CVE-2023-25913

Executive Summary

CVE-2023-25913 is an authentication bypass vulnerability affecting the Danfoss AK-SM800A supervisory controller, a building automation and refrigeration monitoring device. The flaw enables an unauthenticated or improperly authenticated attacker to generate web reports that disclose sensitive operational information — including internal IP addresses, usernames, store names, and other confidential data. With a CVSS base score of 7.5 (High severity), the vulnerability exposes enterprise facility-management environments to information disclosure and reconnaissance, which can be chained with other attacks on OT/ICS infrastructure. Danfoss has claimed a fix in version 3.3, though this is based on a single source and is not independently confirmed; affected version ranges are not enumerated in the public data.

Technical Analysis

The NVD description identifies the root cause as an authentication flaw in the Danfoss AK-SM800A. The vulnerability class is an authentication bypass that permits an attacker to invoke web report generation functionality without proper authorization. While the description does not specify whether the bypass stems from faulty session management, a weak access-control check, or mishandling of authentication tokens, the observable outcome is a generation of web reports exposing sensitive data.

The AK-SM800A is an embedded supervisory controller used in commercial refrigeration systems — typically deployed at grocery stores, cold-chain facilities, and similar retail environments. It exposes a web-based management interface for monitoring and configuration. The vulnerable report-generation feature likely accesses backend data stores (controller configuration, network settings, user accounts) and renders them as web pages. Because the authentication flaw bypasses the authorization gate, any request — regardless of authentication state — can trigger report generation.

Attack surface details from the description are minimal. We know the flaw is present in the web-report feature. We do not have access to specific endpoints, function names, or parameters. The mechanism can be inferred at the class level: authentication bypass enables reaching a normally restricted server-side function that queries internal state and returns it in HTML or similar format. The sensitive data disclosed includes:

• Internal IP addresses (network topology mapping)
• Usernames (account enumeration)
• Store names (facility identification)
• Other sensitive information (generalized operational data)

The authentication flaw may be attributable to one of several common classes: missing authentication checks on specific routes, improper handling of user-controlled session indicators (e.g., a cookie checked only for presence, not validity), or default credentials being accepted. Without additional CNA disclosures, the precise mechanism remains unverified. Insufficient technical detail is available to confirm the exact code-level flaw.

The EPSS score of 0.00518 (41.3% percentile) indicates low general exploitation likelihood in the wild, but this metric reflects reporting coverage, not the severity of impact in exposed environments.

Exploitation Scenarios

No public PoC exists, and no Nuclei template or exploit code has been released. The following attack chain is inferred from the vulnerability class (authentication bypass leading to information disclosure) and is not a confirmed step-by-step methodology.

Step 1 — Reconnaissance / Target Identification An attacker identifies Danfoss AK-SM800A devices through internet-wide scanning of common building-automation ports (e.g., HTTP/HTTPS on non-standard ports, or UDP discovery services used by BACnet and similar protocols). Shodan queries targeting the vendor banner ("Danfoss") or the model string ("AK-SM800A") can surface exposed management interfaces. Since the device is an embedded controller, it may be reachable on corporate networks, VPN gateways, or directly on the internet if improperly segmented.

Step 2 — Triggering the Authentication Flaw The attacker requests the web-report generation feature without supplying valid credentials, or supplies partial/invalid credentials that fail to prevent access due to the authentication flaw. Because the flaw is in authentication, the attacker does not need to brute-force credentials. The request may be a simple HTTP GET or POST designed to invoke report generation.

Step 3 — Payload / Execution Method At the vulnerability-class level, the attacker abuses the missing/inadequate authentication check by directly requesting the report-generating resource. No payload in the traditional injection sense is required — the attack is a request to an unprotected endpoint. The response is a dynamically generated web report populated with backend data. The attacker does not need to inject malicious input; the flaw is in the server-side authorization check.

Step 4 — Post-Exploitation Impact The report discloses:

• Internal IP addresses — enabling network mapping and targeted lateral movement toward other OT assets.
• Usernames — providing valid account names for credential-stuffing or brute-force campaigns against the same device or other systems where users reuse credentials.
• Store names / facility identifiers — enabling physical-world targeting or social engineering of on-site staff.
• Other sensitive information — potentially including firmware versions, controller configuration, and network segmentation details that aid further exploitation.

In a worst-case escalation, the disclosed usernames could be paired with known default credentials for Danfoss equipment, or the internal network details could be used to pivot toward other controllers in the refrigeration system, causing operational disruption (e.g., disabling cooling systems) — though this goes beyond the direct scope of this CVE.

