Chi tiết CWE-329

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.

Chi tiết nền tảng

Các cách xuất hiện

Implementation : Developers might dismiss the importance of an unpredictable IV and choose an easier implementation to save effort, weakening the scheme in the process.

Nền tảng áp dụng

Ngôn ngữ

Lớp: Not Language-Specific (Undetermined)

Công nghệ

Lớp: ICS/OT (Undetermined)

Hậu quả phổ biến

Ví dụ đã quan sát

Các biện pháp giảm thiểu tiềm năng

Phases : Implementation
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.

Phương pháp phát hiện

Automated Static Analysis

Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)
Hiệu quả : High

Ghi chú ánh xạ lỗ hổng

Lý do : This CWE entry is at the Variant level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities.
Bình luận : Carefully read both the name and description to ensure that this mapping is an appropriate fit. Do not try to 'force' a mapping to a lower-level Base/Variant simply to comply with this preferred level of abstraction.

Ghi chú

As of CWE 4.5, terminology related to randomness, entropy, and predictability can vary widely. Within the developer and other communities, "randomness" is used heavily. However, within cryptography, "entropy" is distinct, typically implied as a measurement. There are no commonly-used definitions, even within standards documents and cryptography papers. Future versions of CWE will attempt to define these terms and, if necessary, distinguish between them in ways that are appropriate for different communities but do not reduce the usability of CWE for mapping, understanding, or other scenarios.

Tài liệu tham khảo

REF-62

The Art of Software Security Assessment
Mark Dowd, John McDonald, Justin Schuh.

REF-18

The CLASP Application Security Process
Secure Software, Inc..
https://cwe.mitre.org/documents/sources/TheCLASPApplicationSecurityProcess.pdf

REF-1171

Why IND-CPA implies randomized encryption
Matthew Green.
https://blog.cryptographyengineering.com/why-ind-cpa-implies-randomized-encryption/

REF-1172

Recommendation for Block Cipher Modes of Operation
NIST.
https://nvlpubs.nist.gov/nistpubs/Legacy/SP/nistspecialpublication800-38a.pdf

Gửi

Sửa đổi