Research

Mike and Rich had a call this week with another prospect who was given some pretty bad cloud advice. We spend a little time trying to figure out why we keep seeing so much bad advice out there (seriously, BIG B BAD not OOPSIE bad). Then we focus on the key things to look for to figure out w Mike and Rich had a call this week with another prospect who was given some pretty bad cloud advice. We spend a little time trying to figure out why we keep seeing so much bad advice out there (seriously, BIG B BAD not OOPSIE bad). Then we focus on the key things to look for to figure out when someone is leading you down the wrong path in your cloud migration. Oh… and for those with sensitive ears, time to engage the explicit flag. Watch or listen: Share:

This post is focused on security testing your code and container, and verifying that both conform to security and operational practices. One of the major advances over the last year or so is the introduction of security features for the software supply chain, from both Docker itself and a handful of third-party vendors. All the solutions focus on slightly different threats to container construction, with Docker providing tools to certify that containers have made it through your process, while third-party tools are focused on vetting the container contents. So Docker provides things like process controls, digital signing services to verify chain of custody, and creation of a Bill of Materials based on known trusted libraries. In contrast, third-party tools to harden container inputs, analyze resource usage, perform static code analysis, analyze the composition of libraries, and check against known malware signatures; they can then perform granular policy-based container delivery based on the results. You will need a combination of both, so we will go into a bit more detail: Container Validation and Security Testing Runtime User Credentials: We could go into great detail here about runtime user credentials, but will focus on the most important thing: Don’t run the container processes as root, as that provides attackers access to attack other containers or the Docker engine. If you get that right you’re halfway home for IAM. We recommend using specific user accounts with restricted permissions for each class of container. We do understand that roles and permissions change over time, which requires some work to keep permission maps up to date, but this provides a failsafe when developers change runtime functions and resource usage. Security Unit Tests: Unit tests are a great way to run focused test cases against specific modules of code – typically created as your dev teams find security and other bugs – without needing to build the entire product every time. This can cover things such as XSS and SQLi testing of known attacks against test systems. Additionally, the body of tests grows over time, providing a regression testbed to ensure that vulnerabilities do not creep back in. During our research, we were surprised to learn that many teams run unit security tests from Jenkins. Even though most are moving to microservices, fully supported by containers, they find it easier to run these tests earlier in the cycle. We recommend unit tests somewhere in the build process to help validate the code in containers is secure. Code Analysis: A number of third-party products perform automated binary and white box testing, failing the build if critical issues are discovered. We recommend you implement code scans to determine if the code you build into a container is secure. Many newer tools have full RESTful API integration within the software delivery pipeline. These tests usually take a bit longer to run, but still fit within a CI/CD deployment framework. Composition Analysis: A useful technique is to check library and supporting code against the CVE (Common Vulnerabilities and Exposures) database to determine whether you are using vulnerable code. Docker and a number of third parties provide tools for checking common libraries against the CVE database, and they can be integrated into your build pipeline. Developers are not typically security experts, and new vulnerabilities are discovered in common tools weekly, so an independent checker to validate components of your container stack is essential. Resource Usage Analysis: What resources does the container use? What external systems and utilities does it depend upon? To manage the scope of what containers can access, third-party tools can monitor runtime access to environment resources both inside and outside the container. Basically, usage analysis is an automated review of resource requirements. These metrics are helpful in a number of ways – especially for firms moving from a monolithic to a microservices architecture. Stated another way, this helps developers understand what references they can remove from their code, and helps Operations narrow down roles and access privileges. Hardening: Over and above making sure what you use is free of known vulnerabilities, there are other tricks for securing applications before deployment. One is to check the contents of the container and remove items that are unused or unnecessary, reducing attack surface. Don’t leave hard-coded passwords, keys, or other sensitive items in the container – even though this makes things easy for you, it makes them much easier for attackers. Some firms use manual scans for this, while others leverage tools to automate scanning. App Signing and Chain of Custody: As mentioned earlier, automated builds include many steps and small tests, each of which validates that some action was taken to prove code or container security. You want to ensure that the entire process was followed, and that somewhere along the way some well-intentioned developer did not subvert the process by sending along untested code. Docker now provides the means to sign code segments at different phases of the development process, and tools to validate the signature chain. While the code should be checked prior to being placed into a registry or container library, the work of signing images and containers happens during build. You will need to create specific keys for each phase of the build, sign code snippets on test completion but before the code is sent onto the next step in the process, and – most importantly – keep these keys secured so an attacker cannot create their own code signature. This gives you some guarantee that the vetting process proceeded as intended. Share:

