and must not be inferred from a basic access log. |
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| AN2173 |
Real-time monitoring identifies exploit-pattern HTTP/HTTPS traffic targeting an ICS DMZ application from a source or request pattern outside the approved application baseline. OT operational-fidelity gate: Alert only when execution violates an approved signer/hash/path/parent/process or tool allowlist, or originates from an unauthorized user/tool, and is tied to an OT asset or follow-on OT-relevant action. Suppress vendor-signed software, approved engineering utilities, diagnostics, patching, backup, and documented maintenance. |
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| AN2235 |
Real-time monitoring identifies Hypertext Transfer Protocol (HTTP) requests to an embedded device's management web interface containing exploit-pattern content (oversized parameters, directory traversal sequences) from a source not in the approved engineering workstation list. OT operational-fidelity gate: Alert only when execution violates an approved signer/hash/path/parent/process or tool allowlist, or originates from an unauthorized user/tool, and is tied to an OT asset or follow-on OT-relevant action. Suppress vendor-signed software, approved engineering utilities, diagnostics, patching, backup, and documented maintenance. |