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provides software and SaaS solutions for dynamic, black box testing of Web applications
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Web Application Security: The Truth about White Box Testing versus Black Box Testing
Box Testing is also known as :
Web Applications Testing,
Web Load Testing,
Web Test Automation,
Web Testing Software,
Web Testing Tool,
Web Testing Tools,
Website Testing Plan,
Website Testing Tools,
Website Usability Testing,
What is Software Testing,
Application Testing Software,
Application Testing Tool,
Application Testing Tools,
Automated Software Testing Tools,
Automated Test Software,
Automated Testing Tool,
Automated Testing Tools.
CISOs, Information security managers, quality assurance staff, and developers alike are faced
with the enormous responsibility of keeping Web applications secure from the ever growing
menace of hackers and internal threats alike. Newly surfacing threats are overwhelming
information security teams. With Web applications constantly evolving, finding vulnerabilities is a
challenging, costly and time-consuming undertaking.
How can information security personnel protect sensitive data – and ultimately, the corporate
reputation – without exhausting internal resources, overspending the budget or being forced to
use costly manual penetration testing using external consulting firms?
Security teams are dealing with this ominous challenge with a myriad of solutions, some highly
ineffective. However, as the market matures, companies are applying somewhat effective, but not
complete solutions like white box testing tools. Ultimately the challenges of architecture, API
usage, and integration prevent white box testing tools from having a truly direct impact on the
overall security of an application. It’s critical to understand that white box analysis tools do not
directly find all the risks inherent in applications—period.
This paper explores the role of white box vs. black box testing. White box testing technologies
have a definite but limited use and value. From a Web application security perspective it must be
understood that significant blind spots come with white box testing. Ultimately white box testing is
not sufficient to secure your applications: simply put organizations that rely solely on white box
technologies will be exposed to vulnerabilities in their applications, thus making it an ineffectual
method of testing real-world risks. This paper will demonstrate black box or dynamic testing is
ultimately the appropriate solution for “truly” securing Web applications.
White and Black Box Testing in the Software Development Lifecycle
The software development lifecycle is composed of design, build, deployment and operation. When mapping security needs to these process steps it is useful to keep in mind the factors
- Security Requirements: Security requirements must be built into application design
from the point of conceptual development (i.e. the white-board phase) and denote specific
functional characteristics of the application.
- Security Controls within Design: Security best-practices and security controls should
be instituted within the functional planning, design, and architecture phases, and formally
specified and considered prior to any actual development on the application. Use of
application security checklists provide a baseline for needed security mechanisms while also
providing a security awareness tool for developers.
- Build: When actual coding and implementation begins, the process should be governed
by the specific security requirements specified in the earlier stages of the SDLC process.
- Integration testing: Test-cases should be developed that demonstrate characteristics
as defined by the security requirements, design requirements, and coding practices of the
organization. Security testing prior to application release should involve specific Web security
vulnerability tests, to ensure that the application is resistant to common types of attack and
real-world attack scenarios.
- Deployment: Security testing in a staging environment that mirrors the production
environment must be performed at this stage. The suite of tests must be carried forward from
integration testing. A subset of these tests that are non-invasive should be carried forward to
the operations and maintenance phase.
- Operations and Maintenance: Once deployed, applications should be frequently
assessed for vulnerabilities while they are in production.
|White Box Testing
||Run for each major milestone
|Black Box Testing
||Run with each build
||Run with each build
||Run with each build
||Run with each change management procedure
White Box Testing: An Overview
Source code analysis tools are commonly called “white box” technologies because they have
visibility into the source code that comprises applications. White box testing tools (source code
analysis tools) look for the use of insecure functions and other bugs by inspecting the raw
application source code.
Similar to a spelling and grammar checking tool built into a word processor, they operate both on
the basis of a signature set for known bad functions (words) and a rule set for identifying
sentence-level patterns (code grammar). Source code analysis tools automate the analysis of the
code by finding code errors that result in vulnerabilities. They also target bad programming
practices. When used during the development cycle they can help to eliminate common
These technologies have clear but limited benefit for a security program, but it is important to
understand their true use.
By using white box testing early in the development life cycle, organizations can eliminate
security vulnerabilities before they are deployed in a live system.
White box testing tools have the following benefits:
- Reduced faulty code base.
Proactive use of white box technologies during the development cycle can minimize the risk
of producing faulty code under tight deadlines.
- Education of developers in secure coding practices.
Using white box testing tools can help to educate the developers to avoid the use of insecure
- Automation of the repetitive aspects of source code analysis.
