Summary
A high-severity vulnerability in the MQTT Broker component of certain D-Link E15, M32, R15, and R32 devices involves credentials associated with /etc/emDaemon/passwd being hard-coded or otherwise predictable. Because the MQTT service may be reachable remotely, an attacker could use these credentials to gain unauthorized access or interact with broker-managed data.
A high-severity vulnerability in the MQTT Broker component of certain D-Link E15, M32, R15, and R32 devices involves credentials associated with /etc/emDaemon/passwd being hard-coded or otherwise predictable. Because the MQTT service may be reachable remotely, an attacker could use these credentials to gain unauthorized access or interact with broker-managed data.
Affected context
The issue affects deployments of D-Link E15, M32, R15, and R32 devices where the MQTT Broker processes or relies on credentials stored in /etc/emDaemon/passwd. Risk is increased when the broker is exposed to untrusted networks and the embedded credentials are reusable, discoverable, or not rotated per device.
The issue affects deployments of D-Link E15, M32, R15, and R32 devices where the MQTT Broker processes or relies on credentials stored in /etc/emDaemon/passwd. Risk is increased when the broker is exposed to untrusted networks and the embedded credentials are reusable, discoverable, or not rotated per device.
Exploit preconditions
- Attack surface: MQTT Broker network service
- Required access: Network reachability to the exposed broker; valid or discoverable hard-coded credentials may be needed for authenticated operations
- Trigger point: Authentication or authorization handling involving credentials associated with
/etc/emDaemon/passwd - Why exploitation is possible: Credentials embedded in software or device configuration may be shared, predictable, or available to attackers, weakening the intended authentication boundary
- Attack surface: MQTT Broker network service
- Required access: Network reachability to the exposed broker; valid or discoverable hard-coded credentials may be needed for authenticated operations
- Trigger point: Authentication or authorization handling involving credentials associated with
/etc/emDaemon/passwd - Why exploitation is possible: Credentials embedded in software or device configuration may be shared, predictable, or available to attackers, weakening the intended authentication boundary
Why this happens
The underlying issue is the use of hard-coded credentials in a network-facing component. This insecure pattern can cause the same secret, or a secret that is otherwise predictable or difficult to rotate, to be trusted across devices or deployments. It maps primarily to CWE-798: Use of Hard-coded Credentials, with CWE-259: Use of Hard-coded Password describing the related credential-handling weakness.
The underlying issue is the use of hard-coded credentials in a network-facing component. This insecure pattern can cause the same secret, or a secret that is otherwise predictable or difficult to rotate, to be trusted across devices or deployments. It maps primarily to CWE-798: Use of Hard-coded Credentials, with CWE-259: Use of Hard-coded Password describing the related credential-handling weakness.
Potential impact
- An attacker may authenticate to the MQTT Broker without authorization
- Unauthorized users could read, publish, or modify broker-managed messages, depending on permissions
- Device or application data could be exposed or manipulated
- Compromised broker access could support lateral movement into connected services
- Attackers could disrupt MQTT-based device and automation workflows
- An attacker may authenticate to the MQTT Broker without authorization
- Unauthorized users could read, publish, or modify broker-managed messages, depending on permissions
- Device or application data could be exposed or manipulated
- Compromised broker access could support lateral movement into connected services
- Attackers could disrupt MQTT-based device and automation workflows
General mitigation guidance
Mitigation generally focuses on removing shared embedded secrets and strengthening the broker's authentication boundary.
Common defensive patterns include:
- Generate unique credentials per device or installation
- Store secrets in protected, externally managed credential stores rather than in firmware or static files
- Require credential rotation and provide a secure recovery process
- Apply least-privilege permissions to MQTT users and topics
- Avoid exposing the broker directly to untrusted networks
- Use encrypted transport and enforce strong authentication where supported
- Restrict access to sensitive credential files and protect them from unauthorized modification or disclosure
Mitigation generally focuses on removing shared embedded secrets and strengthening the broker's authentication boundary.
Common defensive patterns include:
- Generate unique credentials per device or installation
- Store secrets in protected, externally managed credential stores rather than in firmware or static files
- Require credential rotation and provide a secure recovery process
- Apply least-privilege permissions to MQTT users and topics
- Avoid exposing the broker directly to untrusted networks
- Use encrypted transport and enforce strong authentication where supported
- Restrict access to sensitive credential files and protect them from unauthorized modification or disclosure
How teams detect issues like this
Organizations can look for this class of issue through:
- Static analysis and firmware review for embedded passwords, tokens, or credential-like strings
- Code review checks covering default accounts and secrets in source, images, and configuration files
- Scanning device inventories and MQTT endpoints for shared credentials or externally reachable services
- Monitoring authentication failures, unusual broker logins, unexpected topic subscriptions, and abnormal publishing activity
- Policy enforcement that blocks hard-coded secrets during build, packaging, and release processes
- Automated secret-scanning and software composition review tools used as neutral checks in development workflows
Organizations can look for this class of issue through:
- Static analysis and firmware review for embedded passwords, tokens, or credential-like strings
- Code review checks covering default accounts and secrets in source, images, and configuration files
- Scanning device inventories and MQTT endpoints for shared credentials or externally reachable services
- Monitoring authentication failures, unusual broker logins, unexpected topic subscriptions, and abnormal publishing activity
- Policy enforcement that blocks hard-coded secrets during build, packaging, and release processes
- Automated secret-scanning and software composition review tools used as neutral checks in development workflows
Sources
| Source | Link |
|---|---|
| github. | github.com/ |
| github. | github.com/ |
| vuldb. | vuldb.com/ |
| vuldb. | vuldb.com/ |
| vuldb. | vuldb.com/ |
| vuldb. | vuldb.com/ |
| dlink. | dlink.com/ |
