Overview
CVE-2025-34256 describes a critical vulnerability affecting Advantech WISE-DeviceOn Server versions prior to 5.4. This vulnerability stems from the use of a hard-coded cryptographic key, specifically a static HS512 HMAC secret, used for signing EIRMMToken JWTs (JSON Web Tokens) across all installations. This allows a remote, unauthenticated attacker to forge JWTs, impersonate any DeviceOn account, including the root super admin, and gain complete control over the DeviceOn instance.
Technical Details
The core issue is the usage of a static, pre-defined HMAC secret for signing JWTs. This violates fundamental security principles. Because the secret is the same for all installations, an attacker who discovers or obtains the key can use it to create valid JWTs. The server trusts these forged JWTs because they are signed with the known secret. An attacker needs only to include a valid email claim within the JWT to impersonate the corresponding user. Successful exploitation provides the attacker with full administrative privileges, including the ability to manage devices and execute arbitrary code on managed agents.
CVSS Analysis
Due to the severe impact, a high CVSS score is expected once it becomes available. The ability to remotely gain full administrative control without authentication warrants a critical severity rating.
CVSS Score: N/A (Awaiting official score, but anticipated to be Critical.)
Possible Impact
The exploitation of CVE-2025-34256 can have catastrophic consequences:
- Full Administrative Control: Attackers gain complete control over the WISE-DeviceOn Server instance.
- Data Breach: Sensitive data stored within the system can be accessed and exfiltrated.
- Remote Code Execution: Attackers can execute arbitrary code on managed agents, potentially compromising the entire network.
- System Disruption: Attackers can disrupt operations by modifying device configurations, issuing malicious commands, or taking devices offline.
- Reputational Damage: A successful attack can severely damage the reputation of organizations using vulnerable versions of WISE-DeviceOn.
Mitigation or Patch Steps
The primary mitigation is to upgrade to Advantech WISE-DeviceOn Server version 5.4 or later. This version addresses the vulnerability by implementing proper cryptographic key management practices and eliminating the hard-coded key. Advantech strongly recommends applying this update immediately.
To mitigate risk before upgrading, consider the following (although these are not substitutes for patching):
- Network Segmentation: Isolate the WISE-DeviceOn Server on a segmented network to limit the potential impact of a compromise.
- Monitor Network Traffic: Monitor network traffic for suspicious activity, such as unusual login attempts or unauthorized device management commands.
- Restrict Access: Limit access to the WISE-DeviceOn Server to only authorized personnel.
References
Advantech Security Advisory
Advantech WISE-DeviceOn Documentation
VulnCheck Advisory
