• /login [Referer HTTP header]
• /login [User-Agent HTTP header]

Reflected cross-site scripting vulnerabilities arise when data is copied from a request and echoed into the application's immediate response in an unsafe way. An attacker can use the vulnerability to construct a request that, if issued by another application user, will cause JavaScript code supplied by the attacker to execute within the user's browser in the context of that user's session with the application.

The attacker-supplied code can perform a wide variety of actions, such as stealing the victim's session token or login credentials, performing arbitrary actions on the victim's behalf, and logging their keystrokes.

Users can be induced to issue the attacker's crafted request in various ways. For example, the attacker can send a victim a link containing a malicious URL in an email or instant message. They can submit the link to popular web sites that allow content authoring, for example in blog comments. And they can create an innocuous looking web site that causes anyone viewing it to make arbitrary cross-domain requests to the vulnerable application (using either the GET or the POST method).

The security impact of cross-site scripting vulnerabilities is dependent upon the nature of the vulnerable application, the kinds of data and functionality that it contains, and the other applications that belong to the same domain and organization. If the application is used only to display non-sensitive public content, with no authentication or access control functionality, then a cross-site scripting flaw may be considered low risk. However, if the same application resides on a domain that can access cookies for other more security-critical applications, then the vulnerability could be used to attack those other applications, and so may be considered high risk. Similarly, if the organization that owns the application is a likely target for phishing attacks, then the vulnerability could be leveraged to lend credibility to such attacks, by injecting Trojan functionality into the vulnerable application and exploiting users' trust in the organization in order to capture credentials for other applications that it owns. In many kinds of application, such as those providing online banking functionality, cross-site scripting should always be considered high risk.

In most situations where user-controllable data is copied into application responses, cross-site scripting attacks can be prevented using two layers of defenses:

• Input should be validated as strictly as possible on arrival, given the kind of content that it is expected to contain. For example, personal names should consist of alphabetical and a small range of typographical characters, and be relatively short; a year of birth should consist of exactly four numerals; email addresses should match a well-defined regular expression. Input which fails the validation should be rejected, not sanitized.
• User input should be HTML-encoded at any point where it is copied into application responses. All HTML metacharacters, including < > " ' and =, should be replaced with the corresponding HTML entities (&lt; &gt; etc).

In cases where the application's functionality allows users to author content using a restricted subset of HTML tags and attributes (for example, blog comments which allow limited formatting and linking), it is necessary to parse the supplied HTML to validate that it does not use any dangerous syntax; this is a non-trivial task.

• Cross-site scripting
• Reflected cross-site scripting
• Using Burp to Find XSS issues

• CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
• CWE-80: Improper Neutralization of Script-Related HTML Tags in a Web Page (Basic XSS)
• CWE-116: Improper Encoding or Escaping of Output
• CWE-159: Failure to Sanitize Special Element

The application fails to prevent users from connecting to it over unencrypted connections. An attacker able to modify a legitimate user's network traffic could bypass the application's use of SSL/TLS encryption, and use the application as a platform for attacks against its users. This attack is performed by rewriting HTTPS links as HTTP, so that if a targeted user follows a link to the site from an HTTP page, their browser never attempts to use an encrypted connection. The sslstrip tool automates this process.

To exploit this vulnerability, an attacker must be suitably positioned to intercept and modify the victim's network traffic.This scenario typically occurs when a client communicates with the server over an insecure connection such as public Wi-Fi, or a corporate or home network that is shared with a compromised computer. Common defenses such as switched networks are not sufficient to prevent this. An attacker situated in the user's ISP or the application's hosting infrastructure could also perform this attack. Note that an advanced adversary could potentially target any connection made over the Internet's core infrastructure.

The application should instruct web browsers to only access the application using HTTPS. To do this, enable HTTP Strict Transport Security (HSTS) by adding a response header with the name 'Strict-Transport-Security' and the value 'max-age=expireTime', where expireTime is the time in seconds that browsers should remember that the site should only be accessed using HTTPS. Consider adding the 'includeSubDomains' flag if appropriate.

Note that because HSTS is a "trust on first use" (TOFU) protocol, a user who has never accessed the application will never have seen the HSTS header, and will therefore still be vulnerable to SSL stripping attacks. To mitigate this risk, you can optionally add the 'preload' flag to the HSTS header, and submit the domain for review by browser vendors.

