CVE-2024-41336

Executive Summary

CVE-2024-41336 describes a plaintext credential storage vulnerability affecting a broad range of DrayTek Vigor routers, including Vigor 165/166, 2620/LTE200, 2860/2925, 2862/2926, 2133/2762/2832, 2135/2765/2766, 2865/2866/2927, 2962/3910, and 3912. Affected devices store passwords in an unencrypted, immediately readable format, which means any attacker who obtains access to the device's configuration storage or a backup file can recover administrative, VPN, Wi-Fi, or other service credentials. The NVD record does not provide a CVSS score, and as of the latest available data, there is no public exploit code, CISA KEV listing, or confirmed patch.

The risk is primarily an enabling vulnerability: plaintext password storage does not itself allow remote code execution, but it dramatically increases the impact of any other weakness that allows configuration file access, backup downloads, or local filesystem read. Enterprise security teams should prioritize restricting management access to DrayTek devices, monitoring for unauthorized configuration exports, and validating firmware versions against the fixed releases implied in the NVD description.

Technical Analysis

The NVD description for CVE-2024-41336 is a device-level statement rather than a code-level disclosure. It states that multiple DrayTek Vigor models store passwords in plaintext. No affected file paths, user account types, or cryptographic implementation details are provided, and the CNA title is empty. Because the description is sparse, technical analysis must be anchored to the vulnerability class: unprotected storage of credentials (CWE-256).

In a typical router firmware implementation, device credentials are persisted in a configuration database, NVRAM partition, or exportable configuration file. When passwords are stored in plaintext, the confidentiality of those credentials depends entirely on access-control mechanisms around the storage medium. Any flaw that permits an attacker to read the device's configuration — such as a separate command injection vulnerability, an authentication bypass, physical access, or a publicly exposed configuration backup endpoint — immediately exposes all stored secrets in a human-readable form.

The attack surface is therefore twofold:

• Local / administrative surface: An attacker with existing low-privilege access to the device management interface, or with physical access, can retrieve the plaintext password data without further cryptanalysis.
• Network / remote surface: If the device supports remote configuration backup or remote management over the internet, an attacker who can authenticate or bypass authentication may be able to download a configuration file containing the plaintext credentials.

Importantly, the vulnerability is not remotely triggerable by a single HTTP request in the absence of another control failure. The plaintext storage makes credential exfiltration trivial once the attacker has already reached the configuration storage layer. Because no specific protocol, endpoint, or parameter names are disclosed in the NVD source data, no deeper code-level trace can be produced without risking speculation.

The affected product list spans multiple hardware generations and firmware branches. This indicates that the plaintext storage behavior is likely systemic to the firmware family rather than an isolated regression in a single model. The firmware versions listed as "prior to" represent the vulnerable population; however, patch confidence is currently 0/4, meaning no independent confirmation that these newer firmware versions fully remediate the issue is available from tracked patch sources.

Exploitation Scenarios

No public PoC for CVE-2024-41336 is available, and the NVD description does not specify an attack vector. The following attack chain is inferred from the vulnerability class and should be treated as an enabling scenario rather than a confirmed exploit flow.

1. Reconnaissance / target identification:
   An attacker identifies internet-exposed DrayTek devices using device fingerprinting — for example, banner strings, HTTP titles containing "Vigor" or "DrayTek", or default administrative interface ports. Shodan-style search queries can reveal devices with remote management enabled.

2. Triggering the flaw class:
   The plaintext storage vulnerability is not triggered by a single malicious request. The attacker must first obtain access to the configuration storage. This can occur through:

   • An unrelated vulnerability in the web management interface
   • Default or weak administrative credentials
   • A publicly accessible configuration backup export
   • Physical access to the device storage
   • A successful command injection or file read vulnerability in the firmware

3. Payload / execution method at the vulnerability-class level:
   Once read access is obtained, the attacker retrieves the configuration file or device storage contents. Because passwords are stored in plaintext, no decryption, hash cracking, or brute-force step is required. The attacker extracts fields containing administrative passwords, Wi-Fi pre-shared keys, PPPoE credentials, or other secrets directly from the data.

4. Post-exploitation impact:
   The harvested credentials can be used to:

   • Log into the device with full administrative privileges
   • Modify routing, DNS, or firewall rules to redirect traffic or enable remote access
   • Use recovered Wi-Fi credentials to join trusted wireless networks
   • Use PPPoE/ISP credentials to impersonate the organization on the upstream connection
   • Pivot to other network segments that the compromised device connects to

Given the absence of an assigned CVSS score and no public PoC, the most realistic exploitation path is through a chained attack: an initial low-severity access flaw becomes critical because it exposes plaintext administrative credentials.

Impact Assessment

The business impact of CVE-2024-41336 is primarily confidentiality-driven. The affected systems are edge network devices, and their configuration files typically contain credentials for multiple infrastructure layers: local device administration, wireless networks, uplink PPPoE authentication, VPN tunnels, SIP accounts, and potentially remote management services. Exposure of these credentials can lead to full network compromise beyond the router itself.

The scope of affected hardware is significant. The NVD description lists at least 19 distinct product identifiers spanning SMB, enterprise, and LTE gateway device families. These devices are commonly deployed at branch offices, retail locations, and small enterprise edge environments. An attacker who recovers plaintext credentials from one device may reuse them across an organization if the credentials are shared or reused elsewhere.

CVSS data is not available, so no subscore analysis can be performed from the NVD record. The EPSS score is 0.00410 with a 34.1% percentile, indicating that current exploit activity in the wild is not widely reported. This may change when more concrete exploitation details or a proof-of-concept are released.

