CriticalCVE-2020-8657

    EyesOfNetwork Use of Hard-Coded Credentials Vulnerability (CVE-2020-8657)

    Published In CISA KEV since Sources: CVE.org

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    What is affected, what to do

    CVE-2020-8657 in EyesOfNetwork 5.3 involves the use of a hardcoded API key, allowing an attacker to calculate or guess the admin access token. This vulnerability enables an attacker to gain full control of the instance and is actively exploited in ransomware campaigns. All installations of EyesOfNetwork 5.3 are affected. An immediate update to a secured version is crucial to mitigate this risk.

    The vulnerability is being actively exploited; treat it as a priority. The available sources name no fixed version. Check the vendor guidance in the references below. Immediate actions, mitigation and detection rules are in the runbook below.

    Affected
    • EyesOfNetwork eq 5.3-0..5.3-0

    Not sure whether and how you are affected? Ask a question about this vulnerability

    Metrics

    9.8

    Priority

    XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.

    Source: NVD, CVSS v3

    9.8

    CVSS v3

    Severity Critical on the scale from 0 to 10.

    Source: CVE.org

    91.9 %

    EPSS score

    High — model estimates ≥ 50% chance of real-world exploitation within 30 days.

    Source: FIRST EPSS, percentile 99.82

    Show all metrics
    Severity
    Critical
    Priority (0–325)

    The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first?

    Read in glossary
    228.71 Methodology
    Exploit maturity

    An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack.

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    actively exploited
    XIEM Effective CVSS

    XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command.

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    9.8 Methodology
    CVSS v3

    CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions.

    Read in glossary
    9.8
    EPSS score

    The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“.

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    91.9 %
    High — model estimates ≥ 50% chance of real-world exploitation within 30 days.
    EPSS percentile

    The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking.

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    99.82
    Critical — this CVE ranks in the top fifth of all CVEs scored today (rank ≥ 80%).
    KEV status

    The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.

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    Actively exploited
    Published
    In CISA KEV since

    The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.

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    CISA assessment (SSVC)
    Exploitation: active · automatable · Technical impact: total
    Source: CISA Vulnrichment, as of 4 February 2025
    CWE

    CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect.

    Read in glossary
    CWE-798

    Response and mitigation

    Why act now?

    Prioritisation rationale

    This CVE is on KEV because it is network-reachable without authentication and yields direct admin control over a monitoring platform — and EON servers by definition hold broad read and often write access across the monitored estate. Exploitation likelihood sits at the very top of the KEV catalogue, since the static API key is publicly known and the exploit is trivially scriptable. CISA does not flag active ransomware use, but in practice EON is abused as a lateral-movement pivot into OT-adjacent networks (SNMP sweeps, NRPE agents), which makes it critical for NIS2/KRITIS operators. Treat as P1 whenever an EON 5.3 instance exists; where perimeter exposure is already blocked, drop to P2 with a 30-day patch-or-replace deadline.

    1. Runbook step 1

      Immediate response (0-24 h)

      • Inventory all EyesOfNetwork 5.3-0 instances (web UI typically on 80/443, API path /eonapi/) and check whether the hard-coded EONAPI_KEY in include/api_functions.php is still at its default value. If yes, replace it immediately with a random value of at least 32 characters and reload Apache httpd.
      • Restrict external reachability of the EON web UI and API endpoint at the perimeter firewall or reverse proxy to admin VLANs / jump hosts only. EON is an internal monitoring tool and does not belong on the public internet.
      • Invalidate all existing admin access tokens (truncate the EON session table, restart apache2/httpd) and rotate admin passwords, since a derived token may already have been exfiltrated.
      • Verify whether EyesOfNetwork is still vendor-maintained — the project is largely dormant. Open a mid-term migration decision toward a maintained monitoring stack (Centreon, Icinga 2, Zabbix).
      • Preserve 180 days of web and API access logs (forensic copy of unauthorised /eonapi/ calls using admin tokens) before key rotation invalidates attacker tokens and removes correlation evidence.

