Cookie Security: Missing SameSite Attribute

The program fails to set the SameSite attribute on session cookies.

Browsers automatically append cookies to every HTTP request made to the site that sets the cookie. Cookies might store sensitive data such as session ID and authorization token or site data that is shared between different requests to the same site during a session. An attacker can perform an impersonation attack by generating a request to the authenticated site from a third-party site page loaded on the client machine because the browser automatically appends the cookie to the request.

The SameSite attribute limits the scope of the cookie such that it will only be attached to a request if the request is generated from first-party or same-site context. This helps to protect cookies from Cross-Site Request Forgery (CSRF) attacks. The SameSite attribute can have the following three values:

- Strict: When set to Strict, cookies are only sent along with requests upon top-level navigation.
- Lax: When set to Lax, cookies are sent with top-level navigation from the same host as well as GET requests originating from third-party sites, including those that have either iframe or href tags that link to the host site. If a user follows the link, the request will include the cookie.
- None: Cookies are sent in all requests made to the site within the path and domain scope set for the cookie. Requests generated due to form submissions using the POST method are also allowed to send cookies with request.

Example 1: The following code disables the SameSite attribute for session cookies.

    ...
    CookieOptions opt = new CookieOptions()
    {
        SameSite = SameSiteMode.None;
    };
    context.Response.Cookies.Append("name", "Foo", opt);
    ...

The program fails to set the SameSite attribute on session cookies.

Browsers automatically append cookies to every HTTP request made to the site that sets the cookie. Cookies might store sensitive data such as session ID and authorization token or site data that is shared between different requests to the same site during a session. An attacker can perform an impersonation attack by generating a request to the authenticated site from a third-party site page loaded on the client machine because the browser automatically appended the cookie to the request.

The SameSite attribute limits the scope of the cookie so that it is only attached to a request if the request is generated from first-party or same-site context. This helps to protect cookies from Cross-Site Request Forgery (CSRF) attacks. The SameSite attribute can have the following three values:

- Strict: When set to Strict, cookies are only sent along with requests upon top-level navigation.
- Lax: When set to Lax, cookies are sent with top-level navigation from the same host as well as GET requests originated to the host from third-party sites. For example, suppose a third-party site has either iframe or href tags that link to the host site. If a user follows the link, the request will include the cookie.
- None: Cookies are sent in all requests made to the site within the path and domain scope set for the cookie. Requests generated due to form submissions using the POST method are also allowed to send cookies with the request.

Example 1: The following code disables the SameSite attribute for session cookies.

c := &http.Cookie{
  Name: "cookie",
  Value: "samesite-none",
  SameSite: http.SameSiteNoneMode,
}

The program fails to set the SameSite attribute on session cookies.

Browsers automatically append cookies to every HTTP request made to the site that sets the cookie. Cookies might store sensitive data such as session ID and authorization token or site data that is shared between different requests to the same site during a session. An attacker can perform an impersonation attack by generating a request to the authenticated site from a third-party site page loaded on the client machine because the browser automatically appends the cookie to the request.

The SameSite attribute limits the scope of the cookie so that it is only attached to a request if the request is generated from first-party or same-site context. This helps to protect cookies from Cross-Site Request Forgery (CSRF) attacks. The SameSite attribute can have the following three values:

- Strict: When set to Strict, cookies are only sent along with requests upon top-level navigation.
- Lax: When set to Lax, cookies are sent with top-level navigation from the same host as well as GET requests originating from third-party sites, including those that have either iframe or href tags that link to the host site. For example, suppose there is a third-party site that has either iframe or href tags that link to the host site. If a user follows the link, the request will include the cookie.
- None: Cookies are sent in all requests made to the site within the path and domain scope set for the cookie. Requests generated due to form submissions using the POST method are also allowed to send cookies with the request.

Example 1: The following code disables the SameSite attribute for session cookies.

app.get('/', function (req, res) {
    ...
    res.cookie('name', 'Foo', { sameSite: false });
    ...
}

The program fails to set the SameSite attribute on session cookies.

