CWE-328 可逆的单向哈希

Reversible One-Way Hash

结构: Simple

Abstraction: Base

状态: Draft

被利用可能性: unkown

基本描述

The product uses a hashing algorithm that produces a hash value that can be used to determine the original input, or to find an input that can produce the same hash, more efficiently than brute force techniques.

扩展描述

This weakness is especially dangerous when the hash is used in security algorithms that require the one-way property to hold. For example, if an authentication system takes an incoming password and generates a hash, then compares the hash to another hash that it has stored in its authentication database, then the ability to create a collision could allow an attacker to provide an alternate password that produces the same target hash, bypassing authentication.

相关缺陷

• cwe_Nature: ChildOf cwe_CWE_ID: 326 cwe_View_ID: 1000

• cwe_Nature: ChildOf cwe_CWE_ID: 327 cwe_View_ID: 1000 cwe_Ordinal: Primary

适用平台

Language: {'cwe_Class': 'Language-Independent', 'cwe_Prevalence': 'Undetermined'}

常见的影响

可能的缓解方案

MIT-51 Architecture and Design

策略:

Use an adaptive hash function that can be configured to change the amount of computational effort needed to compute the hash, such as the number of iterations ("stretching") or the amount of memory required. Some hash functions perform salting automatically. These functions can significantly increase the overhead for a brute force attack compared to intentionally-fast functions such as MD5. For example, rainbow table attacks can become infeasible due to the high computing overhead. Finally, since computing power gets faster and cheaper over time, the technique can be reconfigured to increase the workload without forcing an entire replacement of the algorithm in use.
Some hash functions that have one or more of these desired properties include bcrypt [REF-291], scrypt [REF-292], and PBKDF2 [REF-293]. While there is active debate about which of these is the most effective, they are all stronger than using salts with hash functions with very little computing overhead.
Note that using these functions can have an impact on performance, so they require special consideration to avoid denial-of-service attacks. However, their configurability provides finer control over how much CPU and memory is used, so it could be adjusted to suit the environment's needs.

示例代码

例

In both of these examples, a user is logged in if their given password matches a stored password:

bad C

bad Java

This code uses the SHA-1 hash on user passwords, but the SHA-1 algorithm is no longer considered secure. Note this code also exhibits CWE-759 (Use of a One-Way Hash without a Salt).

分析过的案例

分类映射

相关攻击模式

• CAPEC-461
• CAPEC-68

引用

• REF-289 MD5 considered harmful today

• REF-62 The Art of Software Security Assessment

• REF-291 bcrypt

• REF-292 Tarsnap - The scrypt key derivation function and encryption utility

• REF-293 RFC2898 - PKCS #5: Password-Based Cryptography Specification Version 2.0

• REF-294 How To Safely Store A Password

• REF-295 How Companies Can Beef Up Password Security (interview with Thomas H. Ptacek)

• REF-296 Password security: past, present, future

• REF-297 Our password hashing has no clothes

• REF-298 Should we really use bcrypt/scrypt?

文章来源于互联网:scap中文网