xavier / sobelow

Security-focused static analysis for the Phoenix Framework

Sobelow

Sobelow is a security-focused static analysis tool for the Phoenix framework. For security researchers, it is a useful tool for getting a quick view of points-of-interest. For project maintainers, it can be used to prevent introducing a number of common vulnerabilities.

Currently Sobelow detects some types of the following security issues:

• Insecure configuration
• Known-vulnerable Dependencies
• Cross-Site Scripting
• SQL injection
• Command injection
• Denial of Service
• Directory traversal
• Unsafe serialization

Potential vulnerabilities are flagged in different colors according to confidence in their insecurity. High confidence is red, medium confidence is yellow, and low confidence is green.

A finding is typically marked "low confidence" if it looks like a function could be used insecurely, but it cannot reliably be determined if the function accepts user-supplied input. That is to say, green findings are not secure, they just require greater manual validation.

Note: This project is in constant development, and additional vulnerabilities will be flagged as time goes on. If you encounter a bug, or would like to request additional features or security checks, please open an issue!

Installation

To install Sobelow, you must have a working Elixir environment. Then, execute the following from the command line:

$ mix archive.install hex sobelow

You may also install directly from GitHub with the following command:

$ mix archive.install github nccgroup/sobelow

Use

The simplest way to scan a Phoenix project is to run the following from the project root:

$ mix sobelow

Options

• --root -r - Specify application root directory
• --with-code -v - Print vulnerable code snippets
• --ignore -i - Ignore modules
• --ignore-files - Ignore files
• --details -d - Get module details
• --all-details - Get all module details
• --private - Skip update checks
• --router - Specify router location
• --exit - Return non-zero exit status
• --format -f - Specify findings output format
• --quiet - Return no output if there are no findings
• --compact - Minimal, single-line findings

The root option takes a path argument:

$ mix sobelow --root ../my_project

The with-code option takes no arguments:

$ mix sobelow --with-code

The ignore option takes a comma-separated list of modules:

$ mix sobelow -i XSS.Raw,Traversal

The ignore-files option takes a comma-separated list of file names. File names should be absolute paths, or relative to the application root.

$ mix sobelow --ignore-files config/prod.exs

The details option takes a single module:

$ mix sobelow -d Config.CSRF

The exit option accepts a confidence threshold (low, medium, or high), and will return a non-zero exit status at or above that threshold.

$ mix sobelow --exit Low

The format option accepts an output format for findings. Current formats include txt (the default) and json.

Note: The json format option does not support the --with-code flag. All findings are organized by confidence level, and contain a "type" key. However, other keys may vary between finding types.

$ mix sobelow --format json

Configuration Files

Sobelow allows users to save frequently used options in a configuration file. For example, if you find yourself constantly running:

$ mix sobelow -i XSS.Raw,Traversal --with-code --exit Low

You can use the --save-config flag to create your .sobelow-conf config file:

$ mix sobelow -i XSS.Raw,Traversal --with-code --exit Low --save-config

This command will create the .sobelow-conf file at the root of your application. You can edit this file directly to make changes.

Now if you want to run Sobelow with the saved configuration, you can run Sobelow with the --config flag.

$ mix sobelow --config

False Positives

Sobelow favors over-reporting versus under-reporting. As such, you may find a number of false positives in a typical scan. These findings may be individually ignored by adding a # sobelow_skip comment, along with a list of modules, before the function definition.

# sobelow_skip ["Traversal"]
def vuln_func(...) do
  ...
end

Then, run the scan with the --skip flag.

$ mix sobelow --skip

Config and Vulnerable Dependency findings cannot be skipped in this way. For these, use the standard ignore option.

Modules

Findings categories are broken up into modules. These modules can then be used to either ignore classes of findings (via the ignore and skip options) or to get vulnerability details (via the details option).

This list, and other helpful information, can be found on the command line:

$ mix help sobelow

Updates

When scanning a project, Sobelow will occasionally check for updates, and will print an alert if a new version is available. Sobelow keeps track of the last update-check by creating a .sobelow file in the root of the scanned project.

If this functionality is not desired, the --private flag can be used with the scan.

$ mix sobelow --private