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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.
Modes of Introduction:
– Architecture and Design
Likelihood of Exploit: Medium
Related Weaknesses
CWE-1204
CWE-573
Consequences
Confidentiality: Read Application Data
If the IV is not properly initialized, data that is encrypted can be compromised and leak information.
Potential Mitigations
Phase: Implementation
Description:
NIST recommends two methods of generating unpredictable IVs for CBC mode [REF-1172]. The first is to generate the IV randomly. The second method is to encrypt a nonce with the same key and cipher to be used to encrypt the plaintext. In this case the nonce must be unique but can be predictable, since the block cipher will act as a pseudo random permutation.
CVE References
- CVE-2020-5408
- encryption functionality in an authentication framework uses a fixed null IV with CBC mode, allowing attackers to decrypt traffic in applications that use this functionality
- CVE-2017-17704
- messages for a door-unlocking product use a fixed IV in CBC mode, which is the same after each restart
- CVE-2017-11133
- application uses AES in CBC mode, but the pseudo-random secret and IV are generated using math.random, which is not cryptographically strong.
- CVE-2007-3528
- Blowfish-CBC implementation constructs an IV where each byte is calculated modulo 8 instead of modulo 256, resulting in less than 12 bits for the effective IV length, and less than 4096 possible IV values.
- CVE-2011-3389
- BEAST attack in SSL 3.0 / TLS 1.0. In CBC mode, chained initialization vectors are non-random, allowing decryption of HTTPS traffic using a chosen plaintext attack.