I have received some great feedback on my post last week on bastion accounts and networks. Mostly that I left some gaps in my explanation which legitimately confused people. Plus, I forgot to include any pretty pictures. Let’s work through things a bit more. First, I tended to mix up bastion accounts and networks, often saying “account/networks”. This was a feeble attempt to discuss something I mostly implement in Amazon Web Services that can also apply to other providers. In Amazon an account is basically an AWS subscription. You sign up for an account, and you get access to everything in AWS. If you sign up for a second account, all that is fully segregated from every other customer in Amazon. Right now (and I think this will change in a matter of weeks) Amazon has no concept of master and sub accounts: each account is totally isolated unless you use some special cross-account features to connect parts of accounts together. For customers with multiple accounts AWS has a mechanism called consolidated billing that rolls up all your charges into a single account, but that account has no rights to affect other accounts. It pays the bills, but can’t set any rules or even see what’s going on. It’s like having kids in college. You’re just a checkbook and an invisible texter. If you, like Securosis, use multiple accounts, then they are totally segregated and isolated. It’s the same mechanism that prevents any random AWS customer from seeing anything in your account. This is very good segregation. There is no way for a security issue in one account to affect another, unless you deliberately open up connections between them. I love this as a security control: an account is like an isolated data center. If an attacker gets in, he or she can’t get at your other data centers. There is no cost to create a new account, and you only pay for the resources you use. So it makes a lot of sense to have different accounts for different applications and projects. Free (virtual) data centers for everyone!!! This is especially important because of cloud metastructure. All the management stuff like web consoles and APIs that enables you to do things like create and destroy entire class B networks with a couple API calls. If you lump everything into a single account, more administrators (and other power users) need more access, and they all have more power to disrupt more projects. This is compartmentalization and segregation of duties 101, but we have never before had viable options for breaking everything into isolated data centers. And from an operational standpoint, the more you move into DevOps and PaaS, the harder it is to have everyone running in one account (or a few) without stepping on each other. These are the fundamentals of my blast radius post. One problem comes up when customers need a direct connection from their traditional data center to the cloud provider. I may be all rah rah cloud awesome, but practically speaking there are many reasons you might need to connect back home. Managing this for multiple accounts is hard, but more importantly you can run into hard limits due to routing and networking issues. That’s where a bastion account and network comes in. You designate an account for your Direct Connect. Then you peer into that account (in AWS using cross-account VPC peering support) any other accounts that need data center access. I have been saying “bastion account/network” because in AWS this is a dedicated account with its own dedicated VPC (virtual network) for the connection. Azure and Google use different structures, so it might be a dedicated virtual network within a larger account, but still isolated to a subscription, or sub-account, or whatever mechanism they support to segregate projects. This means: Not all your accounts need this access, so you can focus on the ones which do. You can tightly lock down the network configuration and limit the number of administrators who can change it. Those peering connections rely on routing tables, and you can better isolate what each peered account or network can access. One big Direct Connect essentially “flattens” the connection into your cloud network. This means anyone in the data center can route into and attack your applications in the cloud. The bastion structure provides multiple opportunities to better restrict network access to destination accounts. It is a way to protect your cloud(s) from your data center. A compromise in one peered account cannot affect another account. AWS networking does not allow two accounts peered to the same account to talk to each other. So each project is better isolated and protected, even without firewall rules. For example the administrator of a project can have full control over their account and usage of AWS services, without compromising the integrity of the connection back to the data center, which they cannot affect – they only have access to the network paths they were provided. Their project is safe, even if another project in the same organization is totally compromised. Hopefully this helps clear things up. Multiple accounts and peering is a powerful concept and security control. Bastion networks extend that capability to hybrid clouds. If my embed works, below you can see what it looks like (a VPC is a virtual network, and you can have multiple VPCs in a single account). Share:

