Why Repojacking Is a New Mega Threat & Protecting Your Projects

Repojacking, a term that might be unfamiliar to some, is a malicious activity where cybercriminals manipulate or control a code repository to serve their nefarious purposes.

July 16, 2023

What Is Repojacking? 

Repojacking, a term that might be unfamiliar to some, is a malicious activity where cybercriminals manipulate or control a code repository to serve their nefarious purposes. It’s a form of cyberattack that has recently gained prominence due to the increasing reliance on open-source repositories in the software development industry. By hijacking these repositories, cybercriminals can inject malicious codes, exploit vulnerabilities, or even steal sensitive data.

The threat of repojacking is particularly severe given the collaborative nature of open-source repositories. These platforms, such as GitHub, GitLab, or Bitbucket, often host projects where numerous developers worldwide contribute. While this collaboration fosters innovation and facilitates rapid software development, it also opens up potential vulnerabilities. If a cybercriminal successfully repojacks a popular open-source project, they could potentially affect thousands, if not millions, of users.

As more and more organizations turn to open-source software to power their digital infrastructure, it’s crucial to understand repojacking and its potential repercussions. A single compromised repository can lead to severe security breaches, potentially leading to significant financial and reputational damage. Hence, understanding repojacking is not just necessary for software developers but also for organizations that rely on open-source software.

In this article:

How Do Repojacking Attacks Work? 

Repojacking attacks usually begin with the perpetrator gaining unauthorized access to a code repository. This could be through brute force attacks, where the attacker continuously tries various username and password combinations until they find a match, or more sophisticated methods such as phishing or social engineering. Once inside, the attacker can manipulate the codebase to serve their purposes.

One of the most common ways repojacking attacks are carried out is by injecting malicious code into the repository. This could be a hidden backdoor that allows the attacker continuous access to the system, a piece of malware that infects the end users’ machines, or even a ransomware that encrypts the users’ data and demands a ransom for its release. The injected code is often carefully concealed to avoid detection, making it challenging to identify and eliminate.

Another, less common method of repojacking involves exploiting vulnerabilities in code powering the repository itself. If the repository’s developers have not adequately secured their code, an attacker can exploit these vulnerabilities to gain unauthorized access or control. For example, an attacker could exploit a buffer overflow vulnerability to execute arbitrary code or a SQL injection flaw to manipulate the repository’s database. These attacks can have severe consequences, potentially leading to data breaches or system failures.

The Impact of Repojacking 

The impact of repojacking can be devastating. For software developers, a repojacked repository means a loss of control over their project. They may have to spend significant time and resources to identify and eliminate the threat, potentially delaying the project’s progress. Additionally, their reputation could be damaged if users or contributors discover that their repository has been compromised.

For end users of the software developed from the repojacked repository, the consequences can be even more severe. If the attacker has injected malicious code into the repository, the users’ systems could be infected with malware or ransomware. They could potentially lose access to their data or even have their personal information stolen. In worst-case scenarios, a repojacked repository can be used as a launchpad for widespread cyberattacks.

Organizations that rely on open-source software are also at risk. A single repojacked repository in their digital infrastructure can lead to significant security breaches. These breaches can result in substantial financial losses, not to mention the potential reputational damage. Furthermore, if the repo is owned by an organization, it may find itself in violation of industry standards or regulations, leading to fines and legal complications.

How To Protect Your Projects Against Repojacking

1. Avoid Direct Links to GitHub

Never consider GitHub repositories as a replacement for a package manager. GitHub repositories do not guarantee persistence; linked addresses can change over time so they are not reliable for direct code dependencies. Using a dedicated package manager is far superior as it offers optimal usability and security. 

Even if you avoid linking to GitHub, keep in mind that repojacking may still be a potential threat if the dependencies you use link directly to a GitHub URL. Even if you scrutinize your transitive dependencies for direct links, there could still be a covert dependency to a GitHub repo. This is often observed with build scripts that fetch code directly from a developer’s repository or within test code.

2. Use Version Pinning

Version pinning means specifying a certain version of a dependency which is then added to the project, guaranteeing that only that specific version gets downloaded. In the context of GitHub link dependencies, this usually takes the shape of a SHA1 git commit hash, included to direct your package manager to download a specific commit from a git repository. This ensures that even if the repository is compromised, an attacker would find it challenging to alter the code without also modifying the commit hash. 

Version pinning can also be used to bind a dependency to a particular branch or tag, however, these do not offer absolute security as a hacker could potentially update those branches or tags.

3. Use Lock Files

A lock file is a document generated by your package manager which contains a listing of precisely pinned dependencies. This guarantees that future project builds will download exactly the same package and version as defined in the lock file. Additionally, lock files can sometimes include an integrity hash that further attests to the authenticity of the downloaded package.

4. Download All Dependencies in Advance

A good way to prevent repojacking is to download all dependencies beforehand and integrate them into your repository. This ensures that your repositories are self-contained with all the necessary code. Because all your dependencies are pre-loaded, it is akin to a lock file that includes the content for your dependencies. 

This way, even if a dependency gets compromised, you already have the code you need. However, this does not completely eliminate the repojacking risk. You might still be exposed the next time you refresh your dependencies, if one of them has been infiltrated.