The system must encrypt and verify client-side session information (ViewState).
CAPEC-39: Manipulating Opaque Client-based Data Tokens: In circumstances where an application holds important data client-side in tokens (cookies, URLs, data files, and so forth) that data can be manipulated. If client or server-side application components reinterpret that data as authentication tokens or data (such as store item pricing or wallet information) then even opaquely manipulating that data may bear fruit for an Attacker.
CAPEC-74: Manipulating State: The adversary modifies state information maintained by the target software or causes a state transition in hardware. If successful, the target will use this tainted state and execute in an unintended manner.
CWE-642: External Control of Critical State Data: The software stores security-critical state information about its users, or the software itself, in a location that is accessible to unauthorized actors.
OWASP Top 10 A2:2017-Broken Authentication: Application functions related to authentication and session management are often implemented incorrectly, allowing attackers to compromise passwords, keys, or session tokens, or to exploit other implementation flaws to assume other users' identities temporarily or permanently.
PCI DSS v3.2.1 - Requirement 6.5.10: Address common coding vulnerabilities in software-development processes such as broken authentication and session management.