Repetitive tasks when performed by humans often result in errors slipping through or being
overlooked. White box testing tools can automate the task of sanity checking code so that
fewer mistakes are made. This frees up a developer to focus on the code rather than
analyzing code line-by-line for security vulnerabilities.
- Conformity with internal security standards.
Organizations can use white box testing tools to enforce good coding practices and
conformance with their own internal coding standards and guidelines.
- Improve the security legacy code.
Some pieces of code used by an organization may have originated by developers that are no
longer with the organization. Additionally, this code may not be very well understood. White
box testing can be used on legacy code to find and fix some basic vulnerabilities much
quicker than a manual review of a legacy code-base.
Organizations must understand the importance of black box testing to truly secure their Web
applications. While white box testing looks inside a Web application at the source code, black box
testing looks at how the application functions. It analyzes a working version or final release of the
Web application. This means that the Web application must be deployed and connected with any
components with which it will be interacting. Examples include the Web server, a backend
database, outside modules or widgets, the file directory system of the Operating System and any
other items. However the black box testing tools does not need to know anything about the
underlying system; it only has to be able to interact with the Web application.
Since it is looking at a deployed version of the application, black box testing can analyze the
interaction between the different components and detect vulnerabilities not wholly embedded
within the application. Can an exploit within the application enable a user to access the database,
OS or other component? Does the Web server provide access to pages the application considers
otherwise protected? Can a minor issue with the Web application cause the database to be
corrupted or fail?
Black box testing is optimal for looking at the entire functioning Web application and detecting
security concerns. It focuses on the externally visible behavior of a running Web application. The
application can be an application currently in development or a legacy application which has not
been updated in the recent past.
Black box testing tools have the following benefits:
- Analyze an entire deployed Web application.
Black box testing can analyze an entire Web application as it is deployed with all its
components. If vulnerability is present in the way two components interact with each, black
box testing can detect it.
- Provide development feedback via testing on a staging server.
By integrating black box testing as part of the software development lifecycle, regular and
early feedback can be provided to development. This will help catch any security concerns
before they get to the deployment stage.
- Prevent the gathering of additional "hacking information."
Black box testing implements many of its detection techniques by looking at results from
unexpected input. By looking at the error messages displayed for abnormal data or watching
how the Web application interacts, hackers can gain information about how the application is
deployed. This in turn aids their ability to effectively hack the application. Black box testing
can effectively prevent this from happening.
In the recent past, source code scanning competed with automated black box assessments.
Today, most organizations recognize the need to use both. White box testing is used to capture
some security concerns early and to enforce proper coding techniques; black box testing to is
used to analyze the application throughout the build, test and staging phases.
White Box vs. Black Box Technologies: A Comparison
Today, enterprise class deployments of Web application security technologies are gaining
momentum, but there is still a tendency to view white box technologies and black box Web
application technologies as solving the same problem from different angles. Until the enterprise
market matures, the two technologies are likely to continue to be seen as complementary of one
another, or trade-offs. In reality they solve two entirely different problems.
Where Web applications are concerned, black box technologies offer superior benefits in terms of
finding and assisting in the remediation of the most severe vulnerabilities. More importantly, black
box technologies are the only viable choice for assessing the security of deployed applications
(whether deployed in production or within a test environment).
The graph below shows the real relationship between application vulnerability assessment
solutions (Black Box) and automated white box security solutions in terms of the OWASP Top 10.
This graph makes a general comparison of black box testing solutions (application vulnerability
assessment) to a white box testing tools.
Within the graph above the scores mean the following:
- 0 - 2 means the vulnerability can not be directly detected or the vulnerability detection capability
may be present, but is highly unreliable. Typically associated with high false positives and high
false negatives. The process of detection is similar to guessing based on incomplete evidence.
- 2 - 4 represents a basic ability to detect vulnerability, but only in very limited cases. Prone to a high
percentage of false positives and extremely high false negatives.
- 5 represents the ability to reliably detect vulnerability but in general cases. Prone to some
percentage of false positives and a high percentage false negatives
- 6- 10 represents the ability to detect multiple variations of a vulnerability under a broad range of
conditions. Prone to a low percentage of false positives and a low percentage of false negatives.
Here is a further examination of the pros and cons associated with each.
White Box Testing
Applicable stages: Development, Integration
- can find certain vulnerabilities early in the development of the application
- can point to a specific line of code
- prone to false positives
- development resource consuming
- does not simulate a real world attack
- not effective for finding “real” vulnerabilities; only showing possible ones
- complex implementation
Black Box Testing
Applicable stages: Development, Integration, Deployment, Operations
- simulates real world attacks
- can be performed quickly and automatically
- assessments may be repurposed from stage to stage of the process
- requires compiled executable
- tests only visible interfaces
White Box Testing: The Reality
There are limitations in what White Box Testing Tools (source code analysis tools) can really do.
