Threat Intelligence Report — CVE-2023-25911

Authenticated OS Command Injection in Danfoss AK-EM100

Executive Summary

CVE-2023-25911 is an authenticated OS command injection vulnerability in the web application of the Danfoss AK-EM100, an energy monitoring device used in industrial and commercial refrigeration systems. An authenticated user with access to the web interface can execute arbitrary operating system commands on the underlying device hardware through crafted web application parameters.

The vulnerability carries a CVSS score of 9.9, reflecting near-maximal severity due to the combination of network exploitability, low authentication barrier, and the potential for complete compromise of the affected device. Because the AK-EM100 has been declared End of Life (EOL) with no official patch available, affected organizations must treat this as a permanent exposure and implement compensating controls or plan device replacement.

Technical Analysis

The Danfoss AK-EM100 is an energy management controller commonly deployed in supermarket refrigeration systems, cold storage facilities, and other commercial refrigeration environments. It provides a web-based interface for configuration, monitoring, and data retrieval.

Vulnerability Mechanism: The NVD description states that "the Danfoss AK-EM100 web applications allow for an authenticated user to perform OS command injection through the web application parameters." This indicates that user-supplied input submitted through web application parameters is not properly sanitized or validated before being used in operating system command construction. An attacker who has authenticated access to the web interface can inject additional OS commands by manipulating parameter values.

Attack Surface: The vulnerability is reachable over the network via the web application. The authentication requirement (CVSS vector includes PR:L — low privileges) means that a valid account with even minimal permissions is sufficient to trigger the vulnerability. The AK-EM100 is typically deployed on industrial control networks, sometimes with remote access for monitoring and maintenance, which expands the practical attack surface beyond the local facility.

Code-Level Analysis: Insufficient technical detail is available in the public description to identify specific functions, endpoints, or parameter names. The vulnerability class is OS command injection (CWE-78), which typically occurs when application code concatenates user input directly into shell command strings without proper escaping or validation. Common injection points include device configuration fields, network settings, firmware update parameters, and diagnostic tool inputs.

The CVSS score of 9.9 with a scope change (S:C) indicator suggests that the impact extends beyond the vulnerable component itself — successful exploitation may allow an attacker to pivot to adjacent network segments or compromise additional devices from the AK-EM100 as a foothold.

Exploitation Scenarios

Note: No public PoC or exploit code is available for this CVE. The following attack chain is inferred from the vulnerability class (OS command injection) and the general characteristics of the AK-EM100's deployment environment.

Step 1 — Reconnaissance and Target Identification: An attacker identifies AK-EM100 devices through network scanning (Shodan dorks such as "AK-EM100" or "Danfoss AK-EM") or through passive network monitoring of industrial control protocols. The device's web interface on port 80/443 serves as the primary attack surface. The attacker also identifies valid credentials — these may be obtained through credential stuffing attacks using default factory credentials, brute-force attacks on weak passwords, or harvesting from phishing campaigns targeting facility maintenance staff.

Step 2 — Authentication and Flaw Triggering: The attacker authenticates to the web interface using acquired or guessed credentials. Once logged in, they navigate to web application functions that accept user input and pass it to system commands. The attacker submits crafted input through web application parameters that include command injection payloads such as command separators (;, &&, |) followed by arbitrary OS commands. Typical injection vectors include fields for device naming, network configuration, or diagnostic commands.

Step 3 — Payload Execution: Upon submitting the crafted parameter, the application constructs an OS command string that includes the attacker's injected payload. The operating system executes the full command chain, including the attacker's injected commands. The injected commands run with the privileges of the web application service account — potentially root or administrator, depending on device configuration.

Step 4 — Post-Exploitation Impact: On a successful injection, the attacker achieves full remote code execution on the AK-EM100 device. Potential post-exploitation activities include: (1) extracting configuration data, credentials, and network topology information from the device; (2) modifying device settings to disrupt refrigeration monitoring or energy optimization; (3) using the device as a pivot point to reach other systems on the industrial control network; (4) installing persistent backdoors or cryptocurrency miners; (5) disabling monitoring capabilities to conceal the intrusion. Since the device is EOL, the attacker's foothold is effectively permanent.

