1814
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.
Relationships
The table(s) below shows the weaknesses and high level categories that are related to this
weakness. These relationships are defined as ChildOf, ParentOf, MemberOr and give insight to
similar items that may exist at higher and lower levels of abstraction. In addition, relationships such
as PeerOf and CanAlsoBe are defined to show similar weaknesses that may want to be explored.
Relevant to the view "Research Concepts" (CWE-1000)
Nature Type ID Name Page
ChildOf 328 Use of Weak Hash 806
ParentOf 759 Use of a One-Way Hash without a Salt 1585
ParentOf 760 Use of a One-Way Hash with a Predictable Salt 1589
Relevant to the view "Weaknesses for Simplified Mapping of Published
Vulnerabilities" (CWE-1003)
Nature Type ID Name Page
ChildOf 327 Use of a Broken or Risky Cryptographic Algorithm 799
Relevant to the view "Architectural Concepts" (CWE-1008)
Nature Type ID Name Page
MemberOf 1010 Authenticate Actors 2424
Relevant to the view "Software Development" (CWE-699)
Nature Type ID Name Page
MemberOf 255 Credentials Management Errors 2315
MemberOf 310 Cryptographic Issues 2318
Weakness Ordinalities
CWE Version 4.14
CWE-916: Use of Password Hash With Insufficient Computational Effort
CWE-916: Use of Password Hash With Insufficient Computational Effort