Description
The product uses a one-way cryptographic hash against an input that should not be reversible, such as a password, but the product uses a predictable salt as part of the input.
This makes it easier for attackers to pre-compute the hash value using dictionary attack techniques such as rainbow tables, effectively disabling the protection that an unpredictable salt would provide. It should be noted that, despite common perceptions, the use of a good salt with a hash does not sufficiently increase the effort for an attacker who is targeting an individual password, or who has a large amount of computing resources available, such as with cloud-based services or specialized, inexpensive hardware. Offline password cracking can still be effective if the hash function is not expensive to compute; many cryptographic functions are designed to be efficient and can be vulnerable to attacks using massive computing resources, even if the hash is cryptographically strong. The use of a salt only slightly increases the computing requirements for an attacker compared to other strategies such as adaptive hash functions. See CWE-916 for more details.
Potential Impact
Access Control
Bypass Protection Mechanism
Mitigations & Prevention
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, sinc
If a technique that requires extra computational effort can not be implemented, then for each password that is processed, generate a new random salt using a strong random number generator with unpredictable seeds. Add the salt to the plaintext password before hashing it. When storing the hash, also store the salt. Do not use the same salt for every password.
Detection Methods
- Automated Static Analysis High — 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 sea
Real-World CVE Examples
| CVE ID | Description |
|---|---|
| CVE-2008-4905 | Blogging software uses a hard-coded salt when calculating a password hash. |
| CVE-2002-1657 | Database server uses the username for a salt when encrypting passwords, simplifying brute force attacks. |
| CVE-2001-0967 | Server uses a constant salt when encrypting passwords, simplifying brute force attacks. |
| CVE-2005-0408 | chain: product generates predictable MD5 hashes using a constant value combined with username, allowing authentication bypass. |
Related Weaknesses
Frequently Asked Questions
What is CWE-760?
CWE-760 (Use of a One-Way Hash with a Predictable Salt) is a software weakness identified by MITRE's Common Weakness Enumeration. It is classified as a Variant-level weakness. The product uses a one-way cryptographic hash against an input that should not be reversible, such as a password, but the product uses a predictable salt as part of the input.
How can CWE-760 be exploited?
Attackers can exploit CWE-760 (Use of a One-Way Hash with a Predictable Salt) to bypass protection mechanism. This weakness is typically introduced during the Implementation phase of software development.
How do I prevent CWE-760?
Key mitigations include: 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 re
What is the severity of CWE-760?
CWE-760 is classified as a Variant-level weakness (Low-Medium abstraction). It has been observed in 4 real-world CVEs.