Threat Intelligence Report — CVE-2026-73167

Executive Summary

CVE-2026-73167 is a CWE-78 OS Command Injection vulnerability in the web management interface of the Advantech EKI-1242IEIMS industrial Ethernet switch, affecting firmware version V1.06.01. A remote attacker who has obtained valid credentials can inject operating-system commands through crafted request parameters, executing them with root privileges on the underlying device. Because the EKI-1242IEIMS is an industrial network device typically deployed at the OT/IT boundary, successful exploitation grants an authenticated adversary full control of the switch and a potential pivot point into industrial control networks.

Technical Analysis

The vulnerability resides in the web management interface of the Advantech EKI-1242IEIMS, an industrial managed Ethernet switch. The weakness is classified CWE-78: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection'). According to the NVD description, the flaw is triggered by crafted request parameters submitted to the web management interface.

At the vulnerability-class level, OS command injection occurs when user-supplied input is concatenated into a command string that is subsequently passed to a shell interpreter (for example, via system(), popen(), or equivalent) without sanitization or with insufficient sanitization. Special shell metacharacters — such as ;, |, &&, $(...), or backticks — allow an attacker to terminate the intended command and append their own. The NVD description explicitly states that the result is arbitrary OS command execution as root, indicating the affected web process runs with elevated privileges or the injected commands are executed by a root-owned service.

Two characteristics of this CVE are operationally significant:

1. Authentication is required. The attacker must be remote authenticated before injection is possible. This means the vulnerability cannot be reached pre-authentication; the adversary needs valid web management credentials (default, weak, reused, or previously compromised).
2. Full root execution. Successful exploitation does not merely disclose data — it yields root-level command execution, giving the attacker complete control over the device operating system.

The NVD description does not identify specific vulnerable parameters, endpoint paths, function names, or the exact command being constructed. No public PoC, Nuclei template, or exploit code is available as of this report. Any claim about exact parameter names or endpoint paths would be speculation and is deliberately omitted.

Exploitation Scenarios

The following attack chain is inferred from the vulnerability class (CWE-78) and the details explicitly provided in the NVD description. No public PoC exists; all steps below describe the attack at the vulnerability-class level and do not assert unconfirmed implementation details.

1) Reconnaissance / target identification. An attacker scans internal or exposed networks for Advantech EKI-1242IEIMS web management interfaces. The device presents an HTTP/HTTPS management login page. Discovery can be performed with Shodan queries targeting Advantech product banners or web management titles, or through internal network scanning. The attacker identifies devices confirming firmware V1.06.01.

2) Credential acquisition / access. Because the flaw requires an authenticated attacker, the adversary must first obtain valid credentials. Common paths include default or weak factory credentials, reused passwords, credential stuffing, or credentials captured from prior compromise. Once logged in, the attacker has access to the web management interface parameters.

3) Injection trigger. The attacker submits a crafted request parameter to the web management interface containing shell metacharacters. Per the vulnerability class, the application fails to neutralize these special elements before passing the input to an OS command, allowing the attacker to break out of the intended command context and execute appended commands. The NVD description confirms this is achieved via crafted request parameters.

4) Execution and post-exploitation. The injected command runs as root. With root access, the attacker can read or modify device configuration, alter switch behavior (VLANs, routing, port configuration), install persistence, exfiltrate network topology data, or use the switch as a pivot into the broader OT network. Because industrial switches often sit at trust boundaries, this foothold can enable further lateral movement toward PLCs, HMIs, and SCADA systems.

Impact Assessment

The impact is severe. With root-level command execution, the confidentiality, integrity, and availability of the device and everything reachable through it are at risk. The inferred CVSS vector CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H reflects:

• AV:N (Network) — exploitable remotely over the network.
• AC:L (Low) — no special conditions beyond a valid crafted request.
• PR:L (Low / authenticated) — consistent with the requirement for a remote authenticated attacker.
• UI:N (None) — no user interaction needed once authenticated.
• C:H / I:H / A:H — root command execution compromises all three.

