Custom POCs - scan4all

Overview

scan4all supports custom POC development through two primary methods:

Go POCs

Native Go code for complex detection logic and maximum performance

YAML POCs

Declarative YAML templates for simpler web vulnerability detection

Creating Go POCs

Step 1: Add Fingerprint

First, ensure the target technology has a fingerprint in pkg/fingerprint/localFingerData.go:

// Check if fingerprint exists
var FingerPrintData = map[string]string{
    "Apache Tomcat": "...",
    "Your-Technology": "detection-pattern",
}

If the fingerprint doesn’t exist, add it:

"YourApp": `(?i)(YourApp|X-Powered-By: YourApp)`,

Step 2: Create POC File

Create a new directory and Go file in pocs_go/:

mkdir -p pocs_go/yourapp
touch pocs_go/yourapp/CVE_2024_12345.go

Step 3: Write POC Function

package yourapp

import (
    "github.com/GhostTroops/scan4all/lib/util"
    "strings"
)

func CVE_2024_12345(url string) bool {
    // Build exploit URL
    exploitPath := "/api/vulnerable?param=test"
    targetURL := url + exploitPath
    
    // Send HTTP request
    req, err := util.HttpRequset(targetURL, "GET", "", false, nil)
    if err != nil {
        return false
    }
    
    // Check for vulnerability indicators
    if req.StatusCode == 200 && strings.Contains(req.Body, "vulnerable") {
        // Log the finding
        util.SendLog(targetURL, "CVE-2024-12345", "Vulnerability detected", "")
        return true
    }
    
    return false
}

Step 4: Register POC

Add detection logic to pocs_go/go_poc_check.go:

func POCcheck(wappalyzertechnologies []string, URL string, finalURL string, checklog4j bool) []string {
    var technologies []string
    
    for tech := range wappalyzertechnologies {
        caseStr := strings.ToLower(wappalyzertechnologies[tech])
        
        switch caseStr {
        // ... existing cases ...
        
        case "yourapp":  // Match fingerprint name (case-insensitive)
            if yourapp.CVE_2024_12345(URL) {
                technologies = append(technologies, "exp-YourApp|CVE-2024-12345")
            }
            if yourapp.CVE_2024_54321(URL) {
                technologies = append(technologies, "exp-YourApp|CVE-2024-54321")
            }
        }
    }
    
    return technologies
}

Step 5: Import Package

Add import at the top of go_poc_check.go:

import (
    // ... existing imports ...
    "github.com/GhostTroops/scan4all/pocs_go/yourapp"
)

Creating YAML POCs

Step 1: Verify Fingerprint

Ensure fingerprint exists in pkg/fingerprint/localFingerData.go.

Step 2: Create YAML File

Create a YAML file in pocs_yml/ymlFiles/ following the naming convention: Naming: {fingerprint}-{cve/vulnerability-id}-{description}.yml Example: yourapp-cve-2024-12345-rce.yml

Step 3: Write YAML POC

name: poc-yaml-yourapp-cve-2024-12345
manual: true
transport: http
set:
  rand: randomLowercase(8)
rules:
    v1:
        request:
            cache: true
            method: GET
            path: /api/check?param={{rand}}
            headers:
                User-Agent: "Mozilla/5.0"
        expression: |
            response.status == 200 && 
            response.body.bcontains(b"vulnerable")

YAML POC Components

Metadata Fields

name: poc-yaml-{target}-{vuln}
manual: true               # Requires manual verification
transport: http            # http, tcp, udp
set:                       # Variables
  var1: randomInt(1000, 9999)
  var2: randomLowercase(8)
  var3: "static value"

Request Configuration

request:
    cache: true              # Cache HTTP response
    method: GET              # GET, POST, PUT, DELETE, etc.
    path: /api/endpoint      # URL path
    headers:                 # Custom headers
        Content-Type: application/json
        X-Custom: value
    body: |                  # Request body
        {"key": "value"}
    follow_redirects: false  # Follow redirects

