COMMON WEAKNESS ENUMERATIONDraft

CWE-602

Client-Side Enforcement of Server-Side Security

The product is composed of a server that relies on the client to implement a mechanism that is intended to protect the server.

Soyutlama

Class

Yapı

Simple

Sömürü İhtimali

Medium

Problemi anla

Problem nedir?

The product is composed of a server that relies on the client to implement a mechanism that is intended to protect the server.

Genişletilmiş açıklama

When the server relies on protection mechanisms placed on the client side, an attacker can modify the client-side behavior to bypass the protection mechanisms, resulting in potentially unexpected interactions between the client and server. The consequences will vary, depending on what the mechanisms are trying to protect.

Kök neden

Problem nasıl ve ne zaman oluşur?

Yaşam döngüsü evresi

Architecture and Design

COMMISSION: This weakness refers to an incorrect design related to an architectural security tactic.

Yaşam döngüsü evresi

Architecture and Design

Consider a product that consists of two or more processes or nodes that must interact closely, such as a client/server model. If the product uses protection schemes in the client in order to defend from attacks against the server, and the server does not use the same schemes, then an attacker could modify the client in a way that bypasses those schemes. This is a fundamental design flaw that is primary to many weaknesses.

Risk

Başarılı sömürü neye yol açar?

Bypass Protection MechanismDoS: Crash, Exit, or Restart

Etkilenen güvenlik alanları: Access Control, Availability

Client-side validation checks can be easily bypassed, allowing malformed or unexpected input to pass into the application, potentially as trusted data. This may lead to unexpected states, behaviors and possibly a resulting crash.
Bypass Protection MechanismGain Privileges or Assume Identity

Etkilenen güvenlik alanları: Access Control

Client-side checks for authentication can be easily bypassed, allowing clients to escalate their access levels and perform unintended actions.

Savunma

Nasıl önlenir ve çözülür?

Architecture and Design

Mimari ve tasarım yaklaşımı

Detay
For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server. Even though client-side checks provide minimal benefits with respect to server-side security, they are still useful. First, they can support intrusion detection. If the server receives input that should have been rejected by the client, then it may be an indication of an attack. Second, client-side error-checking can provide helpful feedback to the user about the expectations for valid input. Third, there may be a reduction in server-side processing time for accidental input errors, although this is typically a small savings.

Architecture and Design

Mimari ve tasarım yaklaşımı

Detay
If some degree of trust is required between the two entities, then use integrity checking and strong authentication to ensure that the inputs are coming from a trusted source. Design the product so that this trust is managed in a centralized fashion, especially if there are complex or numerous communication channels, in order to reduce the risks that the implementer will mistakenly omit a check in a single code path.

Doğrulama

Nasıl tespit edilir?

Fuzzing

Use dynamic tools and techniques that interact with the software using large test suites with many diverse inputs, such as fuzz testing (fuzzing), robustness testing, and fault injection. The software's operation may slow down, but it should not become unstable, crash, or generate incorrect results.

Manual Analysis

Use tools and techniques that require manual (human) analysis, such as penetration testing, threat modeling, and interactive tools that allow the tester to record and modify an active session. These may be more effective than strictly automated techniques. This is especially the case with weaknesses that are related to design and business rules.