Historically, cybercriminals are as lazy as they are innovative. They can come up with clever exploits and attack vectors, but they still generally focus on the low-hanging fruit in the most target-rich environments. Recently, attackers seem to have shifted focus away from directly targeting companies with strong security or a wealth of resources, instead going after weak links in the software supply chain.
No matter how many resources or how much effort you dedicate to securing your networks and protecting your data, it can all be for nothing if you trust a third-party supplier or vendor that is vulnerable. It is also true of your software supply chain, because the process of developing and deploying software offers opportunities that attackers can exploit.
The Case of Xcode Ghost
iOS devices are considered to be exceptionally secure. iOS is not impervious to attack or exploit, but it is more secure than the competing Android platform. Apps for iOS are also considered to be more secure, because Apple’s App Store is a “walled garden” with a stringent review process for an app to be approved.
A few years ago, however, it was discovered that more than 4,000 apps in the Apple App Store contained malicious code. Attackers had figured out how to leverage a weakness in the software supply chain to get past the gatekeepers of the walled garden.
How did they do it? iOS apps have to be written in Xcode. The Xcode software is provided for free, but the Apple servers are often slow—especially when trying to download from China, so developers often just search the web to get Xcode from a third-party site. Cybercriminals developed a malicious version of Xcode, then gamed the systems to ensure their version of the software would show up at the top of online searches.
Apps developed with the malicious Xcode software contained extra code that would phone home and provide the attacker a backdoor—and an opportunity to inject malicious code or execute commands within the compromised apps.
The Xcode Ghost incident is an excellent example of a software supply chain attack, and a perfect illustration of attackers going after the low-hanging fruit. iOS is relatively secure. The Apple App Store is protected and apps are reviewed to ensure they meet strict criteria. So, instead of trying to go after Apple or iOS, attackers figured out how to strike the platform used to develop the apps and sneak in through the back door.
I spoke with Ryan Olson, Intelligence Director for Palo Alto Networks, about the rising threat of attacks on the software supply chain. He explained that attackers know that when they are going after a hard target that would be difficult to defeat directly, there is a better and easier way: Just figure out who they trust and go after the low-hanging fruit.
This becomes a potentially larger issue in the context of DevOps and automation. The recent NotPetya ransomware was propagated through a malicious update. If your systems or software are configured to update and/or deploy automatically, a software supply chain attack can be in the wild and compromising your applications or data before you know it.
There are tools available to scan images, applications or containers before deploying them, but they typically test for known vulnerabilities or overt crashes or conflicts. They are not designed to look for latent backdoors that might be buried in the code.
Olson recommends that you start taking a closer look at the software vendors you rely on. It is important to understand how they are securing and protecting their code—because their weaknesses expose you to threats by virtue of the trust you give them and their apps.