THREAT INTELLIGENCE REPORT — CVE-2023-25914

Executive Summary

CVE-2023-25914 is an authenticated path traversal vulnerability in the Danfoss AK-SM800A, a Building Management System (BMS) / refrigeration monitoring controller widely deployed in commercial HVAC and cold-chain environments. An authenticated attacker can exploit improper input restriction in the device's XML interface to read arbitrary system files from the underlying server, potentially exposing configuration files, credentials, and secrets that enable full system compromise. With a CVSS score of 8.8, this vulnerability poses a critical risk to organizations operating Danfoss AK-SM800A devices, particularly critical infrastructure sites such as supermarkets, cold storage facilities, and data centers. The vendor has released version 3.3 as a mitigation, though official fix confirmation remains partial.

Technical Analysis

The CVE-2023-25914 vulnerability arises from improper restriction of path traversal in the Danfoss AK-SM800A's XML interface. The device exposes an XML-based interface that requires authentication to access. Due to the lack of proper input validation and path canonicalization, an authenticated user can manipulate the XML interface requests to traverse outside the intended filesystem scope and read arbitrary files.

Vulnerability Class: Path Traversal (CWE-22)

Attack Mechanism: The flaw belongs to the general class of path traversal attacks. When the XML interface handles file-related requests or parsing operations, it fails to properly sanitize user-supplied paths. An attacker who has obtained valid credentials can craft a request containing traversal sequences (e.g., ../) to escape restricted directories and access sensitive files outside the expected scope. Typically, path traversal of this nature can read files such as:

• /etc/passwd or equivalent operating system user databases
• /etc/shadow (if permission constraints allow)
• Application configuration files (web server configs, database connection strings)
• SSH keys, TLS certificates, and other secret material
• Source code or backup files

Technical Specifics: The NVD description does not disclose the exact URL endpoints, parameter names, or the precise file paths reachable. Insufficient technical detail is available regarding the specific XML element structure. What is known: the attack surface is the XML interface, authentication is required, and the impact is arbitrary file read from the underlying server.

Underlying Architecture: The AK-SM800A is an embedded controller running on a server-side operating system. The "XML interface" referenced suggests the device exposes a web service or API that handles XML-formatted requests/responses. This XML interface likely processes file I/O operations (e.g., import/export of configurations, retrieval of log files, or firmware-related functions) without performing proper path normalization.

The Impact Chain: File read leads to information disclosure. While file read alone may not execute code, the leaked data — credentials, internal network details, application secrets — can enable lateral movement, privilege escalation, or direct exploitation of other exposed services. The NVD description explicitly notes that "the information that can be read can lead to a full system compromise," indicating that the leaked data is sufficient for achieving administrative-level access.

Exploitation Scenarios

No public PoC or exploit code is available. The attack chain below is inferred from the vulnerability class (path traversal) and the NVD description.

Step 1: Reconnaissance and Target Identification

• Network scanning: Attackers scan for exposed Danfoss AK-SM800A devices on the internet using Shodan or similar tools. Default HTTP/HTTPS ports, vendor-specific banners, or XML service responses identify the device.
• Authentication acquisition: Since the vulnerability requires authentication, the attacker must obtain valid credentials. Common vectors include:
  • Default credentials left unchanged (Danfoss devices historically ship with default admin passwords).
  • Credential brute-forcing against the web/XML interface.
  • Credential stuffing using leaked credentials from previous breaches.
  • Physical access to facility operations documentation.

Step 2: Triggering the Flaw

• The attacker authenticates to the device's XML interface (web service).
• The attacker crafts an XML request that includes a file path parameter containing traversal sequences. Since the application fails to validate path normalization, the attacker can specify absolute paths or ../ sequences to escape the intended restricted directory.
• The XML parser/interface requests the file from the underlying operating system using the unsanitized path.

Step 3: Payload / Execution Method

The payload is a crafted XML request containing, at the vulnerability-class level, a path traversal pattern. For example (generic illustration, not a confirmed payload):

<?xml version="1.0"?>
<request>
  <action>retrieveFile</action>
  <file>../../../../etc/passwd</file>
</request>

The server processes this request, traverses the directory structure, and returns the contents of the target file in the XML response.

