CWE-329 - Generation of Predictable IV with CBC Mode
CWE-329 Medium
- Abstraction:
- Variant
- Structure:
- Simple
- Status:
- Draft
- Weakness Name
Generation of Predictable IV with CBC Mode
- Description
The product generates and uses a predictable initialization Vector (IV) with Cipher Block Chaining (CBC) Mode, which causes algorithms to be susceptible to dictionary attacks when they are encrypted under the same key.
CBC mode eliminates a weakness of Electronic Code Book (ECB) mode by allowing identical plaintext blocks to be encrypted to different ciphertext blocks. This is possible by the XOR-ing of an IV with the initial plaintext block so that every plaintext block in the chain is XOR'd with a different value before encryption. If IVs are reused, then identical plaintexts would be encrypted to identical ciphertexts. However, even if IVs are not identical but are predictable, then they still break the security of CBC mode against Chosen Plaintext Attacks (CPA).
- Common Consequences
Scope: Confidentiality
Impact: Read Application Data
Notes: If the IV is not properly initialized, data that is encrypted can be compromised and leak information.
- Related Weaknesses
- Release Date:
- 2006-07-19
- Latest Modification Date:
- 2023-06-29
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