Applications make the world go round.
Or isn’t that the saying?
In any case,
hardly a day passes
without us using some sort of software application.
This is why software security is essential.
When an application is proven to be insecure,
all hell breaks loose.

There are different kinds of security tests in the market.
This is due to the fact
that what the end user sees is just one part of the application,
which can be analyzed from different points of view.

In this blog post,
we will define the three most popular methods used
in software security testing:
static application security testing (SAST),
software composition analysis (SCA)
and dynamic application security testing (DAST).
We will see their differences
and talk about how they complement each other.
Further,
we also argue that they reach their peak potential
when performed by automated security testing tools
and manually by human experts.

What’s the difference between SAST, SCA and DAST?

SAST and SCA appear coupled in searches,
possibly given that they are both performed
looking at the inner contents of the static application
and not from the outside
while the application is running.
Further,
DAST and SAST are often pitted against each other.
The difference in names (i.e., “dynamic,” “static”)
usually inspires the question
“Which one is better?”
However,
as we will try to convey throughout this post,
these methods are performed with different intentions.
Therefore any one of them is not necessarily better than the other two.
Let’s take a look at each of them separately
to allow you to see our point.

What is SAST?

Static application security testing (SAST)
is a kind of white-box testing.
This means
that security analysts
and tools performing this method have access to source code,
byte code or the application’s binaries.
When people talk about a SAST tool,
they mean a program
that automatically finds errors in code
using sophisticated functions
(e.g., data flow analysis,
control flow analysis,
pattern recognition).
It can find them because they coincide with known errors
it has stored in a database.

It is not a secret
that commercial static application security testing tools generate reports
that contain high rates of false positives.
This is why human verification is always needed.
Experts are responsible for reviewing the results
to determine if they are real issues.
So,
the deployment of SAST tools should be done
along with manual work.
Manual SAST is done
by security testers who understand the application’s context
and find security issues in source code
that the tool could not flag
(i.e., false negatives).
A previous blog post
explains a little more thoroughly
what stages it goes through.
The experts are up to date
in regards to vulnerabilities
thanks to their daily work
and contact with resources
such as the Open Web Application Security Project (OWASP)
and the Common Weakness Ennumeration (CWE).
The combination of continuous automatic
and manual security testing
generates more accurate results.

Why is SAST important?

It’s very important to look at the source code
performing SAST manually alongside automated security testing tools.
To give you an idea,
our 2022 State of Attacks
shows
that “Non-encrypted confidential information”
and “Sensitive information in source code”
are among the top five types of vulnerabilities
causing the most risk exposure
to the systems Fluid Attacks assessed during 2021.

What are the benefits of SAST?

The following are some of the most notable benefits
of static application security testing:

• It can be done continuously,
  early
  and throughout the entire software development lifecycle (SDLC).

• It allows you to know the exact location of a vulnerability,
  like the name of the file and line number.

• As this method informs you of vulnerabilities
  shortly after they have been written,
  remediation can take place just as promptly.

• The earlier you remediate,
  the more you save on economic costs.

• When done manually in combination with SAST tools,
  it yields results with low rates of false positives and false negatives.

What is SCA?

Software composition analysis (SCA)
allows you to inventory your open-source components.
By knowing their versions,
you can check which ones are up to date.
And by knowing the component licenses,
you can change to other components
that do similar stuff
but have licenses compatible with your organization’s policies
in order to prevent legal risk.
Further,
both manually and aided by SCA tools,
this method points at those components
that have vulnerabilities
that are listed in public databases
or have been disclosed by security testers,
researchers
or vendors themselves.

Why is SCA important?

Identifying the risk
related to vulnerable open-source software dependencies
is a top priority.
You heard about Log4Shell.
How could you not?
It is a hot mess to this day.
Threat actors keep exploiting vulnerabilities in Log4j
because a myriad
(perhaps millions, but who knows?)
of applications use it for logging.
It is still making headlines
as people fail to recognize
they use it in their software
and are therefore exposed
to remote code execution and malware attacks,
among others.

Log4j is just one of our problems.
Our 2022 State of Attacks
shows
that “Use of software with known vulnerabilities”
is the type of vulnerability
that generated the most risk exposure
and was also present in most systems
Fluid Attacks assessed during 2021.

Don’t get us wrong, though.
We don’t think open-source is bad.
In fact,
we encourage openly sharing your source code,
as long as you make sure to test it constantly against vulnerabilities.
The importance of open-source security comes,
at least partly,
from the fact that it makes software development easier.
Somewhere around 80%
of code in applications comes from open-source dependencies
and the rest is proprietary code.
The way these libraries are used
to be able to create something new
fits the standard course of the evolution of human culture.
We’ve said it before:
We stand on the shoulders of giants.

What are the benefits of SCA?

