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Reliance on Obfuscation or Encryption of Security-Relevant Inputs without Integrity Checking

Incomplete Base
Structure: Simple
Description

This vulnerability occurs when an application uses obfuscation or encryption to hide security-sensitive data (like tokens or parameters) but fails to verify whether that data has been altered. Without integrity checks, the system cannot detect if an attacker has tampered with these inputs.

Extended Description

Applications often hide or encrypt client-side data that influences server-side decisions, such as user permissions or system state. However, if the server only decodes or de-obfuscates this data without verifying its authenticity, an attacker can systematically guess or modify values to elevate privileges, access sensitive information, or alter application behavior. Obfuscation and weak encryption are designed for confidentiality, not integrity—they cannot prevent tampering. To prevent this, developers must implement robust integrity checks like digital signatures or HMACs alongside any obfuscation or encryption. These mechanisms allow the server to confirm that the data hasn't been changed since it was originally issued. Relying solely on hiding data is insufficient; you must actively validate its trustworthiness before using it for security-critical operations.
Common Consequences 1
Scope: Integrity

Impact: Unexpected State

The inputs could be modified without detection, causing the product to have unexpected system state or make incorrect security decisions.
Potential Mitigations 4
Phase: Architecture and Design
Protect important client controllable tokens/parameters for integrity using PKI methods (i.e. digital signatures) or other means, and checks for integrity on the server side.
Phase: Architecture and Design
Repeated requests from a particular user that include invalid values of tokens/parameters (those that should not be changed manually by users) should result in the user account lockout.
Phase: Architecture and Design
Client side tokens/parameters should not be such that it would be easy/predictable to guess another valid state.
Phase: Architecture and Design
Obfuscation should not be relied upon. If encryption is used, it needs to be properly applied (i.e. proven algorithm and implementation, use padding, use random initialization vector, user proper encryption mode). Even with proper encryption where the ciphertext does not leak information about the plaintext or reveal its structure, compromising integrity is possible (although less likely) without the provision of the integrity service.
Observed Examples 1
CVE-2005-0039An IPSec configuration does not perform integrity checking of the IPSec packet as the result of either not configuring ESP properly to support the integrity service or using AH improperly. In either case, the security gateway receiving the IPSec packet would not validate the integrity of the packet to ensure that it was not changed. Thus if the packets were intercepted the attacker could undetectably change some of the bits in the packets. The meaningful bit flipping was possible due to the known weaknesses in the CBC encryption mode. Since the attacker knew the structure of the packet, they were able (in one variation of the attack) to use bit flipping to change the destination IP of the packet to the destination machine controlled by the attacker. And so the destination security gateway would decrypt the packet and then forward the plaintext to the machine controlled by the attacker. The attacker could then read the original message. For instance if VPN was used with the vulnerable IPSec configuration the attacker could read the victim's e-mail. This vulnerability demonstrates the need to enforce the integrity service properly when critical data could be modified by an attacker. This problem might have also been mitigated by using an encryption mode that is not susceptible to bit flipping attacks, but the preferred mechanism to address this problem still remains message verification for integrity. While this attack focuses on the network layer and requires an entity that controls part of the communication path such as a router, the situation is not much different at the software level, where an attacker can modify tokens/parameters used by the application.
Likelihood of Exploit

High

Applicable Platforms
Languages:
Not Language-Specific : Undetermined
Modes of Introduction
Architecture and Design
Implementation
Related Attack Patterns
Related Weaknesses
ChildOf: Insufficient Verification of Data Authenticity (CWE-345)