Step 4: Post-Exploitation Impact

• Credentials harvest: The attacker reads configuration files that contain db_user/db_password fields, API keys, or plaintext credentials for other systems.
• Operating system compromise: Reading /etc/shadow, /etc/passwd, or similar files enables offline password cracking to gain OS-level access.
• Lateral movement: Using harvested credentials, the attacker accesses other systems on the OT/IT network.
• Ransomware/Extortion: In critical infrastructure, attackers may deploy ransomware or sell access to the network.
• Full system takeover: The NVD description clearly states that the readable information can lead to full system compromise.

Note on Exploit Difficulty:

No public exploit is available. The vulnerability is authenticated, which raises the barrier. However, if default credentials are in use (common in OT/ICS deployments), the effective risk is near-trivial to exploit.

Impact Assessment

CVSS Score: 8.8 (High) — The high severity reflects:

• Attack Vector: Network (AV:N) — The device is exploitable remotely over the network.
• Attack Complexity: Low (AC:L) — No special conditions needed.
• Privileges Required: Low (PR:L) — Any authenticated user, possibly low-privileged, can exploit.
• User Interaction: None (UI:N) — No victim interaction required.

Impact Metrics: Confidentiality: High | Integrity: High | Availability: High — the NVD description explicitly states the flaw can lead to "full system compromise," indicating that file reads expand to system-level takeover, potentially crippling the BMS.

Business Impact:

• Sector: Commercial refrigeration, cold chain logistics, supermarkets, pharmaceutical storage, warehouses, and any facility using Danfoss BMS controllers.
• Operational impact: An exploited AK-SM800A controls critical HVAC/refrigeration; compromise could allow attackers to manipulate temperature setpoints, causing product spoilage, equipment damage, or unsafe environmental conditions.
• Regulatory impact: In healthcare/pharma (GDP, FDA 21 CFR Part 11) and food safety (HACCP), a security breach affecting temperature monitoring could trigger regulatory penalties and compliance failures.
• Reputational impact: Loss of trust for organizations managing critical cold-chain infrastructure.

Blast Radius:

• Direct: The AK-SM800A device and underlying server.
• Extended: The BMS network segment — many facilities interconnect BMS controllers with corporate IT networks. An attacker with the device can pivot to other BMS components, building management servers, and potentially the corporate network.
• Physical: Ability to disrupt refrigeration/HVAC systems could cause physical damage to stored goods or facility equipment.

Detection Guidance

Sigma Rule

title: Danfoss AK-SM800A Path Traversal via XML Interface
id: 3d8e9f6c-8b2a-4e5d-9f7c-1a2b3c4d5e6f
status: experimental
description: Detects path traversal attempts against Danfoss AK-SM800A XML interface through authenticated requests
author: Valters IT Security Team
date: 2024/01/15
tags:
  - attack.t1213
  - attack.t1005
  - cve.2023.25914
logsource:
  category: webserver
  product: generic
detection:
  selection_traversal:
    cs-method:
      - 'POST'
      - 'GET'
    cs-uri-query|contains:
      - '..%2f'
      - '..%5c'
      - '%2e%2e%2f'
      - '%2e%2e%5c'
      - '/../'
      - '\..\'
    cs-uri-stem|contains:
      - 'xml'
      - 'api'
      - 'interface'
  selection_sensitive_files:
    cs-uri-query|contains:
      - 'etc/passwd'
      - 'etc/shadow'
      - 'config'
      - 'password'
      - 'conf'
      - 'secret'
      - 'key'
      - 'credential'
  condition: selection_traversal and selection_sensitive_files
  timeframe: 15s
falsepositives:
  - Legitimate file retrieval functions that use absolute paths
  - Scanning tools performing benign path checks
level: high

YARA Rule

rule CVE_2023_25914_Danfoss_AK_SM800A_PathTraversal
{
    meta:
        author = "Valters IT Security Team"
        description = "Detects path traversal payloads targeting Danfoss AK-SM800A XML interface"
        cve = "CVE-2023-25914"
        date = "2024-01-15"
        version = "1.0"
        severity = "HIGH"
    strings:
        $xml_header = "<?xml" ascii nocase
        $traversal1 = "../" ascii nocase
        $traversal2 = "..\\" ascii nocase
        $traversal3 = "%2e%2e%2f" ascii nocase
        $traversal4 = "%2e%2e%5c" ascii nocase
        $absolute_path1 = "/etc/passwd" ascii nocase
        $absolute_path2 = "/etc/shadow" ascii nocase
        $absolute_path3 = "/etc/ssh" ascii nocase
        $absolute_path4 = "C:\\Windows\\System32\\config" ascii nocase
        $cfg_file = ".conf" ascii nocase
        $key_file = "id_rsa" ascii nocase
        $config_ref = "config" ascii nocase
    condition:
        uint16(0) == 0x3C3F and  // "<?" - XML start
        (
            any of ($traversal*) or
            any of ($absolute_path*) or
            ($config_ref and any of ($absolute_path*))
        ) and
        (
            $xml_header and
            (any of ($traversal*) or any of ($absolute_path*))
        )
}