The following are among the most remarkable benefits
of software composition analysis:

• It can be done continuously,
  early
  and throughout the entire SDLC.

• It allows you to produce a software bill of materials
  (SBOM; i.e., a document
  that states which software dependencies you’re using).

• It helps identify software supply chain risk
  determined by component quality factors
  like license, version and vulnerabilities.

• When done manually in combination with SCA tools,
  it yields results with low rates of false positives and false negatives.

What is DAST?

Dynamic application security testing (DAST)
is a method to assess running applications.
That is,
these applications are already on a web server,
a virtual machine
or a container and working.
Contrary to SAST, DAST does not require access to the source code
but rather assesses the application’s behavior
from the user side,
so to speak.
As it’s done without seeing the source code,
it’s a type of black-box testing.

Dynamic application security testing involves sending attack vectors
(e.g., strings of code)
to application endpoints to inspect unexpected behavior.
So,
for example,
if an application does not properly discard unsafe inputs,
it is vulnerable to injection attacks
(e.g., SQL injection).
These attacks may allow criminals
to obtain confidential information
or achieve remote code execution.
So,
DAST can help identify these kinds of risks
long before the application is even in the hands of end users.

A limitation of dynamic application security testing is
that it cannot point
to where exactly vulnerabilities reside in source code.
Further,
as a shared limitation
with static application security testing
and software composition analysis,
when done with tools only,
it may produce reports with high rates of false positives
and miss actual vulnerabilities.
But the way to overcome false positives
and false negatives
is combining the use of DAST tools with manual work.
When DAST is done manually,
the attack surface may be more accurately defined,
and the attacks may be specially crafted
and up to date on the techniques used by threat actors.

Why is DAST important?

We frequently publish advisories
of software vulnerable to cross-site scripting,
cross-site request forgery
and injection,
among other security issues.
As our research team can attest,
an attacker need not have access to the source code
to learn how to cause a great damage.
They need only probe applications
trying out creative ways to get unauthorized access.
This is why DAST should be conducted constantly.
By proactively attacking their own application from the outside,
organizations can find issues before criminals do.
Then developers can fix the application from the inside,
effectively reducing risks.

What are the benefits of DAST?

Some of the most notable benefits
of dynamic application security testing are the following:

• It can be done continuously,
  early
  and throughout the entire SDLC.

• It helps identify vulnerabilities
  that are caused by the interaction with the application.

• It allows you to simulate attacks by malicious hackers.

• When done manually in combination with DAST tools,
  the attacks can be custom made and more clever,
  yielding results with low rates of false positives
  and false negatives.

SAST vs SCA vs DAST?

After all these definitions,
what could be said about the validity
of common comparisons like SAST vs SCA
and SAST vs DAST?
Which one is best?
It’s plain to see
that SAST, DAST and SCA are executed with different scopes
within the same object of assessment.
They each benefit software security in their own way
and offer their own advantages.
So,
if you ask us
whether any one of these methods is better than the other two,
we will respond with another question,
“What are you intending to do?”

If your answer is something to the effect of
“I just wanna know which one will secure my software more effectively,”
we urge you to snap out of it
and think of the importance of comprehensive testing instead.
That is,
you need to get rid of vulnerabilities in source code,
manage your open-source risk
and test the application from the stance of an attacker
continuously.

Combining SAST, SCA and DAST for comprehensive testing

When you adopt a combined approach to security testing,
you are broadening your scope,
having a better chance
of identifying risk exposure more accurately.
Moreover,
we urge you to apply SAST, DAST and SCA continuously across the SDLC,
introduce them as soon as possible
and combine the manual work with automated testing through it all.
The idea is to maintain a strong remediation practice
throughout development
in which every vulnerability is detected and addressed promptly.
The adoption of comprehensive testing will prove to be helpful
in building a DevSecOps culture
in your organization.

Enjoy Fluid Attacks’ comprehensive security testing

At Fluid Attacks,
we offer SAST,
SCA
and DAST
throughout the entire SDLC,
all in a single solution:
Continuous Hacking.
Our highly certified
ethical hackers
work continuously alongside security testing tools
to detect all the vulnerabilities in the assessed systems.
We are constantly expanding the types of vulnerabilities
that the tools are able to detect,
generating exhaustive reports
with minimal false positive rates
and boosting our experts’ efficiency.
In the process,
we help you comply with several security standards
and reduce remediation costs
by up to 90%.

Click here
to learn about the 21-day free trial
of our Continuous Hacking Machine Plan,
which lets you try our automated security testing,
or ask us now about our Squad Plan
to add ethical hackers to the mix.
To learn more,
contact us!

*** This is a Security Bloggers Network syndicated blog from Fluid Attacks RSS Feed authored by Jason Chavarría. Read the original post at: https://fluidattacks.com/blog/differences-between-sast-sca-dast/