Unnecessary Complexity in Protection Mechanism (Not Using 'Economy of Mechanism')
|ID: 637||Date: (C)2012-05-14 (M)2012-11-08|
|Type: weakness||Status: DRAFT|
|Abstraction Type: Class|
The software uses a more complex mechanism than necessary,
which could lead to resultant weaknesses when the mechanism is not correctly
understood, modeled, configured, implemented, or used.
Extended DescriptionSecurity mechanisms should be as simple as possible. Complex security
mechanisms may engender partial implementations and compatibility problems,
with resulting mismatches in assumptions and implemented security. A
corollary of this principle is that data specifications should be as simple
as possible, because complex data specifications result in complex
validation code. Complex tasks and systems may also need to be guarded by
complex security checks, so simple systems should be preferred.
Applicable PlatformsLanguage Class: All
Time Of Introduction
- Architecture and Design
|Other ||Other || |
|Architecture and Design || ||Avoid complex security mechanisms when simpler ones would meet
requirements. Avoid complex data models, and unnecessarily complex
operations. Adopt architectures that provide guarantees, simplify
understanding through elegance and abstraction, and that can be
implemented similarly. Modularize, isolate and do not trust complex
code, and apply other secure programming principles on these modules
(e.g., least privilege) to mitigate vulnerabilities. || || |
|CWE-637 ChildOf CWE-907 ||Category ||CWE-888 || |
Demonstrative Examples (Details)
- HTTP Request Smuggling (CWE-444) attacks are feasible because there
are not stringent requirements for how illegal or inconsistent HTTP headers
should be handled. This can lead to inconsistent implementations in which a
proxy or firewall interprets the same data stream as a different set of
requests than the end points in that stream.
- The IPSEC specification is complex, which resulted in bugs, partial
implementations, and incompatibilities between vendors.
- CVE-2007-6067 : Support for complex regular expressions leads to a resultant algorithmic complexity weakness (CWE-407).
- CVE-2007-1552 : Either a filename extension and a Content-Type header could be used to infer the file type, but the developer only checks the Content-Type, enabling unrestricted file upload (CWE-434).
- CVE-2007-6479 : In Apache environments, a "filename.php.gif" can be redirected to the PHP interpreter instead of being sent as an image/gif directly to the user. Not knowing this, the developer only checks the last extension of a submitted filename, enabling arbitrary code execution.
- CVE-2005-2148 : The developer cleanses the $_REQUEST superglobal array, but PHP also populates $_GET, allowing attackers to bypass the protection mechanism and conduct SQL injection attacks against code that uses $_GET.
For more examples, refer to CVE relations in the bottom box.
White Box Definitions None
Black Box Definitions None
- Jerome H. Saltzer Michael D. Schroeder .The Protection of Information in Computer
Systems. Proceedings of the IEEE 63. Published on September, 1975.
- Sean Barnum Michael Gegick .Economy of Mechanism. Published on 2005-09-13.