CVE-2006-1538 in X-Wall ASIC
Summary
by MITRE
The Enova X-Wall ASIC encrypts with a key obtained via Microwire from a serial EEPROM that stores the key in cleartext, which allows local users with physical access to obtain the key by reading and duplicating an EEPROM that is located on a hardware token, or by sniffing the Microwire bus.
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Analysis
by VulDB Data Team • 09/08/2017
The vulnerability described in CVE-2006-1538 represents a critical weakness in the cryptographic security implementation of the Enova X-Wall ASIC hardware token. This device employs a hardware-based encryption solution that relies on a secret key stored in a serial EEPROM component accessible through the Microwire interface. The fundamental flaw lies in the cleartext storage of the encryption key within the EEPROM, creating an exploitable condition that directly violates established cryptographic security principles. The vulnerability demonstrates a clear failure in implementing proper key management practices, where sensitive cryptographic material is stored without adequate protection mechanisms.
The technical exploitation of this vulnerability occurs through two primary attack vectors that leverage physical access to the hardware token. The first vector involves direct reading of the serial EEPROM component, which allows attackers to extract the encryption key in its unencrypted form. This approach directly relates to CWE-310, which addresses cryptographic issues including weak key storage and insufficient key protection mechanisms. The second exploitation method involves passive monitoring of the Microwire bus interface, where network sniffing techniques can capture the key transmission during the read process. This attack vector demonstrates the lack of secure communication protocols during key retrieval operations and aligns with CWE-319, which covers the exposure of sensitive information through improper transmission.
The operational impact of this vulnerability extends beyond simple key theft, as it fundamentally compromises the security model of the entire hardware token system. Local users with physical access can not only obtain the encryption key but also duplicate the hardware token, effectively creating unauthorized copies of the secure device. This capability enables attackers to bypass the intended security controls and potentially gain access to encrypted data or systems protected by the compromised token. The vulnerability creates a persistent threat that remains active as long as the physical hardware token exists, making it particularly dangerous in environments where physical security controls may be insufficient or compromised.
From an attack framework perspective, this vulnerability aligns with several techniques documented in the MITRE ATT&CK framework, particularly those related to credential access and privilege escalation. The ability to extract cryptographic keys through physical access represents a form of credential theft that can be executed without network connectivity or complex software exploitation. The vulnerability also demonstrates poor security architecture design principles that would typically be addressed through proper key management protocols and secure hardware implementation practices. Organizations relying on this hardware token for security purposes face significant risk exposure, as the vulnerability essentially provides attackers with the means to completely subvert the cryptographic protection mechanisms that the device was designed to provide.
Recommended mitigations for this vulnerability include immediate replacement of affected hardware tokens with models implementing secure key storage mechanisms such as hardware security modules or secure enclaves that prevent cleartext key exposure. Organizations should also implement strict physical security controls to prevent unauthorized access to hardware tokens, combined with regular security assessments to identify similar vulnerabilities in other cryptographic hardware components. The remediation process should also involve updating security policies to address the specific threat vectors presented by physical access attacks and ensuring that all cryptographic key management practices follow established security standards and best practices.