Impact Assessment

Business Impact: The Danfoss AK-EM100 is deployed in commercial and industrial refrigeration environments. Compromise of these devices can lead to operational disruption of refrigeration monitoring and energy management functions, with potential downstream effects on cold chain integrity and food safety compliance. The device functions as an energy management controller, meaning tampering could result in increased energy consumption, suboptimal refrigeration performance, and — in extreme cases — spoilage of temperature-sensitive inventory.

CVSS Analysis: The CVSS score of 9.9 reflects:

• Network exploitability (AV:N) — the vulnerability is reachable remotely
• Low authentication barrier (PR:L) — any authenticated user can trigger it
• No user interaction required (UI:N)
• Scope change (S:C) — impact extends beyond the vulnerable component
• Complete confidentiality, integrity, and availability impact (C:H/I:H/A:H)

Blast Radius: At minimum, the affected AK-EM100 device is fully compromised. Given the industrial deployment context and scope change indicator, the blast radius may include the broader refrigeration control network, building management systems, and potentially enterprise IT networks if the OT/IT boundary is poorly segmented.

Exposure Status: No evidence of exploitation in the wild has been reported, and the CISA KEV (Known Exploited Vulnerabilities) catalog does not list this CVE. The EPSS score of 0.02302 (81.7th percentile) indicates a moderate probability of exploitation in the near future when compared to other published CVEs. Attackers will likely develop exploit code as information about this vulnerability class becomes more widely disseminated.

Detection Guidance

The following detection rules are provided to help identify potential exploitation attempts of CVE-2023-25911.

Sigma Rule

title: Danfoss AK-EM100 OS Command Injection Attempt
id: 4b7d2c0a-8f3e-4b71-9a2c-1d9e7a5b6c4f
status: experimental
description: Detects potential OS command injection attempts against Danfoss AK-EM100 web application parameters
logsource:
  category: webserver
  product: apache
detection:
  selection:
    c-uri|contains:
      - ';'
      - '&&'
      - '|'
      - '`'
      - '$('
  filter:
    c-uri|contains:
      - 'cmd='
      - 'command='
  condition: selection and filter
falsepositives:
  - Legitimate use of special characters in URL parameters
level: high
tags:
  - attack.t1059
  - attack.execution
  - cve.2023-25911

YARA Rule

rule Danfoss_AK_EM100_Command_Injection
{
    meta:
        author = "Valters IT Security Research"
        description = "Detects command injection strings targeting Danfoss AK-EM100 web interfaces"
        date = "2024-01-15"
        cve = "CVE-2023-25911"
        severity = "high"
    strings:
        $inject_delim1 = ";"
        $inject_delim2 = "&&"
        $inject_delim3 = "|"
        $inject_subshell = "$("
        $akem100 = "AK-EM100" ascii wide
        $danfoss = "Danfoss" ascii wide
        $cmd_target = "ping" ascii wide
        $cmd_target2 = "cat" ascii wide
        $cmd_target3 = "wget" ascii wide
        $cmd_target4 = "curl" ascii wide
    condition:
        any of ($inject_*) and any of ($cmd_target*) and (any of ($akem100, $danfoss) or filesize < 10MB)
}

Suricata IDS Rule

alert http any any -> any any (msg:"CVE-2023-25911 Danfoss AK-EM100 OS Command Injection Attempt"; flow:established,to_server; content:"GET"; http_method; content:"AK-EM100"; http_uri; nocase; content:";"; http_uri; distance:0; content:"&&"; http_uri; distance:0; content:"|"; http_uri; distance:0; content:"`"; http_uri; distance:0; content:"$("; http_uri; distance:0; classtype:attempted-admin; reference:cve,2023-25911; sid:10025911; rev:1;)

Elastic Detection

sequence by source.ip with maxspan=30s
  [network where destination.port == 80 and
   network.protocol == "http" and
   http.request.body.text contains "AK-EM100"]
  [process where event.type == "start" and
   (process.command_line contains ";" or
    process.command_line contains "&&" or
    process.command_line contains "|" or
    process.command_line contains "`")]