Note: NVD has not assigned an official CVSS score or vector for this CVE (score: N/A). The vector above is an analyst-derived estimate based on the stated conditions and should not be cited as an official NVD rating.

Blast radius: Any organization running Advantech EKI-1242IEIMS firmware V1.06.01 with the web management interface enabled. Industrial operators, utilities, manufacturing, transportation, and building-automation environments are the most likely affected sectors. Because the device is a network switch, compromise can affect all downstream traffic and devices.

Detection Guidance

Sigma Rule

title: Suspicious OS Command Injection Attempt Against Advantech EKI-1242IEIMS Web Interface
id: 8f3c1a2e-7b4d-4c9a-9e21-advantech-eki-cve-2026-73167
status: experimental
description: Detects shell metacharacters in HTTP request parameters targeting the Advantech EKI-1242IEIMS web management interface, indicative of CWE-78 command injection (CVE-2026-73167).
references:
  - https://nvd.nist.gov/vuln/detail/CVE-2026-73167
author: valtersit.com
date: 2026/01/01
logsource:
  category: webserver
  product: advantech
detection:
  selection_metachar:
    cs-uri-query|contains:
      - ';'
      - '|'
      - '&&'
      - '$('
      - '`'
      - '\n'
  selection_path:
    cs-uri-stem|contains:
      - '/cgi'
      - '/goform'
      - '/web'
      - 'EKI'
  filter_common:
    cs-uri-query|contains:
      - '&lang='
      - '&csrf='
  condition: selection_metachar and selection_path and not filter_common
falsepositives:
  - Legitimate administrative actions containing shell characters in comments or notes
level: high
tags:
  - attack.t1190
  - cve.2026-73167

Note: The cs-uri-stem values above are illustrative of typical embedded-web CGI patterns and are NOT confirmed endpoints for this CVE; tune them to the deployed device.

YARA Rule

rule CVE_2026_73167_Advantech_EKI_Command_Injection
{
    meta:
        description = "Detects indicators of OS command injection exploitation against Advantech EKI-1242IEIMS (CVE-2026-73167)"
        author = "valtersit.com"
        date = "2026-01-01"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2026-73167"
        cve = "CVE-2026-73167"

    strings:
        $s1 = "EKI-1242" ascii casewide
        $s2 = "Advantech" ascii casewide
        $s3 = "V1.06.01" ascii casewide
        $p1 = ";" ascii
        $p2 = "&&" ascii
        $p3 = "$(" ascii
        $p4 = "|" ascii

    condition:
        (any of ($s1, $s2)) and $s3 and 2 of ($p1, $p2, $p3, $p4)
}

Note: YARA is best suited here for scanning firmware images or logs for the affected version string combined with injection indicators; it cannot definitively confirm exploitation.

Suricata IDS Rule

alert http any any -> any any (msg:"CVE-2026-73167 Advantech EKI-1242IEIMS OS Command Injection Attempt"; flow:established,to_server; http.method; content:"GET"; http.uri; content:"EKI"; nocase; http.uri; pcre:"/(%3B|;|%7C|\||%26%26|&&|%24%28|\$\()/i"; reference:cve,2026-73167; reference:url,nvd.nist.gov/vuln/detail/CVE-2026-73167; classtype:web-application-attack; sid:202673167; rev:1;)

Elastic Detection

sequence by source.ip with maxspan=30s
  [network where event.action == "network_flow" and
     (http.request.method == "GET" or http.request.method == "POST") and
     (http.request.path : "*EKI*" or http.request.path : "*cgi*" or http.request.path : "*goform*") and
     http.request.body.text : ("*;*", "*|*", "*&&*", "*$(*")]

Note: Field mappings vary by Elastic integration (packetbeat/zeek/Elastic Agent HTTP logs). Adjust field names to your ingest pipeline. The glob list represents distinct match conditions; check your EQL version's support for multi-value : matching.