• HTTP Strict Transport Security
• sslstrip
• HSTS Preload Form

• CWE-523: Unprotected Transport of Credentials

Path-relative style sheet import vulnerabilities arise when the following conditions hold:

1. A response contains a style sheet import that uses a path-relative URL (for example, the page at "/original-path/file.php" might import "styles/main.css").
2. When handling requests, the application or platform tolerates superfluous path-like data following the original filename in the URL (for example, "/original-path/file.php/extra-junk/"). When superfluous data is added to the original URL, the application's response still contains a path-relative stylesheet import.
3. The response in condition 2 can be made to render in a browser's quirks mode, either because it has a missing or old doctype directive, or because it allows itself to be framed by a page under an attacker's control.
4. When a browser requests the style sheet that is imported in the response from the modified URL (using the URL "/original-path/file.php/extra-junk/styles/main.css"), the application returns something other than the CSS response that was supposed to be imported. Given the behavior described in condition 2, this will typically be the same response that was originally returned in condition 1.
5. An attacker has a means of manipulating some text within the response in condition 4, for example because the application stores and displays some past input, or echoes some text within the current URL.

Given the above conditions, an attacker can execute CSS injection within the browser of the target user. The attacker can construct a URL that causes the victim's browser to import as CSS a different URL than normal, containing text that the attacker can manipulate.

Being able to inject arbitrary CSS into the victim's browser may enable various attacks, including:

• Executing arbitrary JavaScript using IE's expression() function.
• Using CSS selectors to read parts of the HTML source, which may include sensitive data such as anti-CSRF tokens.
• Capturing any sensitive data within the URL query string by making a further style sheet import to a URL on the attacker's domain, and monitoring the incoming Referer header.

The root cause of the vulnerability can be resolved by not using path-relative URLs in style sheet imports. Aside from this, attacks can also be prevented by implementing all of the following defensive measures:

• Setting the HTTP response header "X-Frame-Options: deny" in all responses. One method that an attacker can use to make a page render in quirks mode is to frame it within their own page that is rendered in quirks mode. Setting this header prevents the page from being framed.
• Setting a modern doctype (e.g. "<!doctype html>") in all HTML responses. This prevents the page from being rendered in quirks mode (unless it is being framed, as described above).
• Setting the HTTP response header "X-Content-Type-Options: nosniff" in all responses. This prevents the browser from processing a non-CSS response as CSS, even if another page loads the response via a style sheet import.

• Detecting and exploiting path-relative stylesheet import (PRSSI) vulnerabilities

• CWE-16: Configuration

Application responses may depend systematically on the presence or absence of the Referer header in requests. This behavior does not necessarily constitute a security vulnerability, and you should investigate the nature of and reason for the differential responses to determine whether a vulnerability is present.

Common explanations for Referer-dependent responses include:

• Referer-based access controls, where the application assumes that if you have arrived from one privileged location then you are authorized to access another privileged location. These controls can be trivially defeated by supplying an accepted Referer header in requests for the vulnerable function.
• Attempts to prevent cross-site request forgery attacks by verifying that requests to perform privileged actions originated from within the application itself and not from some external location. Such defenses are often not robust, and can be bypassed by removing the Referer header entirely.
• Delivery of Referer-tailored content, such as welcome messages to visitors from specific domains, search-engine optimization (SEO) techniques, and other ways of tailoring the user's experience. Such behaviors often have no security impact; however, unsafe processing of the Referer header may introduce vulnerabilities such as SQL injection and cross-site scripting. If parts of the document (such as META keywords) are updated based on search engine queries contained in the Referer header, then the application may be vulnerable to persistent code injection attacks, in which search terms are manipulated to cause malicious content to appear in responses served to other application users.

The Referer header is not a robust foundation on which to build access controls. Any such measures should be replaced with more secure alternatives that are not vulnerable to Referer spoofing.

If the contents of responses is updated based on Referer data, then the same defenses against malicious input should be employed here as for any other kinds of user-supplied data.

• CWE-16: Configuration
• CWE-213: Intentional Information Exposure

Application responses may depend systematically on the value of the User-Agent header in requests. This behavior does not itself constitute a security vulnerability, but may point towards additional attack surface within the application, which may contain vulnerabilities.

This behavior often arises because applications provide different user interfaces for desktop and mobile users. Mobile interfaces have often been less thoroughly tested for vulnerabilities such as cross-site scripting, and often have simpler authentication and session handling mechanisms that may contain problems that are not present in the full interface.

