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USSD Security — A Hidden Risk
Section 3: USSD Security — A Hidden Risk
While USSD has long been considered a utility feature for balance checks and service menus, its technical nature makes it an overlooked vector for security risks in modern mobile networks. Unlike apps or browser-based services that often come with user permission layers and encryption, USSD operates on a lower level — closer to the GSM protocol stack — and therefore carries several inherent vulnerabilities.
Inherent Security Risks in USSD
1. Lack of Authentication and Authorization
USSD messages do not inherently include authentication mechanisms. Once a code is dialed, the network executes the associated command without verifying the identity of the sender or checking whether the user is authorized to perform the requested action. This makes it possible for attackers to trigger sensitive operations on behalf of users.
2. No Encryption or Data Integrity
USSD operates over GSM signaling channels and transmits data in plaintext. This lack of encryption means any party with access to the GSM signaling layer (e.g., through a rogue base station or femtocell) could potentially intercept or manipulate USSD messages. This opens the door to man-in-the-middle (MITM) attacks, data leakage, and command tampering.
