CVE-2021-25955 (published 2021-08-15T21:15Z)

In “Dolibarr ERP CRM”, WYSIWYG Editor module, v2.8.1 to v13.0.2 are affected by a stored XSS vulnerability that allows low privileged application users to store malicious scripts in the “Private Note” field at “/adherents/note.php?id=1” endpoint. These scripts are executed in a victim’s browser when they open the page containing the vulnerable field. In the worst case, the victim who inadvertently triggers the attack is a highly privileged administrator. The injected scripts can extract the Session ID, which can lead to full Account takeover of the admin and due to other vulnerability (Improper Access Control on Private notes) a low privileged user can update the private notes which could lead to privilege escalation.

Severity: LOW
CVSS v2 base score: 3.5 (AV:N/AC:M/Au:S/C:N/I:P/A:N)
CVSS v3 base score: 9.0, CRITICAL (CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H)

Weakness information:
cwe_id: CWE-79
cwe_name: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
description: The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.
extended_description: 
            Cross-site scripting (XSS) vulnerabilities occur when:
            
               Untrusted data enters a web application, typically from a web request.
               The web application dynamically generates a web page that contains this untrusted data.
               During page generation, the application does not prevent the data from containing content that is executable by a web browser, such as JavaScript, HTML tags, HTML attributes, mouse events, Flash, ActiveX, etc.
               A victim visits the generated web page through a web browser, which contains malicious script that was injected using the untrusted data.
               Since the script comes from a web page that was sent by the web server, the victim's web browser executes the malicious script in the context of the web server's domain.
               This effectively violates the intention of the web browser's same-origin policy, which states that scripts in one domain should not be able to access resources or run code in a different domain.
            
            There are three main kinds of XSS:
            
               
                  Type 1: Reflected XSS (or Non-Persistent) - 
         			The server reads data directly from the HTTP request and reflects it back in the HTTP response. Reflected XSS exploits occur when an attacker causes a victim to supply dangerous content to a vulnerable web application, which is then reflected back to the victim and executed by the web browser. The most common mechanism for delivering malicious content is to include it as a parameter in a URL that is posted publicly or e-mailed directly to the victim. URLs constructed in this manner constitute the core of many phishing schemes, whereby an attacker convinces a victim to visit a URL that refers to a vulnerable site. After the site reflects the attacker's content back to the victim, the content is executed by the victim's browser.
               
                  Type 2: Stored XSS (or Persistent) - 
               The application stores dangerous data in a database, message forum, visitor log, or other trusted data store. At a later time, the dangerous data is subsequently read back into the application and included in dynamic content. From an attacker's perspective, the optimal place to inject malicious content is in an area that is displayed to either many users or particularly interesting users. Interesting users typically have elevated privileges in the application or interact with sensitive data that is valuable to the attacker. If one of these users executes malicious content, the attacker may be able to perform privileged operations on behalf of the user or gain access to sensitive data belonging to the user. For example, the attacker might inject XSS into a log message, which might not be handled properly when an administrator views the logs.
            
               
                  Type 0: DOM-Based XSS - 
               In DOM-based XSS, the client performs the injection of XSS into the page; in the other types, the server performs the injection. DOM-based XSS generally involves server-controlled, trusted script that is sent to the client, such as Javascript that performs sanity checks on a form before the user submits it. If the server-supplied script processes user-supplied data and then injects it back into the web page (such as with dynamic HTML), then DOM-based XSS is possible.
            
            
            Once the malicious script is injected, the attacker can perform a variety of malicious activities. The attacker could transfer private information, such as cookies that may include session information, from the victim's machine to the attacker. The attacker could send malicious requests to a web site on behalf of the victim, which could be especially dangerous to the site if the victim has administrator privileges to manage that site. Phishing attacks could be used to emulate trusted web sites and trick the victim into entering a password, allowing the attacker to compromise the victim's account on that web site. Finally, the script could exploit a vulnerability in the web browser itself possibly taking over the victim's machine, sometimes referred to as "drive-by hacking."
            In many cases, the attack can be launched without the victim even being aware of it. Even with careful users, attackers frequently use a variety of methods to encode the malicious portion of the attack, such as URL encoding or Unicode, so the request looks less suspicious.
         
         

Fix information:
repo_url: https://github.com/Dolibarr/dolibarr
commit_details: repo_url: https://github.com/Dolibarr/dolibarr
author: Laurent Destailleur
author_date: 2021-06-29 18:17:27+02:00
msg: Enhance the sanitizing.
repository: repo_url: https://github.com/Dolibarr/dolibarr
repo_name: Dolibarr/dolibarr
description: Dolibarr ERP CRM is a modern software package to manage your company or foundation's activity (contacts, suppliers, invoices, orders, stocks, agenda, accounting, ...). it's an open source Web application (written in PHP) designed for businesses of any sizes, foundations and freelancers.
repo_language: PHP
owner: Dolibarr
file_changes: filename: functions.lib.php
change_type: ModificationType.MODIFY
diff: @@ -778,8 +778,12 @@ function checkVal($out = '', $check = 'alphanohtml', $filter = null, $options =
 			do {
 				$oldstringtoclean = $out;
 
-				// We replace chars encoded with numeric HTML entities with real char (to avoid to have numeric entities used for obfuscation of injections)
-				$out = preg_replace_callback('/&#(x?[0-9][0-9a-f]+);/i', 'realCharForNumericEntities', $out);
+				// We replace chars from a/A to z/Z encoded with numeric HTML entities with the real char so we won't loose the chars at the next step.
+				// No need to use a loop here, this step is not to sanitize (this is done at next step, this is to try to save chars, even if they are
+				// using a non coventionnel way to be encoded, to not have them sanitized just after)
+				$out = preg_replace_callback('/&#(x?[0-9][0-9a-f]+;?)/i', 'realCharForNumericEntities', $out);
+
+				// Now we remove all remaining HTML entities staring with a number. We don't want such entities.
 				$out = preg_replace('/&#x?[0-9]+/i', '', $out);	// For example if we have j&#x61vascript with an entities without the ; to hide the 'a' of 'javascript'.
 