The absence of a CISA KEV listing and the lack of confirmed vendor patch information suggest that this vulnerability has not yet been leveraged in known, tracked campaigns. However, the plaintext storage flaw lowers the barrier for credential theft significantly, and enterprises should treat it as a high-priority hardening item for affected device models.

Detection Guidance

The following detection content is written at the vulnerability-class level because the NVD description does not provide device-specific file paths, endpoint names, or log messages. Analysts should tune the signatures to their local DrayTek deployment and network architecture.

Sigma Rule

title: Suspicious DrayTek Configuration Backup Access
id: 8a2ff3c1-4d7e-4b6a-9e51-9d0a1c4b2e66
status: experimental
description: Detects HTTP requests that may indicate an attempt to retrieve a DrayTek router configuration file containing plaintext credentials.
references:
  - https://nvd.nist.gov/vuln/detail/CVE-2024-41336
author: Valters IT Threat Intelligence
logsource:
  category: webserver
  product: access_log
detection:
  selection:
    user_agent|contains:
      - 'curl'
      - 'wget'
      - 'python'
      - 'Go-http-client'
  url_keywords:
    - 'backup'
    - 'config'
    - 'export'
    - 'settings'
  condition: selection and url_keywords
falsepositives:
  - Legitimate administrator backup downloads
  - Automated network monitoring tools
level: medium

YARA Rule

rule DrayTek_Plaintext_Credential_Config
{
    meta:
        author = "Valters IT Threat Intelligence"
        description = "Detects DrayTek router configuration files or memory dumps containing plaintext password fields"
        cve = "CVE-2024-41336"
        date = "2025-01-01"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2024-41336"
    strings:
        $s1 = "password=" ascii nocase
        $s2 = "passwd=" ascii nocase
        $s3 = "pwd=" ascii nocase
        $s4 = "pppoe" ascii nocase
        $s5 = "wpa" ascii nocase
        $s6 = "DrayTek" ascii nocase
        $s7 = "Vigor" ascii nocase
    condition:
        filesize < 5MB
        and ($s6 or $s7)
        and 2 of ($s1, $s2, $s3)
        and 1 of ($s4, $s5)
}

Suricata IDS Rule

alert http any any -> any any (msg:"ET POLICY DrayTek Configuration Response with Plaintext Password Fields"; flow:established,to_client; content:"HTTP/1.1 200 OK"; http_header; content:"Vigor"; nocase; http.response_body; content:"password="; nocase; distance:0; within:200; content:"text/plain"; http.header; classtype:policy-violation; sid:2024133601; rev:1;)

Elastic Detection

file
| where event.action in ("open", "read") and
      process.name != null and
      file.name like "*backup*" and
      file.name like "*config*"
| add [ network
        | where process.name != null
      ]

Splunk SPL Query

sourcetype=access_combined OR sourcetype=apache_access
| where like(uri, "%backup%") OR like(uri, "%config%") OR like(uri, "%export%")
| table _time, clientip, method, uri, useragent, status
| sort -_time

Wazuh OSSEC Rule

<rule id="205627" level="10">
  <decoded>access.log</decoded>
  <match>backup|config|export</match>
  <regex>Vigor|DrayTek</regex>
  <description>DrayTek device configuration access detected - possible plaintext credential exfiltration</description>
  <group>policy-violation,cve-2024-41336,</group>
</rule>

Mitigation & Patch Guidance

Patch confidence for this CVE is 0/4 — no tracked source currently confirms a vendor patch. The NVD description implies fixed firmware versions for each affected model, but the absence of vendor advisory confirmation means that upgrade instructions should be verified directly with DrayTek.

1. Immediate mitigations:

   • Disable remote management of DrayTek devices from the public internet.
   • Restrict management interface access to trusted internal IP ranges or VPN endpoints only.
   • Change all device administrative passwords immediately if any configuration exposure is suspected.
   • Rotate credentials for any services whose passwords may be stored on the device, including Wi-Fi PSKs, PPPoE, VPN, and SIP accounts.
   • Block unauthenticated configuration backup requests at the edge firewall.

2. Patch / upgrade steps:

   • Contact DrayTek support or review the official firmware download portal for the fixed versions referenced in the NVD description, such as Vigor 165/166 v4.2.6, Vigor 2862/2926 v3.9.9.4, and other corresponding builds.
   • Apply firmware updates in a staged manner, testing on non-production devices first.
   • After upgrade, re-check that plaintext password strings are no longer present in configuration exports.

3. Long-term hardening:

   • Enforce unique, strong credentials for every DrayTek device.
   • Centralize device logging and monitor for unauthorized configuration access.
   • Use hardware or software inventory to ensure all edge devices run supported and patched firmware.
   • Consider replacing deprecated models that no longer receive vendor security updates.
   • Assume that any device exposed to the internet may have been impacted, and conduct a credential review for all associated accounts.

References

• NVD Entry: https://nvd.nist.gov/vuln/detail/CVE-2024-41336
• CVE.org Record: https://www.cve.org/CVERecord?id=CVE-2024-41336
• DrayTek Official Website (product and firmware portal): https://www.draytek.com
• CISA KEV Catalog: Not listed at the time of writing; no known exploit-in-the-wild evidence was available.

No known threat actor campaigns, exploit code releases, or CISA KEV additions currently reference this vulnerability. Detection rules should be treated as baseline heuristics until more specific technical details or a vendor advisory becomes available.