CVE-2023-34339 in Ktor
Summary
by MITRE • 06/01/2023
In JetBrains Ktor before 2.3.1 headers containing authentication data could be added to the exception's message
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Analysis
by VulDB Data Team • 06/02/2023
The vulnerability identified as CVE-2023-34339 affects JetBrains Ktor versions prior to 2.3.1 and represents a critical information disclosure flaw that can potentially expose sensitive authentication data within exception messages. This vulnerability arises from improper handling of HTTP headers during exception processing within the Ktor framework, creating a scenario where authentication-related information may be inadvertently included in error messages that are subsequently exposed to unauthorized parties. The flaw demonstrates a clear failure in secure error handling practices and data sanitization mechanisms.
The technical implementation of this vulnerability stems from the framework's lack of proper header filtering when constructing exception messages. When Ktor encounters an error condition during HTTP request processing, it may include HTTP headers from the request in the exception's error message output. If these headers contain authentication tokens, session identifiers, or other sensitive credentials, they become exposed to anyone who can access the error message, whether through direct logging, debugging interfaces, or network monitoring tools. This behavior violates fundamental security principles of information hiding and access control, as it provides attackers with potential avenues to extract authentication data from the application's error reporting mechanisms.
The operational impact of this vulnerability extends beyond simple information disclosure, as it can enable attackers to escalate privileges and gain unauthorized access to protected resources. When authentication data is included in exception messages, it can be leveraged by malicious actors to impersonate legitimate users, bypass authentication mechanisms, or conduct session hijacking attacks. The vulnerability is particularly concerning in environments where detailed error messages are logged or displayed to users, as it can provide attackers with the exact credentials needed to compromise user accounts or system resources. This flaw directly aligns with CWE-209, which addresses the improper handling of exceptions and error conditions that can lead to information disclosure.
Organizations utilizing JetBrains Ktor frameworks prior to version 2.3.1 face significant security risks from this vulnerability, as it can be exploited through various attack vectors including web application scanning tools, manual penetration testing, or automated exploit frameworks. The attack surface is broad since any application using Ktor that processes HTTP requests and encounters errors could potentially expose authentication data in exception messages. This vulnerability also maps to ATT&CK technique T1211, which involves the exploitation of information disclosure vulnerabilities to gain access to credentials and sensitive information. The risk is exacerbated in cloud environments where error logging may be shared across multiple systems or exposed through monitoring services.
The recommended mitigation strategy involves upgrading to JetBrains Ktor version 2.3.1 or later, which includes proper header sanitization and filtering mechanisms to prevent authentication data from being included in exception messages. Organizations should also implement comprehensive logging controls that sanitize error messages before they are stored or transmitted, and ensure that authentication headers are explicitly excluded from error reporting. Additional defensive measures include implementing proper input validation, configuring secure error handling procedures, and conducting regular security assessments to identify similar vulnerabilities in the application stack. The fix addresses the root cause by implementing strict header filtering during exception message construction, preventing the accidental exposure of sensitive information through error reporting mechanisms.