CVE-2018-21078 in Samsung
Summary
by MITRE
An issue was discovered on Samsung mobile devices with M(6.0), N(7.x), and O(8.0) software. The Contacts application allows attackers to originate video calls because SS (Supplementary Service) and USSD (Unstructured Supplementary Service Data) codes are improperly secured. The Samsung ID is SVE-2018-11469 (April 2018).
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Analysis
by VulDB Data Team • 10/07/2020
The vulnerability identified as CVE-2018-21078 represents a critical security flaw within Samsung's mobile operating systems affecting devices running Marshmallow 6.0, Nougat 7.x, and Oreo 8.0 versions. This issue resides within the Contacts application where attackers can exploit improper security controls over supplementary service and USSD code execution. The flaw stems from insufficient validation and authorization mechanisms that allow malicious actors to initiate video calls through unauthorized USSD sequences without proper user consent or authentication. This vulnerability specifically impacts Samsung's proprietary implementation of telephony services and demonstrates a failure in the proper isolation of privileged telephony functions within the mobile operating system framework.
The technical root cause of this vulnerability lies in the improper handling of USSD and SS code sequences within the telephony subsystem of Samsung's Android-based operating systems. These supplementary services typically require specific authorization and user confirmation before execution, but the Contacts application fails to enforce these security controls when processing certain code patterns. The vulnerability allows attackers to bypass normal telephony service restrictions by crafting specific USSD commands that trigger video call initiation directly from the contacts interface. This represents a classic case of insufficient input validation and privilege escalation within mobile telephony services, where the application fails to properly verify the legitimacy of USSD code execution requests.
The operational impact of this vulnerability extends beyond simple unauthorized call initiation to potentially enable more sophisticated attack vectors. Attackers can leverage this flaw to perform unauthorized video calls, which could lead to privacy violations, billing fraud, and potential social engineering opportunities. The vulnerability is particularly concerning because it operates at the application level within the Contacts service, making it accessible through normal user interaction patterns. This allows for both automated exploitation and manual attack scenarios where malicious actors could craft specific contact entries or use social engineering tactics to trigger the vulnerability. The exposure affects millions of Samsung devices and represents a significant privacy and security risk for users who may unknowingly trigger these unauthorized services.
Security mitigations for this vulnerability should focus on implementing proper input validation and authorization controls for USSD and SS code execution within telephony applications. System-level patches should enforce strict validation of all incoming USSD sequences and require explicit user confirmation before executing any privileged telephony services. The fix should align with industry standards such as CWE-20 for improper input validation and CWE-863 for incorrect authorization, while also addressing ATT&CK techniques related to privilege escalation and credential access. Organizations should implement network-level monitoring to detect unusual USSD code patterns and ensure that all telephony service applications enforce proper authorization checks before executing sensitive operations. Regular security updates and user education about the risks of interacting with unknown contact entries are essential components of a comprehensive defense strategy against this class of vulnerability.