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Mitigation Strategies Analysis for jwagenleitner/groovy-wslite

Mitigation Strategy: Strict Input Validation and Sanitization

Description:

  1. Identify All Input Points: List every point where groovy-wslite interacts with external data. This includes request parameters, headers, request bodies (if groovy-wslite processes them), response bodies from external services, and any configuration files used by the library that are then processed by Groovy.
  2. Define Whitelists: For each input point, create a whitelist specifying exactly what is allowed. This should be as restrictive as possible.
  3. Implement Validation: In the code, before any groovy-wslite processing that involves Groovy evaluation, validate the input against the whitelist. Reject anything that doesn't match.
  4. Sanitize (If Necessary): If you must accept input that contains potentially dangerous characters, use appropriate escaping functions before passing the data to any groovy-wslite component that might interpret it as Groovy code.
  5. Encoding: Use proper encoding when handling data.

Threats Mitigated:

  • Remote Code Execution (RCE) via Groovy Script Injection: (Severity: Critical) - Prevents attackers from injecting malicious Groovy code into parts of the application that groovy-wslite processes using Groovy.
  • XML External Entity (XXE) Injection: (Severity: High) - Reduces the risk of XXE if groovy-wslite's Groovy components are used to handle the XML.
  • Denial of Service (DoS) via Resource Exhaustion: (Severity: Medium) - Helps prevent DoS by limiting the size and complexity of input that Groovy might process.

Impact:

  • RCE: Significantly reduces the risk.
  • XXE: Reduces the risk.
  • DoS: Provides some protection.

Currently Implemented:

  • Example: "Partially implemented. Basic validation for numeric IDs in ServiceA.getData() where it's used in a RESTClient call, but no validation for XML responses in ServiceB.processResponse() that are then parsed with XmlSlurper within a groovy-wslite closure."

Missing Implementation:

  • Example: "Missing validation for XML responses in ServiceB.processResponse() that are parsed using XmlSlurper within a groovy-wslite closure. Missing whitelist validation for the query parameter in ServiceC.search() if that parameter influences Groovy code execution within groovy-wslite."

Mitigation Strategy: Avoid Dynamic Script Generation (within groovy-wslite usage)

Description:

  1. Review Code: Examine all code that uses groovy-wslite. Identify any instances where Groovy scripts or closures passed to or used within groovy-wslite are being constructed dynamically based on user input. This is the key distinction: we're focusing on Groovy code within the groovy-wslite context.
  2. Refactor to Static Scripts: If possible, rewrite the code to use pre-defined, static Groovy scripts or closures within the groovy-wslite calls.
  3. Parameterized Approach (If Unavoidable): If dynamic script generation within a groovy-wslite context is absolutely necessary, use a highly restricted, parameterized approach. Pass user input as data to the script/closure, not as part of the script itself.
  4. Example (Conceptual):
    • Bad (Vulnerable): 
      def userInput = params.userInput // Untrusted input
def client = new RESTClient('http://example.com')
client.get(path: '/data') { req ->
    // DANGEROUS: Direct injection into a Groovy closure
    req.queryString "query", "someStaticText ${userInput}"
}
    • Better (Parameterized): 
      def userInput = params.userInput // Untrusted input
def client = new RESTClient('http://example.com')
client.get(path: '/data') { req ->
    // Safer: Pass userInput as a separate parameter
    req.queryString 'query', 'someStaticText'
    req.queryString 'userInput', userInput
}
      (The best approach depends on how the API you're calling handles parameters. The key is to avoid string concatenation that builds Groovy code.)

Threats Mitigated:

  • Remote Code Execution (RCE) via Groovy Script Injection: (Severity: Critical) - Specifically targets RCE within the Groovy code used by groovy-wslite.

Impact:

  • RCE: Eliminates or drastically reduces the risk of RCE via script injection within the groovy-wslite context.

Currently Implemented:

  • Example: "Dynamic script generation is avoided in all RESTClient closures. SOAP requests in ServiceD use a parameterized approach within the groovy-wslite closures."

Missing Implementation:

  • Example: "Dynamic script generation is used within the closure passed to RESTClient.get() in ServiceE.generateReport(), directly incorporating user input into the Groovy script that processes the response."

