CVE-2018-5717 in S2 Dispenser Controller
Summary
by MITRE
Memory write mechanism in NCR S2 Dispenser controller before firmware version 0x0108 allows an unauthenticated user to upgrade or downgrade the firmware of the device, including to older versions with known vulnerabilities.
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Analysis
by VulDB Data Team • 01/15/2020
The vulnerability identified as CVE-2018-5717 resides within the NCR S2 Dispenser controller firmware ecosystem, specifically targeting devices operating with firmware versions prior to 0x0108. This security flaw represents a critical weakness in the device's firmware update mechanism that fundamentally undermines the integrity and security posture of the dispensing system. The vulnerability manifests through an insufficient authentication mechanism that permits any unauthenticated user to manipulate the firmware upgrade process, creating a significant attack surface that adversaries can exploit to compromise the device's operational integrity.
The technical implementation of this vulnerability stems from a flawed memory write mechanism that lacks proper authentication checks during firmware update operations. This weakness allows attackers to perform unauthorized firmware modifications including both upgrades and downgrades to previous firmware versions. The mechanism does not validate the authenticity of the firmware source or require any form of cryptographic verification, making it susceptible to man-in-the-middle attacks and unauthorized firmware injection. The flaw essentially provides an unrestricted pathway for firmware manipulation that bypasses all normal security controls and validation procedures.
From an operational impact perspective, this vulnerability creates a severe risk landscape for organizations relying on NCR S2 Dispenser controllers for financial transactions and automated dispensing operations. Attackers can downgrade firmware to versions containing known vulnerabilities, effectively rolling back security improvements and exposing the device to previously patched exploits. This capability enables adversaries to maintain persistent access to the device while evading detection mechanisms that might be present in newer firmware versions. The vulnerability also undermines the device's ability to maintain secure communication protocols and can potentially allow for complete system compromise through subsequent exploitation of the downgraded firmware.
The vulnerability aligns with CWE-306, which addresses missing authentication for critical functions, and represents a clear violation of the principle of least privilege in firmware management operations. Organizations using affected devices face potential financial losses, data breaches, and operational disruptions as attackers can leverage this vulnerability to gain unauthorized control over dispensing systems. The attack vector is particularly concerning as it requires no prior authentication credentials, making it accessible to any individual with physical or network access to the device. This characteristic places the vulnerability in the ATT&CK framework under the T1072 Software Deployment Tools category, as it exploits legitimate firmware update mechanisms for malicious purposes.
Mitigation strategies should focus on immediate firmware updates to version 0x0108 or later, which address the authentication deficiencies in the memory write mechanism. Network segmentation and access controls should be implemented to limit physical and network access to affected devices. Organizations should also establish firmware integrity monitoring systems that can detect unauthorized firmware modifications and implement secure boot mechanisms to prevent downgrade attacks. Regular security assessments of dispensing systems and continuous monitoring of firmware versions are essential to maintain operational security and prevent exploitation of this vulnerability.