In this lesson, we're going to explore
image and artifact tampering
and how they can be significant attack vectors
in penetration testing.
Image and artifact tampering
involves manipulating virtual machine images,
container images, and software artifacts
to introduce vulnerabilities or malicious code.
Let's start by breaking down
what do we mean by images and artifacts
when it comes down to cloud computing?
Think of images as blueprints for building a house.
When it comes to IT, these blueprints are used
to create virtual machines or containers.
Artifacts, on the other hand,
are the building blocks like bricks and windows,
which, in our case, are software components
and dependencies which are used to build
and deploy applications.
If these blueprints or building blocks are tampered with,
the resulting structure can have hidden weaknesses
and malicious functionalities.
Imagine you're working in a cloud environment
where your virtual machine (VM) images
are used to deploy servers.
These images contain the operating system applications
and configurations needed to run a VM.
If an attacker gains access to these images,
they can insert malicious code or backdoors.
For example, they might install a rootkit
that gives them persistent access
to any VM created from the image.
During a penetration test,
you examine the integrity of VM images
to ensure that they haven't been tampered with.
Consider a scenario where an organization
uses a shared repository for storing VM images.
If this repository isn't properly secured,
an attacker could replace a legitimate image
with a tampered one.
When the organization deploys VMs from this image,
they inadvertently introduce vulnerabilities
into their environment.
As a pentester, we should always verify the source
and integrity of images being used.
Next, let's discuss container images.
Containers are lightweight,
portable, and self-sufficient environments
that include everything needed to run a piece of software.
Container images are stored in registries like DockerHub.
If an attacker can tamper with a container image,
they can introduce vulnerabilities
or malware that will propagate whenever the image is used.
For instance, an attacker might insert
a cryptocurrency miner into a container image.
Once deployed,
the container will use the organization's resources
to mine cryptocurrency for the attacker.
In a pentest, you would again check the integrity
and security of container images
to ensure that they're free from tampering.
In 2019, there was a DockerHub incident
where a popular open source container
was found to be compromised.
Attackers had injected hidden malware
into an official Alpine Linux image,
which was then downloaded by numerous developers
from the public registry.
Once these compromised containers were deployed,
the malware activated,
potentially allowing attackers to execute arbitrary code
or steal sensitive data from the affected systems.
Lastly, let's discuss software artifacts.
Software artifacts such as libraries,
packages and modules are essential components
of modern applications.
These artifacts are often stored in repositories
like npm for JavaScript, PyPI for Python, or Maven for Java.
If an attacker can tamper with these artifacts,
they can introduce vulnerabilities
into the applications that use them.
For instance, an attacker might inject malicious code
into a popular library.
When developers include this library into their projects,
the malicious code gets executed.
During a penetration test,
you review the artifacts being used
and ensure they come from trusted sources
that haven't been tampered with.
For instance, a real world example of this scenario
is the event-stream incident in 2018.
An attacker injected malicious code
into the popular event-stream library,
which is widely used in Node.js projects.
The attacker gained access to the library
by convincing the original maintainer to hand over control,
under the guise of helping with maintenance.
Once in control, the attacker added a new dependency
containing malicious code designed to steal Bitcoin wallets
from specific applications.
When developers included this compromising version
of event-stream into their projects,
the malicious code was executed,
leading to potential theft of sensitive data.
During a penetration test,
you would review the third party libraries
and dependencies used in the target's code base.
This involves checking the integrity
and source of these libraries,
ensuring that they come from trusted sources
and verify they haven't been tampered with.
Tools like npm audit, yarn audit
or similar tools for ecosystems
can help identify known vulnerabilities in dependencies.
Additionally, you would recommend practices
such as maintaining a strict dependency management policy,
regularly updating the libraries
and using tools to monitor for suspicious changes
or vulnerabilities in third party components.
Additionally, an attacker could tamper with these images
in transit or at rest,
introducing vulnerabilities or back doors.
Exploiting image and artifact tampering
can also involve inserting vulnerabilities
that facilitate future attacks.
For instance, adding a weak default password
or disabling security features in a VM image
can make it easier for attackers
to compromise systems later.
In a pentest, you would look for such modifications
that weakened security postures
and demonstrate how they can be exploited.
So remember, image and artifact tampering
can be a significant attack vector.
By understanding and identifying issues
such as tampered VM images, compromised container images,
manipulated software artifacts,
and lack of integrity checks,
you can help organizations protect their environments
from these subtle yet dangerous threats.
Effective pentesting involves scrutinizing the sources
and integrity of images and artifacts,
demonstrating how tampering can introduce vulnerabilities,
and ensuring that robust security measures are in place
to prevent such attacks.