Mitigation Strategy: Disable External Entities and DTDs (for XML within groovy-wslite)

Description:

  1. Identify XML Parsing within groovy-wslite: Locate all instances where groovy-wslite's Groovy components (e.g., closures, XmlSlurper used within a RESTClient or SOAPClient context) are used to parse XML data. This is crucial: we're focusing on XML parsing done by Groovy code within the groovy-wslite usage.
  2. Configure XML Parser: Modify the code to explicitly configure the underlying XML parser used within the groovy-wslite context to disable external entities and DTDs. 
    // Example (adjust as needed - this is within a groovy-wslite context)
def client = new RESTClient('http://example.com')
client.parser.'text/xml' = { resp, reader ->
    def factory = javax.xml.parsers.SAXParserFactory.newInstance()
    factory.setFeature("http://xml.org/sax/features/external-general-entities", false)
    factory.setFeature("http://xml.org/sax/features/external-parameter-entities", false)
    factory.setFeature("http://apache.org/xml/features/disallow-doctype-decl", true)
    def parser = factory.newSAXParser()
    // Use the configured parser within XmlSlurper or similar
    def root = new XmlSlurper(parser).parse(reader)
    return root
}
  3. Test: Thoroughly test.

Threats Mitigated:

  • XML External Entity (XXE) Injection: (Severity: High) - Prevents XXE attacks where the XML parsing is handled by Groovy code within groovy-wslite.

Impact:

  • XXE: Effectively eliminates the risk of XXE attacks if implemented correctly within the groovy-wslite context.

Currently Implemented:

  • Example: "External entities and DTDs are disabled for all XML parsing done by XmlSlurper within RESTClient response closures."

Missing Implementation:

  • Example: "XML parsing within the groovy-wslite closure in LegacySOAPClient.handleResponse() does not disable external entities."

Mitigation Strategy: Set Timeouts and Response Size Limits (within groovy-wslite calls)

Description:

  1. Identify Network Calls: Locate all instances where groovy-wslite makes network requests (e.g., RESTClient, SOAPClient).
  2. Set Timeouts: Configure timeouts for all network requests made by groovy-wslite. 
    def client = new RESTClient('http://example.com')
client.timeout = 5000 // 5 seconds
  3. Set Response Size Limits: Implement limits on the size of responses that groovy-wslite will process, especially if those responses are then processed by Groovy code. This is often done within the groovy-wslite closures.
  4. Test: Verify.

Threats Mitigated:

  • Denial of Service (DoS) via Resource Exhaustion: (Severity: Medium) - Prevents DoS attacks that rely on slow or excessively large responses being processed by groovy-wslite's Groovy components.

Impact:

  • DoS: Significantly reduces the risk.

Currently Implemented:

  • Example: "Timeouts are set for all RESTClient instances. Response size limits are checked within the response processing closures for REST responses in ServiceA."

Missing Implementation:

  • Example: "No response size limits are implemented for SOAP responses processed by Groovy code within groovy-wslite closures. Timeouts are not set for LegacySOAPClient."

Mitigation Strategy: Sandboxing (of Groovy code within groovy-wslite)

Description:

  1. Assess Necessity: Determine if dynamic Groovy execution within the groovy-wslite context is absolutely necessary.
  2. Choose a Sandboxing Technique: If dynamic Groovy execution within groovy-wslite is required, use SecureASTCustomizer. This is the most direct way to control the Groovy code executed as part of groovy-wslite's operation. 
    import org.codehaus.groovy.control.customizers.SecureASTCustomizer
import org.codehaus.groovy.control.CompilerConfiguration

def secure = new SecureASTCustomizer()
// ... configure SecureASTCustomizer as shown in previous examples ...

def config = new CompilerConfiguration()
config.addCompilationCustomizers(secure)

// Example using RESTClient (apply the configuration to the GroovyShell)
def client = new RESTClient('http://example.com', config) // Pass the config

client.get(path: '/data') { req ->
    // The closure here will be executed in the sandboxed environment
    // ...
}
  3. Restrict Permissions: Carefully configure the sandbox.
  4. Test Thoroughly: Extensively test.

Threats Mitigated:

  • Remote Code Execution (RCE) via Groovy Script Injection: (Severity: Critical) - Significantly reduces the risk, even if malicious code is injected into the Groovy portions of groovy-wslite's operation.

Impact:

  • RCE: Provides a strong layer of defense.

Currently Implemented:

  • Example: "Sandboxing is implemented using SecureASTCustomizer for all Groovy closures used within RESTClient calls. File system and network access are disabled within those closures."

Missing Implementation:

  • Example: "Sandboxing is not currently implemented for Groovy code used within SOAPClient calls. We should apply SecureASTCustomizer to the Groovy closures used for processing SOAP responses."