CWE-384 会话固定

Session Fixation

结构: Composite

Abstraction: Compound

状态: Incomplete

被利用可能性: unkown

基本描述

Authenticating a user, or otherwise establishing a new user session, without invalidating any existing session identifier gives an attacker the opportunity to steal authenticated sessions.

扩展描述

Such a scenario is commonly observed when:

相关缺陷

• cwe_Nature: ChildOf cwe_CWE_ID: 610 cwe_View_ID: 1000 cwe_Ordinal: Primary

• cwe_Nature: ChildOf cwe_CWE_ID: 610 cwe_View_ID: 1003 cwe_Ordinal: Primary

• cwe_Nature: ChildOf cwe_CWE_ID: 610 cwe_View_ID: 699

• cwe_Nature: Requires cwe_CWE_ID: 346 cwe_View_ID: 1000

• cwe_Nature: Requires cwe_CWE_ID: 472 cwe_View_ID: 1000

• cwe_Nature: Requires cwe_CWE_ID: 441 cwe_View_ID: 1000

适用平台

Language: {'cwe_Class': 'Language-Independent', 'cwe_Prevalence': 'Undetermined'}

常见的影响

可能的缓解方案

Architecture and Design

策略:

Invalidate any existing session identifiers prior to authorizing a new user session.

Architecture and Design

策略:

For platforms such as ASP that do not generate new values for sessionid cookies, utilize a secondary cookie. In this approach, set a secondary cookie on the user's browser to a random value and set a session variable to the same value. If the session variable and the cookie value ever don't match, invalidate the session, and force the user to log on again.

示例代码

例

The following example shows a snippet of code from a J2EE web application where the application authenticates users with LoginContext.login() without first calling HttpSession.invalidate().

bad Java

In order to exploit the code above, an attacker could first create a session (perhaps by logging into the application) from a public terminal, record the session identifier assigned by the application, and reset the browser to the login page. Next, a victim sits down at the same public terminal, notices the browser open to the login page of the site, and enters credentials to authenticate against the application. The code responsible for authenticating the victim continues to use the pre-existing session identifier, now the attacker simply uses the session identifier recorded earlier to access the victim's active session, providing nearly unrestricted access to the victim's account for the lifetime of the session. Even given a vulnerable application, the success of the specific attack described here is dependent on several factors working in the favor of the attacker: access to an unmonitored public terminal, the ability to keep the compromised session active and a victim interested in logging into the vulnerable application on the public terminal.

In most circumstances, the first two challenges are surmountable given a sufficient investment of time. Finding a victim who is both using a public terminal and interested in logging into the vulnerable application is possible as well, so long as the site is reasonably popular. The less well known the site is, the lower the odds of an interested victim using the public terminal and the lower the chance of success for the attack vector described above. The biggest challenge an attacker faces in exploiting session fixation vulnerabilities is inducing victims to authenticate against the vulnerable application using a session identifier known to the attacker.

In the example above, the attacker did this through a direct method that is not subtle and does not scale suitably for attacks involving less well-known web sites. However, do not be lulled into complacency; attackers have many tools in their belts that help bypass the limitations of this attack vector. The most common technique employed by attackers involves taking advantage of cross-site scripting or HTTP response splitting vulnerabilities in the target site [12]. By tricking the victim into submitting a malicious request to a vulnerable application that reflects JavaScript or other code back to the victim's browser, an attacker can create a cookie that will cause the victim to reuse a session identifier controlled by the attacker. It is worth noting that cookies are often tied to the top level domain associated with a given URL. If multiple applications reside on the same top level domain, such as bank.example.com and recipes.example.com, a vulnerability in one application can allow an attacker to set a cookie with a fixed session identifier that will be used in all interactions with any application on the domain example.com [29].

例

The following example shows a snippet of code from a J2EE web application where the application authenticates users with a direct post to the j_security_check, which typically does not invalidate the existing session before processing the login request.

bad HTML

Notes

分类映射

相关攻击模式

• CAPEC-196
• CAPEC-21
• CAPEC-31
• CAPEC-39
• CAPEC-59
• CAPEC-60
• CAPEC-61

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