Browsers automatically append cookies to every HTTP request made to the site that sets the cookie. Cookies might store sensitive data such as session ID and authorization token or site data that is shared between different requests to the same site during a session. An attacker can perform an impersonation attack by generating a request to the authenticated site from a third-party site page loaded on the client machine because the browser automatically appended the cookie to the request.

The SameSite attribute limits the scope of the cookie such that it will only be attached to a request if the request is generated from first-party or same-site context. This helps to protect cookies from Cross-Site Request Forgery (CSRF) attacks. The SameSite attribute can have the following three values:

- Strict: When set to Strict, cookies are only sent along with requests upon top-level navigation.
- Lax: When set to Lax, cookies are sent with top-level navigation from the same host as well as GET requests originated to the host from third-party sites. For example, suppose a third-party site has either iframe or href tags that link to the host site. If a user follows the link, the request will include the cookie.
- None: Cookies are sent in all requests made to the site within the path and domain scope set for the cookie. Requests generated due to form submissions using the POST method are also allowed to send cookies with request.

Example 1: The following code disables the SameSite attribute for session cookies.

session.cookie_samesite="None"

The program fails to set the SameSite attribute on session cookies.

Browsers automatically append cookies to every HTTP request made to the site that sets the cookie. Cookies might store sensitive data such as session ID and authorization token or site data that is shared between different requests to the same site during a session. An attacker can perform an impersonation attack by generating a request to the authenticated site from a third-party site page loaded on the client machine because the browser automatically appended the cookie to the request.

The samesite parameter limits the scope of the cookie so that it is only attached to a request if the request is generated from first-party or same-site context. This helps to protect cookies from Cross-Site Request Forgery (CSRF) attacks. The samesite parameter can have the following three values:

- Strict: When set to Strict, cookies are only sent along with requests upon top-level navigation.
- Lax: When set to Lax, cookies are sent with top-level navigation from the same host as well as GET requests originated to the host from third-party sites. For example, suppose a third-party site has either iframe or href tags that link to the host site. If a user follows the link, the request will include the cookie.
- None: Cookies are sent in all requests made to the site within the path and domain scope set for the cookie. Requests generated due to form submissions using the POST method are also allowed to send cookies with the request.

Example 1: The following code disables the SameSite attribute for session cookies.

  response.set_cookie("cookie", value="samesite-none", samesite=None)

A cookie was created without the SameSite attribute.

The SameSite attribute protects cookies from Cross-Site Request Forgery (CSRF) attacks. The browser automatically appends cookies to every HTTP request made to the site that sets the cookie. Cookies might store sensitive data like session ID and authorization token or site data that is shared between different requests to the same site during a session. An attacker can perform an impersonation attack by generating a request to the authenticated site from a third-party site page loaded on the client machine because the browser automatically appended the cookie to the request.
The SameSite attribute on a cookie allows sites to control that behaviour and prevents browsers from appending the cookie to request if the request is generated from a third-party site page load. The SameSite attribute can have the following three values:

- Strict: When set to Strict, cookies are only sent along with requests upon top level navigation.
- Lax: When set to Lax, cookies are sent with top level navigation from the same host as well as GET requests originated to the host from third-party sites (for example, in iframe, link, href, and so on and the form tag with GET method only).
- None: Cookies are sent in all requests made to the site within the path and domain scope set for the cookie. Requests generated due to form submissions using the POST method are also allowed to send cookies with request.
Please note that cookies that have the SameSite attribute with the value of None must be set with the Secure attribute otherwise the browser rejects the cookies. Additionally, a few specific browser versions reject the SameSite cookie with the None value for example, Chrome versions 51 to 66, versions of the UC Browser on Android prior to version 12.13.2, versions of Safari and embedded browsers on macOS 10.14, and all browsers on iOS 12 reject cookies set with SameSite=None. A suggested workaround for this issue is to set an alternate cookie with a prefix or suffix such as Legacy appended to cookiename. Sites can look for this legacy cookie if it does not find a cookie that was set with SameSite=None.