Impact Assessment

CVSS Analysis (Score: 7.5 — High). The scoring reflects a serious confidentiality impact. The vector components are unavailable in the provided data, but the score is consistent with an attack requiring network access, low attack complexity, and no privileges, yielding high confidentiality impact with limited availability/integrity impact. The authentication bypass provides an entry point with no user interaction required.

Business Impact.

• Data confidentiality: Exposure of internal network topology, user accounts, and facility operations data creates a foundation for broader network compromise.
• Operational technology risk: The AK-SM800A controls refrigeration; disclosed data may weaken the OT boundary, enabling later attacks that tamper with temperature controls (economic loss, food safety, compliance violations).
• Regulatory: Depending on jurisdiction, exposure of facility operations data and user credentials may trigger data-breach notification obligations, especially if store names and usernames map to consumer-facing retail operations.
• Reputation: A compromise of a refrigeration monitoring system in a grocery or pharma chain could be publicized as an OT security failure.

Blast Radius. The direct blast radius is limited to the AK-SM800A device and its web interface. However, the disclosed internal IPs and usernames expand the effective blast radius to the entire internal network segment where the controller resides, which may include point-of-sale systems, corporate IT servers, and other building-automation gear. The patch confidence of 2/4 (claimed but unconfirmed) means many deployed devices may remain vulnerable for an extended period.

Detection Guidance

The following detection rules are designed to identify attempts to access the web-report generation feature on the AK-SM800A or to detect successful information disclosure. Because no PoC or specific endpoint paths are public, the rules target anomalous access patterns and known device characteristics. These rules are generic — tune them to your environment once specific endpoint paths are confirmed by the vendor.

Sigma Rule

title: Danfoss AK-SM800A Authentication Bypass - Web Report Request
id: 5f6a8e21-73d4-4e0b-9f11-c1a7d09d5e7b
status: experimental
description: Detects unauthenticated or suspicious requests to Danfoss AK-SM800A web report generation, indicating possible CVE-2023-25913 exploitation
author: Valtersit Threat Intelligence
date: 2024/01/15
tags:
    - attack.initial-access
    - attack.t1190
    - cve.2023-25913
logsource:
    category: webserver
    product: apache
    definition: 'Requires web server access logs for the Danfoss AK-SM800A management interface'
detection:
    selection_auth:
        cs-method:
            - 'GET'
            - 'POST'
        cs-uri-extension:
            - '.html'
            - '.aspx'
            - '.cgi'
    selection_noauth:
        cs-username: '-'
    selection_path:
        cs-uri-query|contains:
            - 'report'
            - 'export'
            - 'generate'
    condition: selection_auth and selection_noauth and selection_path
falsepositives:
    - Legitimate unauthenticated status pages on the device
    - Misconfigured monitoring systems polling the device
level: high

YARA Rule

rule Danfoss_AK_SM800A_Report_Exfil
{
    meta:
        author = "Valtersit Threat Intelligence"
        description = "Detects web responses from Danfoss AK-SM800A potentially disclosing internal IPs, usernames, or store names"
        cve = "CVE-2023-25913"
        date = "2024-01-15"
        severity = "high"
    strings:
        $s1 = "AK-SM800A" ascii wide nocase
        $s2 = "store" ascii wide nocase
        $s3 = "username" ascii wide nocase
        $s4 = "192.168." ascii wide
        $s5 = "10." ascii wide
        $s6 = "report" ascii wide nocase
        $s7 = "user" ascii wide nocase
    condition:
        uint16be(0) == 0x3C68 or  // <h in HTML header
        uint32be(0) == 0x3C68746D or // <htm
        ($s1 or $s6) and
        (($s2 or $s3) and ($s4 or $s5) and $s7) and
        filesize < 2MB
}

Suricata IDS Rule

alert http any any -> $HOME_NET any (
    msg:"ET EXPLOIT Danfoss AK-SM800A Authentication Bypass Attempt (CVE-2023-25913)";
    flow:established,to_server;
    content:"GET"; http_method;
    content:"report"; http_uri;
    content:"Host"; nocase;
    http_header_names;
    pcre:"/report|export|generate/i";
    classtype:attempted-recon;
    sid:2023259131;
    rev:1;
    reference:cve,2023-25913;
    metadata:created_at 2024_01_15, updated_at 2024_01_15;
)

Elastic Detection

// Look for unauthenticated requests to the report generation URI on the AK-SM800A
any where
  event.category == "web" and
  network.protocol == "http" and
  url.path like "*report*" and
  user.name == null and
  not source.ip in ["127.0.0.1"]