Splunk SPL Query

index=web OR index=network sourcetype=access_combined OR sourcetype=suricata
| eval uri=coalesce(uri, http_request_path, url)
| where match(uri, "(?i)(EKI|cgi|goform|web)") 
  AND match(uri, "(;|%3B|\||%7C|&&|%26%26|\$\(|%24%28|`)")
| table _time, src_ip, uri, status, user_agent
| sort - _time

Wazuh OSSEC Rule

<group name="web,advantech,cve-2026-73167,">
  <rule id="100731" level="12">
    <decoded_as>web-accesslog</decoded_as>
    <field name="url">\.*(EKI|cgi|goform).*</field>
    <regex type="pcre2">(?i)(;|%3B|\||%7C|&amp;&amp;|%26%26|\$\(|%24%28)</regex>
    <description>CVE-2026-73167: Possible OS command injection attempt against Advantech EKI-1242IEIMS web management interface</description>
    <mitre>
      <id>T1190</id>
    </mitre>
    <group>web_attack,</group>
  </rule>
</group>

Mitigation & Patch Guidance

Patch confidence: 0/4 — UNPATCHED. No vendor fix, firmware update, or advisory has been identified by any tracked source. Firmware V1.06.01 is confirmed affected; no patched version is known.

1) Immediate mitigations

• Disable or restrict the web management interface. If the EKI-1242IEIMS web UI is not operationally required, disable it. If it is required, restrict access via firewall/ACL to a dedicated management VLAN and trusted administrator hosts only.
• Do not expose the management interface to the internet. Confirm no WAN-facing access exists; audit NAT/port-forward rules.
• Rotate and harden credentials. Replace all default and weak passwords. Enforce unique, strong credentials for the web interface. This directly raises the bar because exploitation requires prior authentication.
• Monitor for anomalous commands. Use the detection rules above to alert on shell metacharacters in requests to the web interface.
• Network segmentation. Ensure OT devices sit behind strict segmentation so a compromised switch cannot readily reach other critical assets.

2) Patch / upgrade steps

• No patch currently exists. Monitor Advantech's official security advisories and Nozomi Networks Labs publications for a fix. When released, apply the firmware update immediately and re-verify the version string.
• As an interim compensating control, consider deploying a reverse proxy or WAF with strict parameter filtering in front of the management interface — though this does not remediate the underlying flaw.

3) Long-term hardening

• Maintain a firmware/vulnerability inventory for all OT network devices and subscribe to vendor and CERT advisories.
• Adopt a policy of network management interfaces accessible only via out-of-band or segmented management networks.
• Enforce MFA or certificate-based access where supported.
• Establish least-privilege administrative roles and continuous monitoring for post-exploitation behavior (unexpected config changes, new services, outbound connections from switches).

References

1. NVD — CVE-2026-73167: https://nvd.nist.gov/vuln/detail/CVE-2026-73167
2. MITRE CWE-78 — Improper Neutralization of Special Elements used in an OS Command: https://cwe.mitre.org/data/definitions/78.html
3. MITRE ATT&CK T1190 — Exploit Public-Facing Application: https://attack.mitre.org/techniques/T1190/
4. Nozomi Networks Labs — vulnerability research attributions (reporting source per NVD description): https://www.nozominetworks.com/labs
5. Advantech Security Advisories (monitor for patch): https://www.advantech.com/en/support/security

Threat actor / exploit-in-the-wild evidence: None. CISA KEV status is NO. No public PoC, exploit code, or Nuclei template is available. No known campaigns have been associated with CVE-2026-73167 as of this report.

Analyst note: Where the NVD description is sparse (no parameter names, endpoint paths, or function names disclosed), this report intentionally describes the attack at the vulnerability-class level rather than fabricating implementation details. CVSS score is officially N/A; any vector shown is an analyst estimate and is labeled as such.