    2. Runbook step 2

      Mitigation layers

      • Network segmentation: place EON in a dedicated management VLAN. Inbound traffic only from defined SOC/NOC workstations; outbound limited to monitored targets (SNMP, NRPE, SSH). No general internet egress from the EON host.
      • WAF/reverse proxy in front of EON: expose /eonapi/ only to source IPs from the admin network and front it with Basic Auth or mTLS so the vulnerable endpoint is unreachable without a second factor.
      • Configuration hardening: individualise EONAPI_KEY in include/api_functions.php per installation, set file permissions to 640 root:apache, and enable file-integrity monitoring (AIDE, Tripwire) on the include/ directory.
      • IAM/least privilege: constrain monitoring service accounts on target systems to read-only rights so a compromised EON cannot be used as a pivot for lateral movement via NRPE or shared SSH keys.
      • Keep encrypted, offline backups of the EON configuration database. On suspected compromise, rebuild rather than clean in place — webshells dropped into /usr/share/eyesofnetwork/ are commonly missed.

    3. Runbook step 3

      Detection rules

      • Apache access logs: look for GET /eonapi/ or POST /eonapi/ with user agents like python-requests, curl, Go-http-client from source IPs outside the known SOC scanner range. Example KQL: WebLogs | where cs_uri_stem startswith "/eonapi/" and c_useragent !in (knownAgents).
      • Sigma shape: selection: cs-uri-stem|startswith: "/eonapi/" AND sc-status: 200 AND cs-method: "POST" correlated with a subsequent admin action (new user created, host definition changed) within 60 seconds — classic token replay.
      • auditd on the EON host: watch include/api_functions.php and /etc/nagios/. Unexpected read or write events by processes other than apache/root indicate post-exploitation activity.
      • Process telemetry (Sysmon for Linux / EDR): httpd/apache2 as parent of /bin/sh, php, wget, curl, or nc is highly suspicious — EON does not spawn shells in normal operation.
      • Network (Zeek/Suricata): egress connections from the EON host to non-monitored destinations or Tor/pastebin domains. Suricata rule analogous to alert http any any -> any any (msg:"EON API admin token use from external"; content:"/eonapi/"; http_uri; sid:1000001;).

    Detection rules

    No NEOSEC detection rule is available for this vulnerability yet.

    Classification under NIS2 and CRA

    Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.

    NIS2

    NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management.

    Read in glossary
    Actively exploited: treat the vulnerability as a priority in vulnerability handling under Art. 21(2)(e) NIS2. If it is exploited in your environment, check the reporting obligation under Art. 23 (early warning within 24 hours).
    CRA

    The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates.

    Read in glossary
    Since 11.09.2026, manufacturers of affected products with digital elements must report actively exploited vulnerabilities under Art. 14 CRA, with an early warning within 24 hours via ENISA's single reporting platform.
    ISO/IEC 27001

    ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security.

    Read in glossary
    Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.

    Description

    An issue was discovered in EyesOfNetwork 5.3. The installation uses the same API key (hardcoded as EONAPI_KEY in include/api_functions.php for API version 2.4.2) by default for all installations, hence allowing an attacker to calculate/guess the admin access token.

    Source: NVD (NIST), cvelistv5, CISA KEV Catalog

    Affected products

    The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.

    Affected products
    Affected versionsFixed in
    eyesofnetworkeyesofnetwork
    • 5.3-0
    • —

    Vendors and products

    Weakness classes (CWE)

    • CWE-798Use of Hard-coded Credentials

      Base

      The product contains hard-coded credentials, such as a password or cryptographic key.

      Entry at MITRE CWE-798

    Public exploit references

    Publicly reported proof-of-concepts, exploit modules and detection templates for this vulnerability. NEOSEC links to the original sources only and does not provide any exploit code.

    Public exploit references
    CISA KEV CatalogCISA Known Exploited Vulnerability (opens in a new tab)cisa.govactively exploited
    Packet StormEyesOfNetwork AutoDiscovery Target Command Execution (opens in a new tab)packetstormsecurity.comPoC (publicly reported)reported, not verified—

    References & sources

    • github.comEyesOfNetworkCommunity/eonapi/issues/17x_refsource_MISC, Third-party advisory
    • packetstormsecurity.comfiles/156605/EyesOfNetwork-AutoDiscovery-Target-Command-Executi…x_refsource_MISC, Exploit, Third-party advisory, Vulnerability database
    • cisa.govknown-exploited-vulnerabilities-catalog?field_cve=CVE-2020-8657government-resource, US government resource
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