 				$out = dol_string_onlythesehtmltags($out, 0, 1, 1);

programming_language: PHP
filename: main.inc.php
change_type: ModificationType.MODIFY
diff: @@ -53,7 +53,7 @@ if (!empty($_SERVER['MAIN_SHOW_TUNING_INFO'])) {
 
 /**
  * Return the real char for a numeric entities.
- * This function is required by testSqlAndScriptInject().
+ * WARNING: This function is required by testSqlAndScriptInject() and the GETPOST 'restricthtml'. Regex calling must be similar.
  *
  * @param	string		$matches			String of numeric entity
  * @return	string							New value
@@ -61,17 +61,18 @@ if (!empty($_SERVER['MAIN_SHOW_TUNING_INFO'])) {
 function realCharForNumericEntities($matches)
 {
 	$newstringnumentity = $matches[1];
+	//print  '$newstringnumentity='.$newstringnumentity;
 
 	if (preg_match('/^x/i', $newstringnumentity)) {
-		$newstringnumentity = hexdec(preg_replace('/^x/i', '', $newstringnumentity));
+		$newstringnumentity = hexdec(preg_replace('/;$/', '', preg_replace('/^x/i', '', $newstringnumentity)));
 	}
 
-	// The numeric value we don't want as entities
+	// The numeric value we don't want as entities because they encode ascii char, and why using html entities on ascii except for haking ?
 	if (($newstringnumentity >= 65 && $newstringnumentity <= 90) || ($newstringnumentity >= 97 && $newstringnumentity <= 122)) {
 		return chr((int) $newstringnumentity);
 	}
 
-	return '&#'.$matches[1];
+	return '&#'.$matches[1];	// Value will be unchanged because regex was /&#(  )/
 }
 
 /**

programming_language: PHP
filename: SecurityTest.php
change_type: ModificationType.MODIFY
diff: @@ -345,7 +345,7 @@ class SecurityTest extends PHPUnit\Framework\TestCase
 		$_GET["param5"]="a_1-b";
 		$_POST["param6"]="&quot;&gt;<svg o&#110;load='console.log(&quot;123&quot;)'&gt;";
 		$_POST["param6b"]='<<<../>../>../svg><<<../>../>../animate =alert(1)>abc';
-		$_GET["param7"]='"c:\this is a path~1\aaa&#110;" abc<bad>def</bad>';
+		$_GET["param7"]='"c:\this is a path~1\aaa&#110; &#x&#x31;&#x31;&#x30;;" abc<bad>def</bad>';
 		$_POST["param8a"]="Hacker<svg o&#110;load='console.log(&quot;123&quot;)'";	// html tag is not closed so it is not detected as html tag but is still harmfull
 		$_POST['param8b']='<img src=x onerror=alert(document.location) t=';		// this is html obfuscated by non closing tag
 		$_POST['param8c']='< with space after is ok';
@@ -479,8 +479,8 @@ class SecurityTest extends PHPUnit\Framework\TestCase
 		$this->assertEquals('&quot;&gt;', $result);
 
 		$result=GETPOST("param7", 'restricthtml');
-		print __METHOD__." result=".$result."\n";
-		$this->assertEquals('"c:\this is a path~1\aaan" abcdef', $result);
+		print __METHOD__." result param7 = ".$result."\n";
+		$this->assertEquals('"c:\this is a path~1\aaan &#x;;;;" abcdef', $result);
 
 		$result=GETPOST("param12", 'restricthtml');
 		print __METHOD__." result=".$result."\n";
@@ -488,11 +488,11 @@ class SecurityTest extends PHPUnit\Framework\TestCase
 
 		$result=GETPOST("param13", 'restricthtml');
 		print __METHOD__." result=".$result."\n";
-		$this->assertEquals('n n &gt; &lt; &quot; <a href=\"alert(document.domain)\">XSS</a>', $result, 'Test that HTML entities are decoded with restricthtml, but only for common alpha chars');
+		$this->assertEquals('n n &gt; &lt; &quot; <a href=\"alert(document.domain)\">XSS</a>', $result, 'Test 13 that HTML entities are decoded with restricthtml, but only for common alpha chars');
 
 		$result=GETPOST("param13b", 'restricthtml');
 		print __METHOD__." result=".$result."\n";
-		$this->assertEquals('n n &gt; &lt; &quot; <a href=\"jvascript:alert(document.domain)\">XSS</a>', $result, 'Test that HTML entities are decoded with restricthtml, but only for common alpha chars');
+		$this->assertEquals('n n &gt; &lt; &quot; <a href=\"alert(document.domain)\">XSS</a>', $result, 'Test 13b that HTML entities are decoded with restricthtml, but only for common alpha chars');
 
 		// Special test for GETPOST of backtopage, backtolist or backtourl parameter
 

programming_language: PHP