To review the interface provided by the alternate User-Agent header, you can configure a match/replace rule in Burp Proxy to modify the User-Agent header in all requests, and then browse the application in the normal way using your normal browser.

• CWE-16: Configuration

• /home [name of an arbitrarily supplied URL parameter]
• /login [Referer HTTP header]
• /login [User-Agent HTTP header]
• /login [destinationurl parameter]
• /login [name of an arbitrarily supplied URL parameter]
• /static/css/login-style.css [URL path filename]
• /static/css/login-style.css [URL path folder 2]
• /static/fonts/fontawesome-pro/css/all.min.css [URL path filename]
• /static/fonts/fontawesome-pro/css/all.min.css [URL path folder 2]
• /static/fonts/fontawesome-pro/css/all.min.css [URL path folder 3]
• /static/fonts/fontawesome-pro/css/all.min.css [URL path folder 4]
• /static/js/login.js [URL path filename]
• /static/js/login.js [URL path folder 2]
• /static/third-party/buefy.min.css [URL path filename]
• /static/third-party/firebase/firebase-app.js [URL path filename]
• /static/third-party/firebase/firebase-app.js [URL path folder 2]
• /static/third-party/firebase/firebase-app.js [URL path folder 3]
• /static/third-party/firebaseui/dist/firebaseui.css [URL path filename]
• /static/third-party/firebaseui/dist/firebaseui.css [URL path folder 2]
• /static/third-party/firebaseui/dist/firebaseui.css [URL path folder 3]
• /static/third-party/firebaseui/dist/firebaseui.css [URL path folder 4]
• /static/third-party/firebaseui/dist/firebaseui.js [URL path filename]
• /static/third-party/firebaseui/dist/firebaseui.js [URL path folder 3]
• /static/third-party/firebaseui/dist/firebaseui.js [URL path folder 4]
• /static/third-party/vue.js [URL path filename]

Reflection of input arises when data is copied from a request and echoed into the application's immediate response.

Input being returned in application responses is not a vulnerability in its own right. However, it is a prerequisite for many client-side vulnerabilities, including cross-site scripting, open redirection, content spoofing, and response header injection. Additionally, some server-side vulnerabilities such as SQL injection are often easier to identify and exploit when input is returned in responses. In applications where input retrieval is rare and the environment is resistant to automated testing (for example, due to a web application firewall), it might be worth subjecting instances of it to focused manual testing.

• CWE-20: Improper Input Validation
• CWE-116: Improper Encoding or Escaping of Output

• https://myharbourshare.com/login

• https://browser.sentry-cdn.com/6.2.3/bundle.min.js
• https://browser.sentry-cdn.com/6.2.3/vue.min.js
• https://knowledgebase.harbourshare.com/knowledge/logging-info-support
• https://www.harbourshare.com/
• https://www.harbourshare.com/privacy-policy
• https://www.harbourshare.com/terms-of-service

When a web browser makes a request for a resource, it typically adds an HTTP header, called the "Referer" header, indicating the URL of the resource from which the request originated. This occurs in numerous situations, for example when a web page loads an image or script, or when a user clicks on a link or submits a form.

If the resource being requested resides on a different domain, then the Referer header is still generally included in the cross-domain request. If the originating URL contains any sensitive information within its query string, such as a session token, then this information will be transmitted to the other domain. If the other domain is not fully trusted by the application, then this may lead to a security compromise.

You should review the contents of the information being transmitted to other domains, and also determine whether those domains are fully trusted by the originating application.

Today's browsers may withhold the Referer header in some situations (for example, when loading a non-HTTPS resource from a page that was loaded over HTTPS, or when a Refresh directive is issued), but this behavior should not be relied upon to protect the originating URL from disclosure.

Note also that if users can author content within the application then an attacker may be able to inject links referring to a domain they control in order to capture data from URLs used within the application.

Applications should never transmit any sensitive information within the URL query string. In addition to being leaked in the Referer header, such information may be logged in various locations and may be visible on-screen to untrusted parties. If placing sensitive information in the URL is unavoidable, consider using the Referer-Policy HTTP header to reduce the chance of it being disclosed to third parties.

• Referer Policy

• CWE-200: Information Exposure

• https://browser.sentry-cdn.com/6.2.3/bundle.min.js
• https://browser.sentry-cdn.com/6.2.3/vue.min.js

When an application includes a script from an external domain, this script is executed by the browser within the security context of the invoking application. The script can therefore do anything that the application's own scripts can do, such as accessing application data and performing actions within the context of the current user.

