CVE-2024-10439: Sun.net Ehrd Ctms Path Traversal Flaw

CVE-2024-10439 Overview

CVE-2024-10439 is an Insecure Direct Object Reference (IDOR) vulnerability in the Sunnet eHRD CTMS platform. The flaw allows unauthenticated remote attackers to modify a request parameter and retrieve arbitrary files uploaded by any user of the system. Because the application fails to validate that the requester is authorized to access the referenced object, sensitive documents stored within the platform are exposed over the network. The weakness is tracked under CWE-639: Authorization Bypass Through User-Controlled Key and was disclosed through Taiwan's TWCERT coordination center.

Critical Impact
Unauthenticated attackers can retrieve arbitrary user-uploaded files across the eHRD CTMS deployment, exposing potentially sensitive HR, training, and personnel data.

Affected Products

Sunnet eHRD CTMS (all versions prior to the vendor fix)
sun.net:ehrd_ctms deployments exposed to network traffic
Internet-reachable eHRD CTMS instances used for HR and training management

Discovery Timeline

2024-10-28 - CVE-2024-10439 published to the National Vulnerability Database
2025-09-25 - Last updated in NVD database

Technical Details for CVE-2024-10439

Vulnerability Analysis

The eHRD CTMS application exposes file download functionality that references uploaded objects through a predictable, user-controllable parameter. The server does not verify whether the authenticated session, or in this case the absence of one, has rights to retrieve the referenced resource. An attacker can iterate or guess identifiers and pull files belonging to any user of the platform. The advisory from TWCERT confirms that exploitation requires no authentication and no user interaction. Impact is limited to confidentiality, since the IDOR exposes file contents without granting integrity or availability impact on the underlying system.

Root Cause

The root cause is missing authorization enforcement on a file retrieval endpoint. The application trusts the supplied object reference and serves the corresponding file directly from storage. This pattern matches [CWE-639], where access decisions rely on user-controlled keys rather than server-side authorization checks tied to the session principal.

Attack Vector

The attack vector is network-based and requires only the ability to issue HTTP requests to the eHRD CTMS application. An attacker modifies the file identifier parameter in a download request and receives the targeted file. Because identifiers are typically sequential or enumerable, large-scale data harvesting is feasible with simple scripting.

No verified proof-of-concept code is published. Refer to the TWCERT Security Advisory and the TWCERT Incident Report for vendor-coordinated technical details.

Detection Methods for CVE-2024-10439

Indicators of Compromise

Sequential or non-sequential enumeration of the file identifier parameter on eHRD CTMS download endpoints within a short time window
Large volumes of HTTP 200 responses from file download URLs originating from a single source IP without prior authentication
Unauthenticated requests to file retrieval endpoints that historically required a valid session cookie

Detection Strategies

Inspect web server and application access logs for repeated requests to file download handlers with incrementing object identifiers
Alert on file retrieval responses where the session is absent or the requesting user is not the file owner
Correlate spikes in egress data volume from the eHRD CTMS host with anomalous request patterns

Monitoring Recommendations

Forward application and web server logs to a centralized SIEM and retain at least 90 days of history for forensic review
Baseline normal file download rates per user and source IP, then alert on deviations
Monitor authentication telemetry to detect file access patterns that bypass the login flow entirely

How to Mitigate CVE-2024-10439

Immediate Actions Required

Restrict network exposure of the eHRD CTMS application to trusted networks or via VPN until the vendor patch is applied
Contact Sunnet for the remediated build and apply it according to the TWCERT Security Advisory
Review web server logs for prior exploitation attempts and identify any files that may have been exfiltrated

Patch Information

Sunnet has coordinated remediation through TWCERT. Administrators should obtain the fixed release directly from the vendor and consult the TWCERT Incident Report for version details and upgrade instructions.

Workarounds

Place the application behind a web application firewall and block unauthenticated requests to file download endpoints
Enforce session validation at a reverse proxy layer so that file retrieval URLs require an authenticated cookie
Rotate or invalidate sensitive documents that may have been exposed prior to patching

bash

# Example WAF rule concept (ModSecurity) to require an authenticated session
# on the eHRD CTMS file download endpoint
SecRule REQUEST_URI "@beginsWith /ehrd/download" \
    "id:1004391,phase:1,deny,status:403,\
    chain,msg:'Block unauthenticated eHRD CTMS file access (CVE-2024-10439)'"
    SecRule &REQUEST_COOKIES:SESSIONID "@eq 0"