Below is a summary of their limitations.
- They do not protect against the latest threats.
One of the greatest weaknesses of white box solutions is that they are typically not updated
with the latest security vulnerabilities. Programmers may catch security flaws in their code,
but other vulnerabilities are invisible because the source code analyzer does not have
patterns for those vulnerabilities. An organization that relies on a source code analyzer as its
only means of finding Web application vulnerabilities will face major risk.
- They are not suited for use against large, complex, or heterogeneous applications.
Many applications are only one piece of a broader application framework. Source code
analysis provides a limited picture of the overall security of the application. Source code
analysis tools are blind to the logical workflow of the application as a whole and are quite
often incompatible with the various platform and source code types involved within the
- They do not test application inputs or test input validation.
Source code analysis tools do not test for input validation flaws, because they analyze code
and not application inputs. Since the mechanisms of reading, processing, and handling input
are not interactively tested, limitations or design flaws within input validation schemes will be
invisible to the tool. The majority of the most severe application threats come from bypassing
input validation filters to perform SQL Injection and Script Injection Attacks (XSS). Source
code analysis tools are very limited in their ability to detect these vulnerabilities since they
have no ability to attempt to bypass defenses by actively attacking an input filter or parser.
- Cannot detect design, integration, or architecture flaws.
Web applications are often designed with complex middleware and implicitly trust these
environments to sanitize input and process session data securely. Yet, application code may
contain vulnerabilities through lack of key security protections that are assumed to exist
elsewhere. Commonly an application trusts input from a component of a server or application
framework. These assumptions can result in vulnerabilities because of mistaken trust in the
security of external components that cannot be scanned with white box technologies.
Additionally, development environments like PHP, or other environments, may have their own
vulnerabilities that are transferred to the application. Commercial frameworks and platforms,
(for example, Macromedia Cold Fusion) contain insecure default configurations and
components that are vulnerable to attack when integrated into a custom application. Source
code analysis tools cannot detect the improper implementation of such components, or their
flawed default configuration.
For example, a financial services company has a Web application used to store and export
the preferences of a Web user as their workflow crosses multiple Web applications. That
preference tracking application has components resident on 20 different Web servers, of
different types and version, each Web server running different kinds of middleware. A
functional application-layer script ties those servers together: perl, PHP, Java, and Ruby.
Aside from the different scripting mechanisms, the application itself is written in five different
languages. This presents an intractable problem for source code analysis tools.
It is important for organizations to realize they cannot rely on white box testing tools as a
means for securing their Web applications. Organizations that rely solely on white box
technologies will be exposed to vulnerabilities in their application portfolio. White Box scanner
technologies have a use but the real value they hold for really securing Web applications is
limited at best. Again, the challenges of architecture, API usage, and integration prevent
white box testing tools from having a direct impact on the overall security of an application.
They can neither test in run time nor deal with production applications. White box testing tools
have their use in finding faulty code and can show the possibility of vulnerability.
The Ultimate Question
So, what should an organization do? How should you start testing and securing your
applications. There are three different ways to approach this:
- If you have in-house experts on application security, and have enough budget, purchase
both black box and white box testing solutions. Cenzic offers an integration of its black
box testing solution suite Hailstorm with the best source code solutions in the industry;
- If you have in-house experts but don’t have enough budget, start with purchasing the
black box testing solution. It’ll give you the biggest bang for the buck with much wider
coverage through out the Software Development Lifecycle
- If you don’t have in-house experts, start with using a managed service. For example,
Cenzic ClickToSecure service tests your Web applications remotely, provides you
detailed results and walk thru with Cenzic security experts. No software or hardware
required. Once you are ready to move everything in-house, all the data is migrated
instantly with the product.
Cenzic provides automatic black box testing solutions that quickly and accurately find more
"real" application vulnerabilities in both legacy Web 1.0 and Web 2.0 applications. Cenzic
provides companies a security solution from remote, Software as Service (ClickToSecure®),
for testing one or more applications, to a full enterprise-wide solution (Cenzic Hailstorm®
Enterprise ARC) for effectively managing application security risks across an enterprise.
Cenzic solutions are the most accurate, comprehensive, and extensible in the industry
empowering organizations to stay on top of today’s unrelenting application security threats.
Contact Cenzic email@example.com or 1-866-4-CENZIC.
- Executive Summary
- White and Black Box Testing in the Software Development Lifecycle
- White Box Testing: An Overview
- Black Box Testing: An Overview
- White Box vs. Black Box Technologies: A Comparison
- The Ultimate Question
- Cenzic, Inc.