CWE-209 Generation of Error Message Containing Sensitive Information

The product generates an error message that includes sensitive information about its environment, users, or associated data.

• Confidentiality: Read Application Data — Often this will either reveal sensitive information which may be used to launch another, more focused attack or disclose private information stored in the server. For example, an attempt to exploit a path traversal weakness (CWE-22) might yield the full pathname of the installed application. In turn, this could be used to select the proper number of ".." sequences to navigate to the targeted file. An attack using SQL injection (CWE-89) might not initially succeed, but an error message could reveal the malformed query, which would expose query logic and possibly even passwords or other sensitive information used within the query.

• [Implementation] Ensure that error messages only contain minimal details that are useful to the intended audience and no one else. The messages need to strike the balance between being too cryptic (which can confuse users) or being too detailed (which may reveal more than intended). The messages should not reveal the methods that were used to determine the error. Attackers can use detailed information to refine or optimize their original attack, thereby increasing their chances of success. If errors must be captured in some detail, record them in log messages, but consider what could occur if the log messages can be viewed by attackers. Highly sensitive information such as passwords should never be saved to log files. Avoid inconsistent messaging that might accidentally tip off an attacker about internal state, such as whether a user account exists or not. • [Implementation] Handle exceptions internally and do not display errors containing potentially sensitive information to a user. • [Implementation] Use naming conventions and strong types to make it easier to spot when sensitive data is being used. When creating structures, objects, or other complex entities, separate the sensitive and non-sensitive data as much as possible. • [Implementation, Build and Compilation] Debugging information should not make its way into a production release. • [Implementation, Build and Compilation] Debugging information should not make its way into a production release. • [System Configuration] Where available, configure the environment to use less verbose error messages. For example, in PHP, disable the display_errors setting during configuration, or at runtime using the error_reporting() function. • [System Configuration] Create default error pages or messages that do not leak any information.

• Manual Analysis: This weakness generally requires domain-specific interpretation using manual analysis. However, the number of potential error conditions may be too large to cover completely within limited time constraints. • Automated Analysis: Automated methods may be able to detect certain idioms automatically, such as exposed stack traces or pathnames, but violation of business rules or privacy requirements is not typically feasible. • Automated Dynamic Analysis: This weakness can be detected using dynamic tools and techniques that interact with the software using large test suites with many diverse inputs, such as fuzz testing (fuzzing), robustness testing, and fault injection. The software's operation may slow down, but it should not become unstable, crash, or generate incorrect results. Error conditions may be triggered with a stress-test by calling the software simultaneously from a large number of threads or processes, and look for evidence of any unexpected behavior. • Manual Dynamic Analysis: Identify error conditions that are not likely to occur during normal usage and trigger them. For example, run the program under low memory conditions, run with insufficient privileges or permissions, interrupt a transaction before it is completed, or disable connectivity to basic network services such as DNS. Monitor the software for any unexpected behavior. If you trigger an unhandled exception or similar error that was discovered and handled by the application's environment, it may still indicate unexpected conditions that were not handled by the application itself. • Automated Static Analysis: Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)

• CVE-2008-2049: POP3 server reveals a password in an error message after multiple APOP commands are sent. Might be resultant from another weakness. • CVE-2007-5172: Program reveals password in error message if attacker can trigger certain database errors. • CVE-2008-4638: Composite: application running with high privileges (CWE-250) allows user to specify a restricted file to process, which generates a parsing error that leaks the contents of the file (CWE-209). • CVE-2008-1579: Existence of user names can be determined by requesting a nonexistent blog and reading the error message. • CVE-2007-1409: Direct request to library file in web application triggers pathname leak in error message. • CVE-2008-3060: Malformed input to login page causes leak of full path when IMAP call fails. • CVE-2005-0603: Malformed regexp syntax leads to information exposure in error message. • CVE-2017-9615: verbose logging stores admin credentials in a world-readable log file • CVE-2018-1999036: SSH password for private key stored in build log