// Alert on web responses from the device containing internal IP disclosures
network where
  event.category == "web" and
  network.protocol == "http" and
  destination.ip == "DEVICE_IP_PLACEHOLDER" and
  http.response.body like "*192.168.*" or
  http.response.body like "*10.*" or
  http.response.body like "*store*username*"

Splunk SPL Query

index=web sourcetype=access_combined
| search uri_path="*report*" OR uri_path="*export*" OR uri_path="*generate*"
| eval is_authed = if(user!="-" OR user!="", "yes", "no")
| search is_authed="no"
| stats count by src_ip, dest_ip, uri_path, status
| where count > 5

Wazuh OSSEC Rule

<group name="danfoss,">
  <rule id="100253" level="10">
    <decoded_as>web-access</decoded_as>
    <match>report|export|generate</match>
    <regex>srcip="(\d+\.\d+\.\d+\.\d+)" user="-"</regex>
    <description>Possible CVE-2023-25913 authentication bypass attempt against Danfoss AK-SM800A: unauthenticated report request</description>
    <mitre>
      <id>T1190</id>
    </mitre>
    <group>attack.initial-access,attack.t1190,cve-2023-25913</group>
  </rule>
</group>

Mitigation & Patch Guidance

Patch Confidence: 2/4 (CLAIMED). The vendor (through the CNA) has claimed a patch is available in version 3.3, but this is based on a single source and has not been independently confirmed. The affected version ranges have not been publicly enumerated. Treat all AK-SM800A devices running firmware older than 3.3 as potentially vulnerable until the patch is verified.

1. Immediate Mitigations (until patch is applied)

• Isolate the AK-SM800A web interface from the corporate network and the internet. Apply strict firewall rules to allow only trusted administrative IP addresses (e.g., jump-box hosts) to reach the device's management port.
• If remote access is required, enforce a VPN with multi-factor authentication before users can reach the device network segment — do not expose the device directly on any interface.
• Disable the web-report feature if it is not operationally required, or restrict it via device-level access-control lists if the feature supports that configuration.
• Monitor access logs to the device for unauthenticated requests matching the report path patterns.

2. Patch / Upgrade Steps

• Download firmware version 3.3 from the official Danfoss support portal (validate the SHA-256 checksum against vendor-published hashes).
• Schedule a maintenance window — this is an OT device; firmware updates may cause a temporary loss of refrigeration monitoring.
• Back up current configuration before upgrading.
• Apply the firmware per the vendor's upgrade procedure (typically via the web interface or a local USB/serial connection).
• Post-upgrade, verify that unauthenticated report generation no longer works; confirm that login is required to access all report features.
• Contact Danfoss support directly to confirm that 3.3 is the correct patched version and to obtain a list of affected firmware versions, as the public advisory is incomplete.

3. Long-Term Hardening

• Segment OT networks (including building automation) from IT networks using a DMZ or gateway filtering device — the AK-SM800A should never be directly internet-reachable.
• Implement a configuration baseline for all AK-SM800A devices: disable unused web features, change all default credentials, enforce strong password policies.
• Enable centralized logging (syslog) on the device, if supported, and feed it into the existing SIEM; if not supported, use a network TAP or SPAN port to monitor traffic to/from the device.
• Apply the same authentication-bypass review to other Danfoss devices in your environment (e.g., AK-CC, AK-SM families), as similar flaws may exist beyond the AK-SM800A.
• Track this CVE for updates: subscribe to the NVD feed and the Danfoss security advisory page. When the CNA publishes affected version ranges, reassess and potentially prioritize patching over other lower-risk items.

References

1. NVD Entry — CVE-2023-25913: https://nvd.nist.gov/vuln/detail/CVE-2023-25913
2. Danfoss Product Page — AK-SM800A (referenced for device capabilities; advisory link not public): https://www.danfoss.com/en/products/das/controllers/dcs/sm800a/
3. CISA Known Exploited Vulnerabilities Catalog — CVE-2023-25913 is NOT listed (as of this report), indicating no confirmed in-the-wild exploitation via CISA tracking: https://www.cisa.gov/known-exploited-vulnerabilities-catalog
4. MITRE CVE Record: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-25913
5. EPSS Score Reference (FIRST.org): https://www.first.org/epss/

Threat Actor Activity Note: As of the publication date, there is no evidence of active exploitation campaigns tied to this CVE. The EPSS score of 0.00518 (41.3% percentile) indicates a low probability of exploitation in the near term. No exploit code has been publicly released, and the patch status (2/4 confidence) suggests limited security-research attention. However, given that the device is internet-exposed in many grocery and cold-chain deployments, an exploit release would likely lead to rapid weaponization due to trivial request-based exploitation.