threat-modeling.md

Threat Model Analysis for briannesbitt/carbon

Threat: System Time Manipulation via setTestNow()

• Threat: System Time Manipulation via setTestNow()

  • Description: An attacker provides crafted input (e.g., through a hidden form field, URL parameter, or manipulated API request) that is ultimately used, directly or indirectly, to call Carbon::setTestNow() with a malicious date/time value. This changes the application's perception of "now" for all subsequent Carbon operations. This is a direct misuse of a Carbon function.
  • Impact:
    • Bypass time-based access controls (e.g., accessing content outside of allowed hours).
    • Trigger premature or delayed execution of scheduled tasks.
    • Corrupt data integrity by recording incorrect timestamps.
    • Manipulate financial transactions or reporting based on time.
  • Carbon Component Affected: Carbon::setTestNow() function, and any functionality relying on the current time (Carbon::now(), Carbon::today(), etc.).
  • Risk Severity: Critical
  • Mitigation Strategies:
    • Strictly prohibit the use of Carbon::setTestNow() in production code based on any user-supplied input. This function should be exclusively for testing.
    • Implement robust input validation and sanitization to prevent any user-controlled data from influencing the system's time.
    • If a "testing mode" is absolutely required in a production-like environment, use a highly restricted, authenticated, and auditable mechanism completely separate from normal user input channels.

Threat: Timezone Manipulation via User Input

• Threat: Timezone Manipulation via User Input

  • Description: An attacker provides a malicious or unexpected timezone string (e.g., "Evil/Timezone", or a timezone with extreme offsets) through a form field, API parameter, or other input vector. This timezone is then used in Carbon operations like Carbon::parse(), Carbon::createFromFormat(), or when setting the timezone on a Carbon instance. This directly impacts how Carbon interprets and processes date/time data.
  • Impact:
    • Incorrect date/time calculations, leading to data corruption or logic errors.
    • Circumventing time-based restrictions by shifting the perceived time.
    • Potential denial-of-service if an extremely complex or invalid timezone is processed (though this is less likely to be directly exploitable through Carbon alone, it's a consequence of using the input with Carbon).
    • Information disclosure if timezone handling reveals server location or configuration (again, less direct, but a consequence of the misuse).
  • Carbon Component Affected: Carbon::parse(), Carbon::createFromFormat(), setTimezone() method, and any functions that accept a timezone argument.
  • Risk Severity: High
  • Mitigation Strategies:
    • Strictly validate user-provided timezone input against a whitelist of known, safe timezone identifiers (IANA timezone database names, e.g., "America/Los_Angeles"). Never allow arbitrary strings.
    • Use a configuration setting to define the application's default timezone, and avoid relying on the server's default timezone.
    • Store user timezones in a validated, secure format (e.g., database field with a limited set of allowed values).
    • Convert all dates and times to UTC for internal storage and calculations, converting to user-specific timezones only for display.

Threat: Malformed Date String Parsing (DoS)

• Threat: Malformed Date String Parsing (DoS)

  • Description: An attacker submits an extremely long, complex, or intentionally malformed date/time string to a function like Carbon::parse() or Carbon::createFromFormat(). This causes excessive CPU and memory consumption within the Carbon library, potentially leading to a denial-of-service. This is a direct attack on Carbon's parsing capabilities.
  • Impact:
    • Application becomes unresponsive or crashes.
    • Other users are unable to access the application.
    • Potential resource exhaustion on the server.
  • Carbon Component Affected: Carbon::parse(), Carbon::createFromFormat(), and other parsing functions.
  • Risk Severity: High
  • Mitigation Strategies:
    • Implement strict input validation to limit the length and allowed characters of date/time strings before passing them to Carbon. Use regular expressions to enforce expected formats.
    • Set a timeout on Carbon parsing operations to prevent them from running indefinitely.
    • Implement rate limiting to prevent an attacker from submitting a large number of malformed date strings in a short period.
    • Use a well-defined date/time format (e.g., ISO 8601) whenever possible, and avoid relying on Carbon's "fuzzy" parsing capabilities for user-supplied input.

Threat: Unsafe usage of createFromFormat

• Threat: Unsafe usage of createFromFormat

  • Description: An attacker can control the format string passed to createFromFormat, potentially leading to unexpected behavior or vulnerabilities. If the attacker can inject format specifiers, they might be able to influence the parsing process in unintended ways.
  • Impact:
    • Unexpected date/time interpretation.
    • Potential for format string vulnerabilities if the format string is used in other contexts (although less likely directly within Carbon, the misuse creates the vulnerability).
  • Carbon Component Affected: Carbon::createFromFormat()
  • Risk Severity: High
  • Mitigation Strategies:
    • Never allow user input to directly control the format string passed to createFromFormat. Use predefined, static format strings.
    • If the format needs to be dynamic, generate it programmatically based on a strictly controlled set of options, and thoroughly validate the generated format string before using it. Ensure no user-supplied data can influence the format specifiers.