CWE-916: Use of Password Hash With Insufficient… | Glexia
CWE-916 (Use of Password Hash With Insufficient Computational Effort) weakness overview with consequences, detection methods, mitigations, related CVEs and MITRE…
Glexia's Take · Automated analysis
CWE-916: Use of Password Hash With Insufficient Computational Effort
Use of Password Hash With Insufficient Computational Effort represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.
Executive Impact
- Access Control: Bypass Protection Mechanism Gain Privileges or Assume Identity: If an attacker can gain access to the hashes, then the lack of sufficient computational effort will make it easier to conduct brute force attacks using techniques such as rainbow tables, or specialized hardware such as GPUs, which can be much faster than general-purpose CPUs for computing hashes.
Developer Pattern
CWE-916 is the kind of defect developers can usually prevent with explicit validation, safer framework defaults, and tests that exercise hostile input or unsafe state transitions.
Automation confidence
high confidence from CWE-916, 4.20.
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Official CWE Definition
CWE-916: Use of Password Hash With Insufficient Computational Effort
The product generates a hash for a password, but it uses a scheme that does not provide a sufficient level of computational effort that would make password cracking attacks infeasible or expensive.
Many password storage mechanisms compute a hash and store the hash, instead of storing the original password in plaintext. In this design, authentication involves accepting an incoming password, computing its hash, and comparing it to the stored hash. Many hash algorithms are designed to execute quickly with minimal overhead, even cryptographic hashes. However, this efficiency is a problem for password storage, because it can reduce an attacker's workload for brute-force password cracking. If an attacker can obtain the hashes through some other method (such as SQL injection on a database that stores hashes), then the attacker can store the hashes offline and use various techniques to crack the passwords by computing hashes efficiently. Without a built-in workload, modern attacks can compute large numbers of hashes, or even exhaust the entire space of all possible passwords, within a very short amount of time, using massively-parallel computing (such as cloud computing) and GPU, ASIC, or FPGA hardware. In such a scenario, an efficient hash algorithm helps the attacker. There are several properties of a hash scheme that are relevant to its strength against an offline, massively-parallel attack: The amount of CPU time required to compute the hash ("stretching") The amount of memory required to compute the hash ("memory-hard" operations) Including a random value, along with the password, as input to the hash computation ("salting") Given a hash, there is no known way of determining an input (e.g., a password) that produces this hash value, other than by guessing possible inputs ("one-way" hashing) Relative to the number of all possible hashes that can be generated by the scheme, there is a low likelihood of producing the same hash for multiple different inputs ("collision resistance") Note that the security requirements for the product may vary depending on the environment and the value of the passwords. Different schemes might not provide all of these properties, yet may still provide sufficient security for the environment. Conversely, a solution might be very strong in preserving one property, which still being very weak for an attack against another property, or it might not be able to significantly reduce the efficiency of a massively-parallel attack.
Developer And Remediation Guidance
How teams prevent and detect this weakness
Causes
- In this example, a new user provides a new username and password to create an account. The program hashes the new user's password then stores it in a database. While it is good to avoid storing a cleartext password, the program does not provide a salt to the hashing function, thus increasing the chances of an attacker being able to reverse the hash and discover the original password if the database is compromised. Fixing this is as simple as providing a salt to the hashing function on initialization: Note that regardless of the usage of a salt, the md5 hash is no longer considered secure, so this example still exhibits CWE-327.
Remediation
- Architecture and Design: 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.
- Implementation Architecture and Design: When using industry-approved techniques, use them correctly. Don't cut corners by skipping resource-intensive steps (CWE-325). These steps are often essential for preventing common attacks.
Detection
- Automated Static Analysis - Binary or Bytecode: According to SOAR [REF-1479], the following detection techniques may be useful: Cost effective for partial coverage: Bytecode Weakness Analysis - including disassembler + source code weakness analysis Binary Weakness Analysis - including disassembler + source code weakness analysis
- Manual Static Analysis - Binary or Bytecode: According to SOAR [REF-1479], the following detection techniques may be useful: Cost effective for partial coverage: Binary / Bytecode disassembler - then use manual analysis for vulnerabilities & anomalies
- Manual Static Analysis - Source Code: According to SOAR [REF-1479], the following detection techniques may be useful: Highly cost effective: Focused Manual Spotcheck - Focused manual analysis of source Manual Source Code Review (not inspections)
- Automated Static Analysis - Source Code: According to SOAR [REF-1479], the following detection techniques may be useful: Highly cost effective: Source code Weakness Analyzer Context-configured Source Code Weakness Analyzer
- Automated Static Analysis: According to SOAR [REF-1479], the following detection techniques may be useful: Cost effective for partial coverage: Configuration Checker
- Architecture or Design Review: According to SOAR [REF-1479], the following detection techniques may be useful: Highly cost effective: Formal Methods / Correct-By-Construction Cost effective for partial coverage: Inspection (IEEE 1028 standard) (can apply to requirements, design, source code, etc.)
Mappings
Related CVEs, CWEs, and ATT&CK context
Related CWEs
No related CWE relationships are published yet.
ATT&CK Relevance
ATT&CK relevance is shown only when reviewed or responsibly inferred.