CWE-502Deserialization of Untrusted Data

Description

Common consequences· 3

• Integrity — Modify Application Data, Unexpected State
  Attackers can modify unexpected objects or data that was assumed to be safe from modification. Deserialized data or code could be modified without using the provided accessor functions, or unexpected functions could be invoked.
• Availability — DoS: Resource Consumption (CPU)
  If a function is making an assumption on when to terminate, based on a sentry in a string, it could easily never terminate.
• Other — Varies by Context
  The consequences can vary widely, because it depends on which objects or methods are being deserialized, and how they are used. Making an assumption that the code in the deserialized object is valid is dangerous and can enable exploitation. One example is attackers using gadget chains to perform unauthorized actions, such as generating a shell.

Potential mitigations· 5

• [Architecture and Design, Implementation]If available, use the signing/sealing features of the programming language to assure that deserialized data has not been tainted. For example, a hash-based message authentication code (HMAC) could be used to ensure that data has not been modified.
• [Implementation]When deserializing data, populate a new object rather than just deserializing. The result is that the data flows through safe input validation and that the functions are safe.
• [Implementation]Explicitly define a final object() to prevent deserialization.
• [Architecture and Design, Implementation]
• [Implementation]Avoid having unnecessary types or gadgets (a sequence of instances and method invocations that can self-execute during the deserialization process, often found in libraries) available that can be leveraged for malicious ends. This limits the potential for unintended or unauthorized types and gadgets to be leveraged by the attacker. Add only acceptable classes to an allowlist. Note: new gadgets are constantly being discovered, so this alone is not a sufficient mitigation.

Related CAPEC attack patterns· 1

Exploits (incoming)1

Compliance frameworks addressing this (incoming)25

(incoming)124

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Related by meaning· 6

Nearest entities by semantic similarity across the cs-graph corpus.