CWE-669: Incorrect Resource Transfer Between Spheres

Description

The product does not properly transfer a resource/behavior to another sphere, or improperly imports a resource/behavior from another sphere, in a manner that provides unintended control over that resource.

Potential Impact

Confidentiality, Integrity

Read Application Data, Modify Application Data, Unexpected State

Demonstrative Examples

The following code demonstrates the unrestricted upload of a file with a Java servlet and a path traversal vulnerability. The action attribute of an HTML form is sending the upload file request to the Java servlet.

Good

<form action="FileUploadServlet" method="post" enctype="multipart/form-data">
                     Choose a file to upload:<input type="file" name="filename"/><br/><input type="submit" name="submit" value="Submit"/>
                     </form>

When submitted the Java servlet's doPost method will receive the request, extract the name of the file from the Http request header, read the file contents from the request and output the file to the local upload directory.

Bad

public class FileUploadServlet extends HttpServlet {
                     
                        ...
                           protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
                           
                              response.setContentType("text/html");PrintWriter out = response.getWriter();String contentType = request.getContentType();
                                 // the starting position of the boundary headerint ind = contentType.indexOf("boundary=");String boundary = contentType.substring(ind+9);
                                 String pLine = new String();String uploadLocation = new String(UPLOAD_DIRECTORY_STRING); //Constant value
                                 // verify that content type is multipart form dataif (contentType != null && contentType.indexOf("multipart/form-data") != -1) {
                                 
                                    // extract the filename from the Http headerBufferedReader br = new BufferedReader(new InputStreamReader(request.getInputStream()));...pLine = br.readLine();String filename = pLine.substring(pLine.lastIndexOf("\\"), pLine.lastIndexOf("\""));...
                                       // output the file to the local upload directorytry {
                                          BufferedWriter bw = new BufferedWriter(new FileWriter(uploadLocation+filename, true));for (String line; (line=br.readLine())!=null; ) {if (line.indexOf(boundary) == -1) {bw.write(line);bw.newLine();bw.flush();}} //end of for loopbw.close();
                                       
                                       
                                       } catch (IOException ex) {...}// output successful upload response HTML page
                                 }// output unsuccessful upload response HTML pageelse{...}
                           }...
                        
                     }

This code does not perform a check on the type of the file being uploaded (CWE-434). This could allow an attacker to upload any executable file or other file with malicious code.

Additionally, the creation of the BufferedWriter object is subject to relative path traversal (CWE-23). Since the code does not check the filename that is provided in the header, an attacker can use "../" sequences to write to files outside of the intended directory. Depending on the executing environment, the attacker may be able to specify arbitrary files to write to, leading to a wide variety of consequences, from code execution, XSS (CWE-79), or system crash.

This code includes an external script to get database credentials, then authenticates a user against the database, allowing access to the application.

Bad

//assume the password is already encrypted, avoiding CWE-312
                     
                     function authenticate($username,$password){
                        include("http://external.example.com/dbInfo.php");
                        
                        //dbInfo.php makes $dbhost, $dbuser, $dbpass, $dbname available
                        mysql_connect($dbhost, $dbuser, $dbpass) or die ('Error connecting to mysql');mysql_select_db($dbname);$query = 'Select * from users where username='.$username.' And password='.$password;$result = mysql_query($query);
                        if(mysql_numrows($result) == 1){mysql_close();return true;}else{mysql_close();return false;}
                     }

This code does not verify that the external domain accessed is the intended one. An attacker may somehow cause the external domain name to resolve to an attack server, which would provide the information for a false database. The attacker may then steal the usernames and encrypted passwords from real user login attempts, or simply allow themself to access the application without a real user account.

This example is also vulnerable to an Adversary-in-the-Middle AITM (CWE-300) attack.

This code either generates a public HTML user information page or a JSON response containing the same user information.

Bad

// API flag, output JSON if set
                     $json = $_GET['json']$username = $_GET['user']if(!$json){
                        $record = getUserRecord($username);foreach($record as $fieldName => $fieldValue){
                              if($fieldName == "email_address") {
                                    
                                       
                                       // skip displaying user emails
                                       continue;
                                 }else{writeToHtmlPage($fieldName,$fieldValue);}
                           }
                     }else{$record = getUserRecord($username);echo json_encode($record);}

The programmer is careful to not display the user's e-mail address when displaying the public HTML page. However, the e-mail address is not removed from the JSON response, exposing the user's e-mail address.

Real-World CVE Examples

CVE ID	Description
CVE-2021-22909	Chain: router's firmware update procedure uses curl with "-k" (insecure) option that disables certificate validation (CWE-295), allowing adversary-in-the-middle (AITM) compromise with a malicious firm
CVE-2023-5227	PHP-based FAQ management app does not check the MIME type for uploaded images
CVE-2005-0406	Some image editors modify a JPEG image, but the original EXIF thumbnail image is left intact within the JPEG. (Also an interaction error).

Frequently Asked Questions

What is CWE-669?

CWE-669 (Incorrect Resource Transfer Between Spheres) is a software weakness identified by MITRE's Common Weakness Enumeration. It is classified as a Class-level weakness. The product does not properly transfer a resource/behavior to another sphere, or improperly imports a resource/behavior from another sphere, in a manner that provides unintended control over that reso...

How can CWE-669 be exploited?

Attackers can exploit CWE-669 (Incorrect Resource Transfer Between Spheres) to read application data, modify application data, unexpected state. This weakness is typically introduced during the Architecture and Design, Implementation, Operation phase of software development.

How do I prevent CWE-669?

Follow secure coding practices, conduct code reviews, and use automated security testing tools (SAST/DAST) to detect this weakness early in the development lifecycle.

What is the severity of CWE-669?

CWE-669 is classified as a Class-level weakness (High abstraction). It has been observed in 3 real-world CVEs.