Suricata IDS Rule

alert http any any -> $DANFOSS_DEVICES any (msg:"CVE-2023-25914 Danfoss AK-SM800A XML Path Traversal Attempt"; flow:established,to_server; content:"POST"; http_method; content:"xml"; http_uri; nocase; pcre:"/(%2e%2e%2f|%2e%2e%5c|\.\.\/|\.\.\\)/i"; pcre:"/(etc/passwd|etc/shadow|\.ssh|\.conf|\.pem|\.key)/i"; classtype:attempted-admin; sid:130025914; rev:1; reference:cve,2023-25914; priority:1;)

alert http any any -> $DANFOSS_DEVICES any (msg:"CVE-2023-25914 Danfoss AK-SM800A Potential File Disclosure via XML Interface"; flow:established,to_server; content:"XML"; http_header; noche; content:"retrieveFile"; http_client_body; nocase; pcre:"/(\.\.\/|\.\.\\\\)+[a-zA-Z0-9_\/\\\\]+/i"; classtype:attempted-information-leak; sid:130025915; rev:1; reference:cve,2023-25914; priority:2;)

Elastic Detection

// Elastic EQL rule for CVE-2023-25914
sequence by host.name, user.name with maxspan=5s
  [network where
     destination.port in (80, 443, 8080, 8443) and
     network.protocol == "http" and
     http.request.method == "POST" and
     url.path contains ("/xml", "/api", "/interface") and
     // Look for traversal patterns (URL-encoded or raw)
     url.query contains ("..%2f", "..%5c", "%2e%2e%2f", "%2e%2e%5c", "/../", "\\..\\")
  ]
  [file where
     file.path regex~ """/.*(etc/passwd|etc/shadow|\.ssh/|\.conf|\.pem|\.key|\.sqlite).*""" and
     process.name == "httpd" or
     process.name == "java" or
     process.name == "node" or
     process.name == "python"
  ]

Splunk SPL Query

index=web OR index=proxy 
  sourcetype=*http*
  (uri_path="*/*xml*" OR uri_path="*/xml*" OR uri_path="*api*" OR uri_path="*interface*")
  AND (
    uri_query="*..%2f*" OR 
    uri_query="*..%5c*" OR 
    uri_query="*%2e%2e%2f*" OR 
    uri_query="*%2e%2e%5c*" OR 
    uri_query="*/../*" OR 
    uri_query="*\\..\\*" OR 
    uri_path="*/../*"
  )
  AND (
    uri_query="*etc/passwd*" OR
    uri_query="*etc/shadow*" OR
    uri_query="*.conf*" OR
    uri_query="*.pem*" OR
    uri_query="*.key*" OR
    uri_query="*password*" OR
    uri_query="*credential*"
  )
  OR 
  index=network 
  sourcetype=*syslog*
  (src_ip != "10.0.0.0/8" AND src_ip != "172.16.0.0/12" AND src_ip != "192.168.0.0/16")
  AND dest_port IN (80,443,8080,8443)
  AND payload="*..%2f*etc*passwd*"
| stats count, values(uri_query) as traversal_patterns, values(src_ip) as attack_sources, values(dest_ip) as target_devices by _time, dest_ip
| where count > 2
| sort - _time

Wazuh OSSEC Rule

<group name="web,path_traversal,">

  <rule id="100091" level="14">
    <decoded_as>web</decoded_as>
    <match>POST</match>
    <regex>(\%2e\%2e\%2f|\%2e\%2e\%5c|\.\./|\.\.\\)</regex>
    <regex>(etc/passwd|etc/shadow|\.ssh|\.conf|\.pem|\.key|\.sqlite)</regex>
    <description>CVE-2023-25914 - Danfoss AK-SM800A path traversal attempt detected via XML interface</description>
    <group>attack.attempt,attck.t1213,cve202325914,</group>
    <mitre>
      <id>T1213</id>
      <id>T1005</id>
    </mitre>
    <info type="cve">CVE-2023-25914</info>
    <info type="link">https://nvd.nist.gov/vuln/detail/CVE-2023-25914</info>
    <options>no_full_log</options>
    <var name="srcip">any</var>
    <var name="dstip">any</var>
  </rule>

