CVE-2001-1436 in iButton
Summary
by MITRE
Dallas Semiconductor iButton DS1991 returns predictable values when given an incorrect password, which makes it easier for users with physical access to conduct dictionary attacks against the device password.
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Analysis
by VulDB Data Team • 11/17/2024
The Dallas Semiconductor iButton DS1991 represents a cryptographic hardware device designed for secure identification and authentication purposes, utilizing a 128-bit encryption algorithm to protect sensitive data stored on the device. This particular vulnerability arises from a fundamental flaw in the device's authentication mechanism where the system fails to properly handle incorrect password attempts. When an unauthorized user provides an incorrect password to the DS1991 device, the system does not maintain consistent response behavior but instead returns predictable values that can be exploited by attackers. This predictable response pattern fundamentally undermines the security model of the device and creates a significant weakness in its cryptographic implementation.
The technical flaw manifests as a timing and response inconsistency in the authentication process where the device's behavior becomes predictable when processing invalid credentials. This vulnerability directly relates to CWE-330 Use of Insufficiently Random Values, as the device fails to generate truly random responses during authentication failures. The predictable return values allow attackers to perform dictionary attacks by systematically trying various password combinations and observing the consistent responses from the device. This weakness enables attackers with physical access to the device to bypass the security protections through automated brute force or dictionary attack methodologies that would otherwise be ineffective against properly designed cryptographic systems.
The operational impact of this vulnerability extends beyond simple password guessing as it fundamentally compromises the integrity of the authentication mechanism for any system relying on the DS1991 device for security. Attackers with physical access can exploit this weakness to gain unauthorized access to data stored on the device, potentially compromising sensitive information that was intended to be protected by the device's cryptographic capabilities. The vulnerability is particularly concerning in environments where physical security is assumed but not properly enforced, as it allows for attacks that do not require sophisticated network-based techniques but rather simple physical access and basic knowledge of the device's behavior patterns. This weakness essentially provides attackers with a backdoor into the system through the predictable authentication failure responses.
Mitigation strategies for this vulnerability must address both the immediate security implications and the underlying design flaw in the device's authentication mechanism. Organizations should implement additional layers of security beyond the device's built-in protection, including physical security measures to prevent unauthorized access to the devices, network segmentation to limit exposure, and regular security audits to identify potentially compromised systems. The most effective long-term solution involves replacing affected DS1991 devices with newer models that properly implement cryptographic authentication mechanisms or implementing additional software-based protections that can detect and prevent dictionary attack patterns. Security professionals should also consider implementing monitoring systems that can detect anomalous authentication patterns that might indicate exploitation attempts against vulnerable devices. This vulnerability highlights the critical importance of proper cryptographic design and the necessity of thorough security testing for all authentication mechanisms, particularly those that may be subject to physical access attacks.