Requirements needed for audit data retention, storing, archiving. Statement: Authenticate users and processes to ensure appropriate access control decisions both within and across domains.
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Rationale: Authentication is the process where a system establishes the validity of a transmission, message, or a means of verifying the eligibility of an individual, process, or machine to carry out a desired action, thereby ensuring that security is not compromised by an untrusted source. It is essential that adequate authentication be achieved in order to implement security policies and achieve security goals. Implications: Authentication service needed for users and application processes. Rationale: Authorization should be conducted as an explicit check, and as necessary even after an initial authentication has been completed.
Authorization depends not only on the privileges associated with an authenticated user, but also on the context of the request.
The time of the request and the location of the requesting user may both need to be taken into account. Implications: For particularly sensitive operations, authorization may need to invoke authentication again. Although authorization begins only after authentication has occurred, this requirement is not circular. Authentication is not binary—users may be required to present minimal such as a password or more substantial e. Rationale: Assume attackers will have source code also for closed source software.
Assume attackers will have complete design and network topologies.
Open security design promote cycle of improvement faster. Assume sensitive information regarding security measurements are leaked or sold. Implications: Do not document secrets and configuration policies settings in security designs.
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Never store secrets e. Involve internal and external SME to evaluate the strength and weakness of a security design. Security should always be tested by experts open or not. Periodically pentest the security implementation, use different companies instead of always the same. Statement: Check the return value of all non-void functions, and check the validity of all function parameters. The return value of non-void functions must be checked by each calling function, and the validity of parameters must be checked inside each function.
Rationale: This is possibly the most frequently violated principle. In the strictest interpretation, this rule means that even the return value of printf statements and file close statements must be checked. A case can be made, though, that if the response to an error would rightfully be no different than the response to success, there is no point in checking a return value.
This is often the case with calls to printf and close. In cases like these, it can be acceptable to explicitly cast the function return value to void — thereby indicating that the programmer explicitly and not accidentally decides to ignore a return value.
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The rule is then only violated if the cast is missing. In more dubious cases, a comment should be present to explain why a return value is irrelevant. In most cases, though, the return value of a function should not be ignored, especially if error return values must be propagated up the function call chain.
Standard libraries famously violate this rule with potentially grave consequences. See, for instance, what happens if you accidentally execute strlen 0 , or strcat s1, s2, -1 with the standard C string library.
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For this reason, most coding guidelines for safety critical software also forbid the use of all ansi standard headers like string. If the function are needed, they should be written separately, and made compliant with safety critical use. The enforcement of this principle make sure that exceptions are always explicitly justified and justifiable , with mechanical checkers flagging violations.
Often, it will be easier to comply with the rule than to explain why non-compliance is acceptable. Implications: Extra testing and programming effort:Function parameters should normal be verified for validity before being used. This rule especially applies to pointers: before dereferencing a pointer that is passed as a parameter the pointer must be checked for null. Consider automating security testing on software static and dynamic tests. Statement: Clearly delineate the physical and logical security boundaries governed by associated security policies.
Rationale: Information technology exists in physical and logical locations, and boundaries exist between these locations. An understanding of what is to be protected from external factors can help ensure adequate protective measures are applied where they will be most effective. Sometimes a boundary is defined by people, information, and information technology associated with one physical location.
Rationale: In accordance with the minimise attack surface and Defence in Depth principles, this compartmentalise principle keeps a sub-system, or logically grouped set of sub-systems, relatively self-contained such that compromise of one will not imply the compromise of another. Implications: Use defence in depth security principles in the security architecture. Sourcing of sub systems is easily possible when this principles is implemented correctly.
Eliminate or minimize dependencies between subsystems. This can result in using other generic security services like a separate identification or authentication service. Statement: Compile with all warnings enabled, in pedantic mode, and use one or more modern static source code analyzers. All code must compile with these setting without warnings. All code must be checked on each build with at least one, but preferably more than one, state-of-the-art static source code analyzer and should pass the analyses with zero warnings.
Rationale: There are several very effective static source code analyzers on the market today, and quite a few freeware tools as well.
There is no excuse for any serious software development effort not to make use of this technology. It should be considered routine practice, especially for critical software development. The rule of zero warnings applies even in cases where the compiler or the static analyzer gives an erroneous warning: if the compiler or the static analyzer gets confused, the code causing the confusion should be rewritten so that it becomes more trivially valid. Many have been caught in the assumption that a warning was likely invalid, only to realize much later that the report was in fact valid for less obvious reasons.
Static analyzers originally had a bad reputation due to the limited capabilities of early versions e. The early tools produced mostly invalid messages, but this is not the case for the current generation of commercial tools. The best static analyzers today are fast, and they produce selective and accurate messages.
Implications: Provide awareness trainings of developers continuously. Rationale: Access rights are completely validated every time an access occurs. Systems should rely as little as possible on access decisions retrieved from a cache. The technique is less evident when applied to email, which must pass through separately applied packet filters, virus filters, and spam detectors.
Implications: Document decisions regarding use of cached data for security services. Usability aspects should be taken into account with setting cache invalidation timers. Rationale: The ability of security to support the mission of an organization may be limited by various factors, such as social issues. For example, security and workplace privacy can conflict. Commonly, security is implemented on an IT system by identifying users and tracking their actions.
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However, expectations of privacy vary and can be violated by some security measures. In some cases, privacy may be mandated by law. Implications: User awareness campaigns should be included in the security processes on regular basis. IT security measurements are a part of the total security system.
Thirteen principles to ensure enterprise system security
Organization processes en policies are of great importance. Rationale: Providing effective computer security requires a comprehensive approach that considers a variety of areas both within and outside of the computer security field. This comprehensive approach extends throughout the entire information life cycle. To work effectively, security controls often depend upon the proper functioning of other controls. Many such interdependencies exist.
If appropriately chosen, managerial, operational,and technical controls can work together synergistically. Implications: The effectiveness of security controls also depends on such factors as system management, legal issues, quality assurance, and internal and management controls.
Computer security needs to work with traditional security disciplines including physical and personnel security. Rationale: The responsibility and accountability3 of owners, providers, and users of IT systems and other parties4 concerned with the security of IT systems should be explicit. Implications: Depending on the size of the organization, the computer security program may be large or small, even a collateral duty of another management official.
However, even small organizations can prepare a document that states organization policy and makes explicit computer security responsibilities. Rationale: The costs and benefits of security should be carefully examined in both monetary and nonmonetary terms to ensure that the cost of controls does not exceed expected benefits. Security should be appropriate and proportionate to the value of and degree of reliance on the IT systems and to the severity, probability, and extent of potential harm. Requirements for security vary, depending upon the particular IT system. Implications: Calculated the cost of damage against security measurements.
Consider using proven generic OSS security services when applicable. Rationale: Computers and the environments in which they operate are dynamic. System technology and users, data and information in the systems, risks associated with the system, and security requirements are ever-changing. Many types of changes affect system security: technological developments whether adopted by the system owner or available for use by others ; connection to external networks; a change in the value or use of information; or the emergence of a new threat.
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