How to Use the Command 'debsecan' (with Examples)

Debsecan, or Debian Security Analyzer, is a tool designed to help maintain the security of a Debian-based system by listing potential vulnerabilities in the installed packages. By scanning the system, debsecan identifies outdated software that could potentially be exposed to security exploits, enabling system administrators and users to take swift action in mitigating these risks. Debsecan is particularly valuable for ensuring systems remain secure by proactively identifying and addressing vulnerabilities within Debian installations.

Use case 1: List Vulnerable Installed Packages on the Current Host

Code:

debsecan

Motivation:

The primary motivation for using this command is to obtain a comprehensive list of all known security vulnerabilities present in the packages installed on the current system. This helps system administrators quickly assess the security posture of their installation and determine which packages might require urgent updates or replacements.

Explanation:

• debsecan: This is the command used to invoke the Debian Security Analyzer. When run without any additional options, debsecan simply scans the system’s installed packages and lists those that are currently tested and identified as vulnerable.

Example Output:

CVE-2022-1234: package-name (severity: high)
CVE-2023-5678: another-package (severity: low)

Use case 2: List Vulnerable Installed Packages of a Specific Suite

Code:

debsecan --suite release_code_name

Motivation:

A Debian system can run packages from different suites or releases (such as stable, testing, or unstable). It’s critical to be able to target a specific suite to verify whether its packages have known vulnerabilities, especially in environments where systems are upgraded progressively across different releases.

Explanation:

• --suite release_code_name: This option allows users to specify the Debian suite they are interested in examining. By specifying a release code name (such as ‘buster’, ‘bullseye’, etc.), the user can hone in specifically on packages from that suite, providing a tailored security assessment.

Example Output:

CVE-2022-1234: package-name from 'buster' (severity: high)
CVE-2023-5678: another-package from 'buster' (severity: medium)

Use case 3: List Only Fixed Vulnerabilities

Code:

debsecan --suite release_code_name --only-fixed

Motivation:

Sometimes, system administrators prefer to focus only on those vulnerabilities that have been addressed by the Debian security team (i.e., “fixed vulnerabilities”). This helps in efficiently allocating resources to apply only those updates that have confirmed fixes available.

Explanation:

• --suite release_code_name: Targets a specific suite as mentioned above.
• --only-fixed: This option restricts the output to only show vulnerabilities for which fixes have been issued. This is particularly useful to ensure immediate attention to packages that can be immediately updated to rectify vulnerabilities.

Example Output:

Fixed CVE-2022-1234: package-name (severity: high)

Use case 4: List Only Fixed Vulnerabilities of Unstable (“sid”) and Mail to Root

Code:

debsecan --suite sid --only-fixed --format report --mailto root --update-history

Motivation:

In environments running the unstable “sid” suite, it is imperative that security vulnerabilities are tracked consistently due to the rapidly changing nature of the suite. This command not only generates a report of fixed vulnerabilities but also automates notification to the root user of the system, facilitating quicker interventions.

Explanation:

• --suite sid: Specifies that the unstable suite should be analyzed.
• --only-fixed: Only lists vulnerabilities that have fixes available.
• --format report: Outputs the results in a report format, which is structured and detailed.
• --mailto root: Sends an email containing the report to the root user, ensuring that the individual responsible for system maintenance is promptly informed.
• --update-history: Keeps track of changed vulnerabilities over time, supplementing the report with trends that are useful for audits and compliance purposes.

Example Output:

--- Email Sent to root ---
Subject: Security Report for SID
Body:
Fixed CVE-2022-1234: package-example (severity: critical)

Use case 5: Upgrade Vulnerable Installed Packages

Code:

sudo apt upgrade $(debsecan --only-fixed --format packages)

Motivation:

Once vulnerabilities are identified and fixes are available, one of the most effective mitigations is upgrading the vulnerable packages. This command automates the upgrade process by integrating debsecan’s output with the apt package manager, streamlining the remediation process.

Explanation:

• sudo: Run the command with elevated privileges, required for package upgrades.
• apt upgrade: The package management command in Debian used to install updates.
• $(debsecan --only-fixed --format packages): This part of the command fetches a list of packages with known vulnerabilities that have been fixed, formatted properly to be directly consumed by the apt command, thus ensuring only those packages are upgraded.

Example Output:

Reading package lists... Done
Building dependency tree
Reading state information... Done
Calculating upgrade... Done
The following packages will be upgraded:
  package-name another-package
...

Conclusion:

Debsecan is an important tool for maintaining the security of Debian-based systems. With the examples provided, users can effectively monitor known vulnerabilities and take necessary actions to secure their system promptly. By integrating with other command-line utilities like apt and email, debsecan provides a comprehensive and automated approach to vulnerability management.