Expression Language

Response Checks:

response.status == 200
response.status >= 200 && response.status < 300
response.body.bcontains(b"text")
response.body.contains("string")
response.body.matches("regex")
response.headers["server"].contains("Apache")
response.latency > 5000

String Functions:

string.contains(str, "sub")
string.startsWith(str, "prefix")
string.endsWith(str, "suffix")

Encoding:

base64.encode("text")
base64.decode("dGV4dA==")
url.encode("text")
md5("text")
sha256("text")

Random Generation:

randomInt(min, max)
randomLowercase(length)
randomUppercase(length)
randomString(length)

Reverse Platform

For SSRF/RCE detection with DNS callbacks:

set:
  reverse: newReverse()
  randStr: randomLowercase(8)

rules:
    v1:
        request:
            path: /fetch?url=http://{{reverse.domain}}/{{randStr}}
        expression: |
            reverse.wait(5)  # Wait for callback

Requires configuration:

export ceyeapi="your-api-key"
export ceyedomain="your.ceye.io"

Utility Functions

HTTP Request Helpers

req, err := util.HttpRequset(url, "GET", "", false, nil)

Response Handling

if req, err := util.HttpRequset(url, "GET", "", false, nil); err == nil {
    // Check status code
    if req.StatusCode == 200 {
        // Check body content
        if util.StrContains(req.Body, "pattern") {
            // Vulnerability confirmed
        }
    }
    
    // Access headers
    serverHeader := req.Header.Get("Server")
    
    // Access final URL (after redirects)
    finalURL := req.RequestUrl
}

Logging Functions

// Send vulnerability finding
util.SendLog(url, "CVE-XXXX-XXXXX", "Description", "Additional info")

// Log POC execution
util.POClog(fmt.Sprintf("Testing %s with payload %s", url, payload))

// Standard logging
log.Println("Debug information")

Testing POCs

Local Testing

Build Project

go build

Test Against Target

./scan4all -host http://vulnerable-target.com

Enable Verbose Output

./scan4all -v -host http://vulnerable-target.com

Check Results

Look for your POC output in the results

Unit Testing

Create test file yourapp/CVE_2024_12345_test.go:

package yourapp

import (
    "testing"
)

func TestCVE_2024_12345(t *testing.T) {
    // Test against known vulnerable instance
    vulnerableURL := "http://vulnerable-test-instance.local"
    
    if !CVE_2024_12345(vulnerableURL) {
        t.Errorf("Failed to detect vulnerability on known vulnerable instance")
    }
    
    // Test against patched instance
    patchedURL := "http://patched-test-instance.local"
    
    if CVE_2024_12345(patchedURL) {
        t.Errorf("False positive on patched instance")
    }
}

Run tests:

go test ./pocs_go/yourapp/

Best Practices

Precise Detection

Use specific vulnerability indicators to minimize false positives

Error Handling

Always handle network errors and edge cases gracefully

Performance

Keep POCs fast - they execute on every matching target

Documentation

Document POC purpose, affected versions, and references

Security Considerations

Never include actual exploits that could cause damage
Detection only - POCs should detect, not exploit
Minimize impact - Use non-destructive payloads
Respect rate limits - Don’t overwhelm targets

Code Quality

Clear Naming

// Good
func CVE_2024_12345_RCE(url string) bool

// Bad
func check(u string) bool

Validation

// Validate input
if url == "" {
    return false
}

// Parse URL
if u, err := url.Parse(url); err != nil || u.Host == "" {
    return false
}

// Check response
if req == nil || req.Body == "" {
    return false
}

Comments

// CVE_2024_12345 detects authentication bypass in YourApp <= 1.2.3
// Vulnerability allows unauthenticated access to admin panel
// Reference: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2024-12345
func CVE_2024_12345(url string) bool {
    // Build exploit URL with bypass parameter
    exploitPath := "/admin?bypass=true"
    