Splunk SPL Query

index=web sourcetype=access_combined dest_port=80
| where like(uri_path, "%AK-EM100%")
| regex uri_query="(;|&&|\||`|\$\().+"
| stats count by src_ip, dest_ip, uri_path, uri_query, _time
| sort -count

Wazuh OSSEC Rule

<group name="danfoss_akem100,">
  <rule id="100259" level="12">
    <decoded_as>web</decoded_as>
    <match>AK-EM100</match>
    <regex>(\;|\&\&|\||\`|\$\().*</regex>
    <description>Danfoss AK-EM100 - possible OS command injection attempt (CVE-2023-25911)</description>
    <mitre>
      <id>T1059</id>
    </mitre>
    <group>attack_execution,</group>
    <info type="cve">CVE-2023-25911</info>
  </rule>
</group>

Mitigation & Patch Guidance

Patch Confidence: 1/4 — PARTIAL

No official patch is available for CVE-2023-25911. The Danfoss AK-EM100 has been declared End of Life (EOL), and Danfoss advises phasing out this type of device. The following mitigation steps are recommended:

Immediate Mitigations:

1. Network segmentation: Isolate AK-EM100 devices from the general corporate network. Place them on a dedicated OT/ICS network segment with strict firewall rules limiting access to authorized maintenance personnel only.
2. Access restriction: Restrict access to the AK-EM100 web interface to a minimal set of IP addresses (allowlist). Disable remote access unless absolutely required for business operations.
3. Credential hardening: Immediately change all default factory credentials. Enforce strong, unique passwords for all user accounts on the device. Implement multi-factor authentication if supported via a front-end proxy.
4. Monitoring: Deploy detection rules (see Detection Guidance) to monitor for command injection attempts and anomalous web requests targeting AK-EM100 devices.
5. Disable unused services: If the device supports disabling unused web services or features, do so to reduce the attack surface.

Patch/Upgrade Steps:

1. No official patch exists. Do not wait for one — the product is EOL.
2. Plan device replacement: Work with Danfoss or a systems integrator to identify a modern replacement for the AK-EM100. Prioritize replacement for devices that are externally accessible or have confirmed weak credentials.
3. If decommissioning is not immediate: Place the device behind a reverse proxy that performs strict input validation and filtering of request parameters before forwarding to the AK-EM100.

Long-Term Hardening:

1. Asset lifecycle management: Implement a policy requiring that EOL devices be replaced within a defined timeline, especially when they contain known exploitable vulnerabilities.
2. OT network security: Implement a full OT security program including network segmentation, immutable backups, and regular vulnerability scanning of all ICS devices.
3. Vendor accountability: Before procuring new industrial control devices, require vendors to provide a security support lifecycle commitment and verified patching process.
4. Compensating controls: If replacement is not feasible, place the device behind a WAF or dedicated command-injection-prevention gateway that filters malicious payloads.

References

1. NVD Entry: NVD — CVE-2023-25911 — https://nvd.nist.gov/vuln/detail/CVE-2023-25911
2. CISA Known Exploited Vulnerabilities Catalog: https://www.cisa.gov/known-exploited-vulnerabilities-catalog — CVE-2023-25911 is NOT listed (as of this report)
3. Danfoss Product Information: https://www.danfoss.com — AK-EM100 product page (EOL notification)
4. First.org EPSS: https://www.first.org/epss — EPSS score 0.02302 (81.7th percentile)
5. MITRE ATT&CK: https://attack.mitre.org — Technique T1059 (OS Command Execution) and T0859 (Unsafe OS Command, ICS)

Threat Actor Campaigns: As of this report, no known threat actor campaigns, exploit-in-the-wild evidence, or publicly available PoC exploits have been identified for CVE-2023-25911. The vulnerability remains a latent risk — organizations should treat it as a high-priority item for remediation despite the lack of observed exploitation, given the device's extensive deployment in critical refrigeration infrastructure and its EOL status.