CWE-204 响应差异性信息暴露

Response Discrepancy Information Exposure

结构: Simple

Abstraction: Base

状态: Incomplete

被利用可能性: unkown


The software provides different responses to incoming requests in a way that allows an actor to determine system state information that is outside of that actor's control sphere.


This issue frequently occurs during authentication, where a difference in failed-login messages could allow an attacker to determine if the username is valid or not. These exposures can be inadvertent (bug) or intentional (design).


  • cwe_Nature: ChildOf cwe_CWE_ID: 203 cwe_View_ID: 1000 cwe_Ordinal: Primary

  • cwe_Nature: ChildOf cwe_CWE_ID: 203 cwe_View_ID: 699 cwe_Ordinal: Primary


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


范围 影响 注释
['Confidentiality', 'Access Control'] ['Read Application Data', 'Bypass Protection Mechanism']


MIT-46 Architecture and Design

策略: Separation of Privilege

Compartmentalize the system to have "safe" areas where trust boundaries can be unambiguously drawn. Do not allow sensitive data to go outside of the trust boundary and always be careful when interfacing with a compartment outside of the safe area. Ensure that appropriate compartmentalization is built into the system design and that the compartmentalization serves to allow for and further reinforce privilege separation functionality. Architects and designers should rely on the principle of least privilege to decide when it is appropriate to use and to drop system privileges.

MIT-39 Implementation


Ensure that error messages only contain minimal details that are useful to the intended audience, and nobody else. The messages need to strike the balance between being too cryptic and not being cryptic enough. They should not necessarily reveal the methods that were used to determine the error. Such detailed information can be used to refine the original attack to increase the chances of success. If errors must be tracked in some detail, capture them in log messages - but consider what could occur if the log messages can be viewed by attackers. Avoid recording highly sensitive information such as passwords in any form. Avoid inconsistent messaging that might accidentally tip off an attacker about internal state, such as whether a username is valid or not.


The following code checks validity of the supplied username and password and notifies the user of a successful or failed login.

bad Perl

my $username=param('username');
my $password=param('password');

if (IsValidUsername($username) == 1)
if (IsValidPassword($username, $password) == 1)
print "Login Successful";
print "Login Failed - incorrect password";
print "Login Failed - unknown username";

In the above code, there are different messages for when an incorrect username is supplied, versus when the username is correct but the password is wrong. This difference enables a potential attacker to understand the state of the login function, and could allow an attacker to discover a valid username by trying different values until the incorrect password message is returned. In essence, this makes it easier for an attacker to obtain half of the necessary authentication credentials.

While this type of information may be helpful to a user, it is also useful to a potential attacker. In the above example, the message for both failed cases should be the same, such as:


"Login Failed - incorrect username or password"


标识 说明 链接
CVE-2002-2094 This, and others, use ".." attacks and monitor error responses, so there is overlap with directory traversal.
CVE-2001-1483 Enumeration of valid usernames based on inconsistent responses
CVE-2001-1528 Account number enumeration via inconsistent responses.
CVE-2004-2150 User enumeration via discrepancies in error messages.
CVE-2005-1650 User enumeration via discrepancies in error messages.
CVE-2004-0294 Bulletin Board displays different error messages when a user exists or not, which makes it easier for remote attackers to identify valid users and conduct a brute force password guessing attack.
CVE-2004-0243 Operating System, when direct remote login is disabled, displays a different message if the password is correct, which allows remote attackers to guess the password via brute force methods.
CVE-2002-0514 Product allows remote attackers to determine if a port is being filtered because the response packet TTL is different than the default TTL.
CVE-2002-0515 Product sets a different TTL when a port is being filtered than when it is not being filtered, which allows remote attackers to identify filtered ports by comparing TTLs.
CVE-2001-1387 Product may generate different responses than specified by the administrator, possibly leading to an information leak.
CVE-2004-0778 Version control system allows remote attackers to determine the existence of arbitrary files and directories via the -X command for an alternate history file, which causes different error messages to be returned.
CVE-2004-1428 FTP server generates an error message if the user name does not exist instead of prompting for a password, which allows remote attackers to determine valid usernames.



映射的分类名 ImNode ID Fit Mapped Node Name
PLOVER Response discrepancy infoleak