    // Send request
    req, err := util.HttpRequset(url+exploitPath, "GET", "", false, nil)
    if err != nil {
        return false
    }
    
    // Check for admin panel indicators
    return req.StatusCode == 200 && 
           util.StrContains(req.Body, "Admin Dashboard")
}

Examples from Codebase

Simple Detection

// From pocs_go/tomcat/CVE_2017_12615.go
func CVE_2017_12615(szUrl string) bool {
    if req, err := util.HttpRequset(szUrl+"/vtset.txt", "PUT", "test", false, nil); err == nil {
        if req.StatusCode == 204 || req.StatusCode == 201 {
            util.SendLog(szUrl, "CVE-2017-12615", "Found vuln Tomcat", "")
            return true
        }
    }
    return false
}

Complex Detection

// From pocs_go/Springboot/CVE-2022-22965.go
func CVE_2022_22965(u string) bool {
    if oU, err := url.Parse(u); nil == err && oU.Host != "" {
        szUrl := oU.Scheme + "://" + oU.Host
        
        // Test for vulnerability pattern
        if req, err := util.HttpRequset(
            szUrl+"?class.module.classLoader%5b1%5d=1", 
            "GET", "", false, nil); err == nil {
            
            if req.StatusCode == 500 {
                // Confirm with second request
                if req2, err := util.HttpRequset(
                    szUrl+"?class.module.classLoader=1", 
                    "GET", "", false, nil); err == nil {
                    
                    if req2.StatusCode == 200 {
                        util.SendLog(szUrl, "CVE-2022-22965", 
                            "Spring4Shell detected", "")
                        return true
                    }
                }
            }
        }
    }
    return false
}

Troubleshooting

POC Not Executing

Possible causes:

Fingerprint not detected
Case mismatch in switch statement
POC not registered in go_poc_check.go
Package not imported

Solutions:

# Check fingerprint detection
./scan4all -v -host target.com | grep -i "fingerprint"

# Verify POC registration
grep -i "yourapp" pocs_go/go_poc_check.go

False Positives

Solutions:

Add more specific detection criteria
Verify multiple indicators
Test against patched versions
Check for edge cases

Build Errors

Common issues:

# Import cycle
# Solution: Reorganize package structure

# Undefined function
# Solution: Import required packages

# Syntax error
# Solution: Run go fmt and fix syntax

Go POCs

Explore existing Go POC implementations

Xray POCs

Learn about YAML POC structure

Fingerprinting

Understand fingerprint detection system

Development

Learn about scan4all architecture

Get Started

Core Features

Usage Guide

Configuration

POC & Detection

​Overview

Go POCs

YAML POCs

​Creating Go POCs

​Step 1: Add Fingerprint

​Step 2: Create POC File

​Step 3: Write POC Function

​Step 4: Register POC

​Step 5: Import Package

​Creating YAML POCs

​Step 1: Verify Fingerprint

​Step 2: Create YAML File

​Step 3: Write YAML POC

​YAML POC Components

​Utility Functions

​HTTP Request Helpers

​Response Handling

​Logging Functions

​Testing POCs

​Local Testing

​Unit Testing

​Best Practices

Precise Detection

Error Handling

Performance

Documentation

​Security Considerations

​Code Quality

​Examples from Codebase

​Simple Detection

​Complex Detection

​Troubleshooting

​Related Resources

Go POCs

Xray POCs

Fingerprinting

Development

Build docs developers (and LLMs) love

Overview

Creating Go POCs

Step 1: Add Fingerprint

Step 2: Create POC File

Step 3: Write POC Function

Step 4: Register POC

Step 5: Import Package

Creating YAML POCs

Step 1: Verify Fingerprint

Step 2: Create YAML File

Step 3: Write YAML POC

YAML POC Components

Utility Functions

HTTP Request Helpers

Response Handling

Logging Functions

Testing POCs

Local Testing

Unit Testing

Best Practices

Security Considerations

Code Quality

Examples from Codebase

Simple Detection

Complex Detection

Troubleshooting

Related Resources