Added corsair scan

Corsair scan added as a zap script

Signed-off-by: javixeneize <javi.xeneize@gmail.com>

Author: javixeneize

CHANGELOG.md

@@ -6,6 +6,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 ## [Unreleased]
 ### Added
 - variant/CompoundCookies.js - An input vector script that handles splitting of compound cookies (Issue 6582).
+- active/corsair.py > An active scan script to check for CORS related issues.)
 
 ## [13] - 2021-10-14
 ### Fixed

active/corsair.py

@@ -0,0 +1,53 @@
+"""
+This is an adaptation of Corsair Scan (https://github.com/Santandersecurityresearch/corsair_scan) as a ZAP active scan script.
+This script will resend requests to all the sites being scanned in ZAP, injecting different origins. Then, it will read the value of Access-Control-Allow-Origin and based on that, it
+will assess if CORS is properly configured.
+"""
+import urlparse
+alertTitle = 'Corsair - CORS Misconfigured'
+alertDescription = "Cross Origin Resource Sharing (CORS) is misconfigured. \n"
+alertRisk = 2
+alertConfidence = 3
+alertSolution = "Configure CORS in a more restrictive way, to give access only the sites allowed to access your domain."
+alertInfo = "Cross-Origin Resource Sharing (CORS) is an HTTP-header based mechanism that allows a server to indicate any other origins (domain, scheme, or port) than its own from which a browser should permit loading of resources."
+cweID = 942
+wascID = 14
+
+SM_ORIGIN = 'https://example.com'
+SM_ORIGIN_NO_PROTOCOL = 'example.com'
+SM_ORIGIN_DOMAIN = 'example'
+
+"""
+In this method, we read the request performed and create a new request with a fake origin. Also, if the request already contains an origin header, we perform two extra requests:
+ 1 - Fake subdomain. It is, we set as origin a fake subdomain to validate if CORS is configured at domain level, or if it has granularity at subdomain level.
+ 2 - Fake postdomain. Here, we set a request using the existing origin as a subdomain for a fake domain. We do it to validate if CORS is misconfigured and it only checks if the expected value exists in the origin header.
+Then, we call cors_scan, which will send that request and validate the response.
+"""
+def scanNode(sas, msg):
+  origMsg = msg
+  msg = origMsg.cloneRequest() 
+  msg.getRequestHeader().setHeader("Origin", SM_ORIGIN)
+  cors_scan(sas,msg, "fake origin")
+  if origMsg.getRequestHeader().getHeader('Origin'):
+    parsed_url = urlparse.urlparse(origMsg.getRequestHeader().getHeader('Origin'))
+    subdomain= parsed_url.scheme + '://' + SM_ORIGIN_DOMAIN + '.' + parsed_url.netloc
+    postdomain = origMsg.getRequestHeader().getHeader('Origin') + '.' + SM_ORIGIN_NO_PROTOCOL
+    msg.getRequestHeader().setHeader("Origin", subdomain)
+    cors_scan(sas,msg, "fake subdomain")
+    msg.getRequestHeader().setHeader("Origin", postdomain)
+    cors_scan(sas,msg, "fake postdomain")
+
+"""
+cors_scan sends the request crafted by scanNode and reads the value of the Access-Control-Allow-Origin header. 
+If it is the origin reflected, * or NULL, we consider that CORS is misconfigured and raise an alert.
+"""
+def cors_scan(sas,msg, test_type):
+  sas.sendAndReceive(msg, True, False);
+  header = str(msg.getResponseHeader().getHeader("Access-Control-Allow-Origin"))
+  if (header in ['null', '*', msg.getRequestHeader().getHeader('Origin')]):
+    alertParam = "Test performed: Injecting a "+test_type
+    sas.raiseAlert(alertRisk, alertConfidence, alertTitle, alertDescription + alertParam,  msg.getRequestHeader().getURI().toString(), "Origin",
+       msg.getRequestHeader().getHeader('Origin'), alertInfo, alertSolution, msg.getRequestHeader().getHeader('Origin'), cweID, wascID, msg);
+
+def scan(sas, msg, param, value):
+  pass