vulnerabilities-workflow-1.md

Here is the combined list of vulnerabilities, formatted as markdown, with duplicate vulnerabilities removed (though in this case, there were no duplicates, just different presentations of vulnerability findings).

Combined Vulnerability List

This list consolidates identified vulnerabilities, detailing their descriptions, impacts, mitigations, and steps for exploitation and testing.

1. Unrestricted Environment Variable Override

• Description: The gotenv package's override functions (gotenv.OverLoad and gotenv.OverApply) allow unconditional setting of environment variables using externally supplied input. If an attacker can control the content of the input file or stream used by these functions, they can inject arbitrary key-value pairs into the application's environment. This is particularly dangerous if an external interface allows the attacker to provide a malicious environment file, potentially overriding security-critical settings like database credentials, system PATH, or other configuration parameters. Step by step trigger:

  1. Identify a publicly accessible application feature that utilizes gotenv.OverLoad or gotenv.OverApply on attacker-controlled input (e.g., via a file upload or API endpoint accepting raw .env content).
  2. Construct a malicious environment file containing entries to override critical settings, such as:

     PATH=/malicious/bin
     DB_PASSWORD=evilpassword
     

  3. Submit this crafted payload as input to the override loader function (gotenv.OverApply or gotenv.OverLoad).
  4. The gotenv function processes the input, invoking setenv(key, val, override) which, with override=true, sets each environment variable without any validation.
  5. Consequently, the application's critical configuration is modified according to the attacker's input.

• Impact: By successfully overriding environment variables, an attacker gains the ability to alter the application's runtime configuration. The consequences can be severe, potentially leading to authentication bypass, redirection of application connections, execution of unauthorized binaries (if PATH or similar variables are compromised), and enabling further attacks such as privilege escalation. In scenarios where configuration is integral to application security, this vulnerability can be critically damaging.

• Vulnerability Rank: High

• Currently Implemented Mitigations:

  • The non-override functions (gotenv.Load and gotenv.Apply) are designed to prevent overriding existing environment variables. They check for pre-existing values and do not modify them. However, the override functions (OverLoad/OverApply) are explicitly designed to disregard any existing environment settings and override them based on the input.

• Missing Mitigations:

  • Lack of input validation or sanitization on the keys and values provided in override mode.
  • Absence of a whitelist or restrictions on which environment variables can be updated.
  • No authentication or authorization checks on the source of the .env file or input stream being processed.

• Preconditions:

  • The attacker must be able to supply or modify the .env file (or the io.Reader input) that is processed by the override functions.
  • The application must be using gotenv.OverLoad or gotenv.OverApply on input that is directly or indirectly controllable by an external attacker.

• Source Code Analysis:

  • Examining gotenv.go, the OverLoad function is implemented as a direct call to loadenv(true, filenames...).
  • The loadenv helper function iterates through the provided filenames and parses each file's content using parset(f, override). The override boolean flag is passed along, set to true for overload operations.
  • Within the parset function's loop, each parsed key-value pair is processed by calling setenv(key, val, override).
  • The setenv function, when override is true, directly executes os.Setenv(key, val) without any validation or filtering of the key or value.
  • This code path allows an attacker who controls the input file to arbitrarily set environment variables within the application's process.

• Security Test Case:

  1. Deploy a test instance of the application featuring an endpoint (or similar mechanism) that accepts an environment file and utilizes gotenv.OverApply to reload configuration.
  2. Construct a malicious .env payload, for example:

     PATH=/malicious/bin
     SECRET_KEY=attackers_secret
     

  3. Submit this payload through the publicly accessible endpoint designed to process environment files.
  4. After processing the payload, use internal application monitoring or logging to retrieve the values of environment variables PATH and SECRET_KEY using os.Getenv("PATH") and os.Getenv("SECRET_KEY").
  5. Verify that the retrieved environment variables reflect the attacker-supplied values, confirming the successful overriding of the application's environment configuration.

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2. Arbitrary File Write via Path Traversal in Write Function

• Description: The Write function in the gotenv package is designed to serialize the environment map and write it to a file path specified by the caller. It creates necessary directories using os.MkdirAll(filepath.Dir(filename), 0o775) and then creates or truncates the file using os.Create(filename). However, the function lacks any sanitization or validation of the provided filename. Consequently, an attacker who can control this filename parameter can inject directory traversal sequences (e.g., "../../") to write files to arbitrary locations outside the intended directory structure. Step by step trigger:

  1. Identify an externally accessible application feature (like an API endpoint) that utilizes the Write function and derives the filename parameter, at least partially, from user-controlled input.
  2. Craft a malicious filename string that incorporates directory traversal sequences, such as:

     ../../etc/passwd
     

     (or any other sensitive path that the application process has write permissions for).
  3. Provide valid environment content along with this malicious filename.
  4. Trigger the application endpoint or functionality that calls the Write function with the crafted filename.
  5. Verify that the file is written to the unintended location specified in the malicious filename, demonstrating the ability to create or overwrite files outside the intended safe directory.

• Impact: Successful exploitation of this vulnerability enables arbitrary file write capabilities. This can lead to severe consequences, including corruption of system configuration files, injection of malicious configurations, privilege escalation, and potentially remote code execution if critical system files or scripts are targeted and overwritten. The severity is amplified by the function's unrestricted acceptance of any file path.

• Vulnerability Rank: Critical

• Currently Implemented Mitigations:

  • The Write function currently lacks any implemented checks for the validity or safety of the provided file path. It directly accepts the filename and proceeds to write to it without any form of validation or sanitization.

• Missing Mitigations:

  • No sanitization or validation of the filename to prevent directory traversal attacks (e.g., blocking sequences like "../").
  • No restrictions on using absolute versus relative file paths, which could help confine file writes.
  • Absence of confinement mechanisms to restrict file write operations to a designated safe or configured directory.

• Preconditions:

  • The attacker needs to have control over the filename parameter that is passed to the Write function. This usually implies that the application exposes an interface where the filename is derived, at least in part, from external, attacker-controlled input.
  • The application process must have sufficient filesystem permissions to write to the target directory specified in the malicious path.

• Source Code Analysis:

  • In gotenv.go, the Write function is structured as follows:
    • It first calls Marshal(env) to convert the environment map into a string format.
    • Then, it attempts to ensure the existence of the directory path by calling:

      if err := os.MkdirAll(filepath.Dir(filename), 0o775); err != nil { … }

      Notably, filepath.Dir(filename) is computed directly from the attacker-controlled input filename without any sanitization.
    • Subsequently, it calls os.Create(filename) to create or truncate the file at the attacker-specified location.
  • Because no checks are performed on the structure or contents of the filename, an attacker-supplied string can easily include path traversal sequences to navigate outside of any intended safe directory and write to arbitrary locations.

• Security Test Case:

  1. Set up a controlled test environment and expose an API endpoint that accepts both environment variable data and a filename parameter. Configure this endpoint to use gotenv.Write to save the environment data to the specified file.
  2. Construct a request with a malicious filename, such as ../../tmp/malicious.env (or another path appropriate for your test environment), and include benign environment variable content.
  3. Send this crafted request to the API endpoint.
  4. After processing, examine the filesystem to check if the file was written to the unintended location. Verify if ../../tmp/malicious.env exists and contains the expected data.
  5. Confirm that this behavior demonstrates the vulnerability, proving the lack of proper path validation and the ability to write files to arbitrary locations using path traversal.