  <rule id="100092" level="10">
    <if_sid>100091</if_sid>
    <frequency>5</frequency>
    <timeframe>60</timeframe>
    <description>CVE-2023-25914 - Multiple path traversal attempts to Danfoss AK-SM800A from the same source IP</description>
    <group>attack.recon,attck.t1213,cve202325914,</group>
  </rule>

  <rule id="100093" level="15">
    <if_sid>100091</if_sid>
    <regex>response_error|401|403</regex>
    <description>CVE-2023-25914 - Path traversal attempt received error response, may indicate privilege escalation attempt</description>
    <group>attack.attempt,attck.t1213,cve202325914,</group>
    <info type="cve">CVE-2023-25914</info>
  </rule>

</group>

Mitigation & Patch Guidance

Patch Confidence: 1/4 (PARTIAL) — Only a workaround/mitigation is provided; no official confirmed fix. Effort required: high (upgrade to version 3.3 required, custom controls).

1) Immediate Mitigations (apply within 24–48 hours)

• Upgrade to Danfoss AK-SM800A version 3.3 — the only vendor-provided mitigation. Confirm the version resolves path traversal via vendor documentation.
• Restrict network access: Place AK-SM800A on an isolated OT/ICS VLAN. Block inbound access from the internet at the perimeter firewall. If remote access is required, use a VPN with MFA, not direct exposure.
• Enforce strong authentication: Disable default credentials. Require unique, strong passwords for all accounts. Implement account lockout policies to prevent brute-forcing.
• Deploy WAF/IPS rules: Use the Suricata/Wazuh rules provided above in your network monitoring stack to actively block or flag path traversal patterns.
• Enable audit logging: Ensure the device and surrounding infrastructure log all administrative and XML interface actions to a SIEM for retrospective detection.

2) Patch/Upgrade Steps

1. Backup: Export current device configuration and save to a secure location.
2. Download version 3.3 from the official Danfoss support portal (validate checksum).
3. Schedule maintenance window — device reboot is expected. Notify facility operations staff.
4. Apply update via the device's approved update mechanism.
5. Verify the post-update version and re-test the XML interface with legitimate operations.
6. Change all passwords post-update as a precautionary measure.
7. Monitor for any anomalous behavior for 30 days post-upgrade.

Note: If version 3.3 cannot be applied immediately, segment the device from the corporate network entirely and restrict to local management only.

3) Long-Term Hardening

• Inventory management: Catalogue all Danfoss AK-SM800A deployments (and other BMS devices). Maintain a hardware/software asset register.
• Network architecture: Implement Zero Trust in OT environments. Micro-segment BMS devices from corporate IT. Restrict egress as well as ingress.
• Credential hygiene: Rotate all device credentials quarterly. Disable unused accounts.
• Patch management program: Subscribe to Danfoss security advisories. Apply vendor updates within 30 days for critical infrastructure.
• Continuous monitoring: Deploy the detection rules above permanently in your SIEM/IDS infrastructure.
• Incident response readiness: Add BMS/OT device compromise to your incident response playbook. Practice runbooks for facility control system incidents.

References

1. NVD Entry: https://nvd.nist.gov/vuln/detail/CVE-2023-25914 — Official CVE description, CVSS scoring, and references.
2. Danfoss Product Page: https://www.danfoss.com/en/products/ak-sm800a — Official product documentation and firmware downloads (version 3.3 update).
3. AT&T AlienVault OTD / VulnDB References: Various vulnerability-tracking platforms (search CVE-2023-25914) — includes timeline and third-party analysis.
4. CISA ICS-CERT Advisories: https://www.cisa.gov/resources-tools/resources/ics-recommended-practices — For guidance on securing ICS/SCADA devices in critical infrastructure.
5. First.org CVSS Calculator: https://www.first.org/cvss/calculator/3.1 — For verifying CVSS vector and understanding score composition.

Known Threat Actor Campaigns: No active, publicly documented campaigns exploiting CVE-2023-25914 have been identified as of the analysis date. The EPSS score of 0.00674 (48.7th percentile) indicates low overall exploitation probability in the wild, but the threat landscape for BMS/OT devices is evolving, and newly disclosed OT vulnerabilities often become targets within 6–12 months. Organizations should treat this as a high-priority patching item regardless of current exploit prevalence.