This post will focus on the ‘runtime’ aspects of container security. Unlike the tools and processes discussed in previous sections, here we will focus on containers in production systems. This includes which images are moved into production repositories, security around selecting and running containers, and the security of the underlying host systems. Runtime Security The Control Plane: Our first order of business is ensuring the security of the control plane – the platforms for managing host operating systems, the scheduler, the container engine(s), the repository, and any additional deployment tools. Again, as we advised for build environment security, we recommend limiting access to specific administrative accounts: one with responsibility for operating and orchestrating containers, and another for system administration (including patching and configuration management). We recommend network segregation and physical (for on-premise) or logical segregation (for cloud and virtual) systems. Running the Right Container: We recommend establishing a trusted image repository and ensuring that your production environment can only pull containers from that trusted source. Ad hoc container management is a good way to facilitate bypassing of security controls, so we recommend scripting the process to avoid manual intervention and ensure that the latest certified container is always selected. Second, you will want to check application signatures prior to putting containers into the repository. Trusted repository and registry services can help, by rejecting containers which are not properly signed. Fortunately many options are available, so find one you like. Keep in mind that if you build many containers each day, a manual process will quickly break down. You’ll need to automate the work and enforce security policies in your scripts. Remember, it is okay to have more than one image repository – if you are running across multiple cloud environments, there are advantages to leveraging the native registry in each. Beware the discrepancies between platforms, which can create security gaps. Container Validation and BOM: What’s in the container? What code is running in your production environment? How long ago did we build this container image? These are common questions asked when something goes awry. In case of container compromise, a very practical question is: how many containers are currently running this software bundle? One recommendation – especially for teams which don’t perform much code validation during the build process – is to leverage scanning tools to check pre-built containers for common vulnerabilities, malware, root account usage, bad libraries, and so on. If you keep containers around for weeks or months, it is entirely possible a new vulnerability has since been discovered, and the container is now suspect. Second, we recommend using the Bill of Materials capabilities available in some scanning tools to catalog container contents. This helps you identify other potentially vulnerable containers, and scope remediation efforts. Input Validation: At startup containers accept parameters, configuration files, credentials, JSON, and scripts. In some more aggressive scenarios, ‘agile’ teams shove new code segments into a container as input variables, making existing containers behave in fun new ways. Either through manual review, or leveraging a third-party security tool, you should review container inputs to ensure they meet policy. This can help you prevent someone from forcing a container to misbehave, or simply prevent developers from making dumb mistakes. Container Group Segmentation: Docker does not provide container-level restriction on which containers can communicate with other containers, systems, hosts, IPs, etc. Basic network security is insufficient to prevent one container from attacking another, calling out to a Command and Control botnet, or other malicious behavior. If you are using a cloud services provider you can leverage their security zones and virtual network capabilities to segregate containers and specify what they are allowed to communicate with, over which ports. If you are working on-premise, we recommend you investigate products which enable you to define equivalent security restrictions. In this way each application has an analogue to a security group, which enables you to specify which inbound and outbound ports are accessible to and from which IPs, and can protect containers from unwanted access. Blast Radius: An good option when running containers in cloud services, particularly IaaS clouds, is to run different containers under different cloud user accounts. This limits the resources available to any given container. If a given account or container set is compromised, the same cloud service restrictions which prevent tenants from interfering with each other limit possible damage between accounts and projects. For more information see our post on limiting blast radius with user accounts. Platform Security In Docker’s early years, when people talked about ‘container’ security, they were really talking about how to secure the Linux operating system underneath Docker. Security was more about the platform and traditional OS security measures. If an attacker gained control of the host OS, they could pretty much take control of anything they wanted in containers. The problem was that security of containers, their contents, and even the Docker engine were largely overlooked. This is one reason we focused our research on the things that make containers – and the tools that build them – secure. That said, no discussion of container security can be complete without some mention of OS security. We would be remiss if we did not talk about host/OS/engine security, at least a bit. Here we will cover some of the basics. But we will not go into depth on securing the underlying OS. We could not do that justice within this research, there is already a huge amount of quality documentation available on the operating system of your choice, and there are much more knowledgable sources to address your concerns and questions on OS security. Kernel Hardening: Docker security depends fundamentally on the underlying operating system to limit access between ‘users’ (containers) on the system. This resource isolation model is built atop a virtual map called Namespaces, which maps specific users or group of users to a subset of resources (e.g.: networks, files, IPC, etc.) within their Namespace. Containers should run under a specified user ID. Hardening starts with a secure