If you include a script from an external domain, then you are trusting that domain with the data and functionality of your application, and you are trusting the domain's own security to prevent an attacker from modifying the script to perform malicious actions within your application.

Scripts should ideally not be included from untrusted domains. Applications that rely on static third-party scripts should consider using Subresource Integrity to make browsers verify them, or copying the contents of these scripts onto their own domain and including them from there. If that is not possible (e.g. for licensing reasons) then consider reimplementing the script's functionality within application code.

• Subresource Integrity

• CWE-829: Inclusion of Functionality from Untrusted Control Sphere

If a page fails to set an appropriate X-Frame-Options or Content-Security-Policy HTTP header, it might be possible for a page controlled by an attacker to load it within an iframe. This may enable a clickjacking attack, in which the attacker's page overlays the target application's interface with a different interface provided by the attacker. By inducing victim users to perform actions such as mouse clicks and keystrokes, the attacker can cause them to unwittingly carry out actions within the application that is being targeted. This technique allows the attacker to circumvent defenses against cross-site request forgery, and may result in unauthorized actions.

Note that some applications attempt to prevent these attacks from within the HTML page itself, using "framebusting" code. However, this type of defense is normally ineffective and can usually be circumvented by a skilled attacker.

You should determine whether any functions accessible within frameable pages can be used by application users to perform any sensitive actions within the application.

To effectively prevent framing attacks, the application should return a response header with the name X-Frame-Options and the value DENY to prevent framing altogether, or the value SAMEORIGIN to allow framing only by pages on the same origin as the response itself. Note that the SAMEORIGIN header can be partially bypassed if the application itself can be made to frame untrusted websites.

• X-Frame-Options

• CWE-693: Protection Mechanism Failure

• /login
• /static/js/login.js

The presence of email addresses within application responses does not necessarily constitute a security vulnerability. Email addresses may appear intentionally within contact information, and many applications (such as web mail) include arbitrary third-party email addresses within their core content.

However, email addresses of developers and other individuals (whether appearing on-screen or hidden within page source) may disclose information that is useful to an attacker; for example, they may represent usernames that can be used at the application's login, and they may be used in social engineering attacks against the organization's personnel. Unnecessary or excessive disclosure of email addresses may also lead to an increase in the volume of spam email received.

Consider removing any email addresses that are unnecessary, or replacing personal addresses with anonymous mailbox addresses (such as helpdesk@example.com).

To reduce the quantity of spam sent to anonymous mailbox addresses, consider hiding the email address and instead providing a form that generates the email server-side, protected by a CAPTCHA if necessary.

• CWE-200: Information Exposure

• f65a581afccf448b882d686c5eee229c@o291828.ingest.sentry.io

• support@harbourshare.com

Unless directed otherwise, browsers may store a local cached copy of content received from web servers. Some browsers, including Internet Explorer, cache content accessed via HTTPS. If sensitive information in application responses is stored in the local cache, then this may be retrieved by other users who have access to the same computer at a future time.

Applications should return caching directives instructing browsers not to store local copies of any sensitive data. Often, this can be achieved by configuring the web server to prevent caching for relevant paths within the web root. Alternatively, most web development platforms allow you to control the server's caching directives from within individual scripts. Ideally, the web server should return the following HTTP headers in all responses containing sensitive content:

• Cache-control: no-store
• Pragma: no-cache

• CWE-524: Information Exposure Through Caching
• CWE-525: Information Exposure Through Browser Caching

Server certificate

Certificate chain #1

Certificate chain #2

Certificate chain #3

TLS (or SSL) helps to protect the confidentiality and integrity of information in transit between the browser and server, and to provide authentication of the server's identity. To serve this purpose, the server must present an TLS certificate that is valid for the server's hostname, is issued by a trusted authority and is valid for the current date. If any one of these requirements is not met, TLS connections to the server will not provide the full protection for which TLS is designed.

It should be noted that various attacks exist against TLS in general, and in the context of HTTPS web connections in particular. It may be possible for a determined and suitably-positioned attacker to compromise TLS connections without user detection even when a valid TLS certificate is used.

• SSL/TLS Configuration Guide

• CWE-295: Improper Certificate Validation
• CWE-326: Inadequate Encryption Strength
• CWE-327: Use of a Broken or Risky Cryptographic Algorithm