Downloading .debs from untrusted sources

While packages offer a convenient method to package and distribute software, this ease of distribution inherently comes with risks. As an example, consider a scenario where a user has provided a direct download link for a package on a public forum. Downloading and installing this package from such a source is discouraged for several reasons.

Lack of security verification

Unlike software sourced from Ubuntu’s official repositories (e.g., the Ubuntu Archive), which includes packages vetted by the Ubuntu Security team, a package file originating from an untrusted source, like a public forum, has likely undergone no security screening. This lack of verification means that bad actors may have made modifications to the software contained within the package.

When possible, always source packages from trusted sources and not from untrusted sources like public forums.

Potential for malware

Installing a package to make software available system-wide almost always requires root privileges. If a bad actor has modified a .deb file for malicious reasons, providing root privileges can elevate the risk that malware, ransomware, spyware, or keyloggers are installed on your system.

Whenever running a command with root privileges, always ensure you know what the command is going to do, and that the inputs you are passing come from trusted sources.

System instability and dependency issues

Software retrieved from trusted sources, such as the Ubuntu Archive, has been built and tested to work seamlessly with other packages that may already be present on a given system. In contrast, a package from an unknown or untrusted source might have been built for a different version of Ubuntu or have conflicting dependencies. The installation of such a .deb can cause system instability due to these conflicts, which in the worst case can render a system unusable.

To avoid dependency issues and to ensure system stability, it is always best to retrieve and install packages from trusted sources, like Ubuntu’s official repositories.