CVE-2017-2582 in KeyCloak
Summary
by MITRE
It was found that while parsing the SAML messages the StaxParserUtil class of keycloak before 2.5.1 replaces special strings for obtaining attribute values with system property. This could allow an attacker to determine values of system properties at the attacked system by formatting the SAML request ID field to be the chosen system property which could be obtained in the "InResponseTo" field in the response.
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Analysis
by VulDB Data Team • 04/27/2023
The vulnerability identified as CVE-2017-2582 resides within the StaxParserUtil class of Keycloak versions prior to 2.5.1, representing a critical information disclosure flaw that exploits improper handling of SAML message parsing. This vulnerability manifests when the system processes SAML requests and attempts to parse attribute values, creating a dangerous condition where special strings are replaced with system property values during the parsing operation. The flaw specifically affects the processing of the SAML request ID field, which serves as a critical entry point for attackers seeking to extract sensitive system information.
The technical implementation of this vulnerability stems from the insecure replacement mechanism within the StaxParserUtil class, where the system blindly substitutes predefined special strings with actual system property values without proper sanitization or validation. When an attacker crafts a malicious SAML request with a specially formatted ID field that corresponds to a legitimate system property name, the parser executes the replacement operation and incorporates the system property value into the processing flow. This behavior occurs particularly within the "InResponseTo" field of the SAML response, where the system property values become exposed through the response structure, creating a direct information leakage channel.
The operational impact of this vulnerability extends beyond simple information disclosure, as it enables attackers to potentially extract sensitive system properties that could reveal critical infrastructure details, configuration parameters, or even authentication-related information. The vulnerability operates under the principle of information exposure through improper error handling, which aligns with CWE-209, and represents a form of insecure direct object reference that allows unauthorized access to system resources. Attackers can leverage this vulnerability to gather system properties such as java.home, user.dir, or other potentially sensitive runtime characteristics that could aid in further exploitation attempts or system reconnaissance activities.
This vulnerability also maps to ATT&CK technique T1082 - System Information Discovery, as it enables adversaries to collect system-level information that could be used for subsequent attacks. The flaw essentially creates a side-channel information leakage mechanism where system properties that should remain confidential become accessible through the SAML response processing. The impact is particularly severe because it requires minimal privileges to exploit, as the attacker only needs to craft a malicious SAML request that can be processed by the vulnerable Keycloak instance. The vulnerability demonstrates a classic case of inadequate input validation and improper handling of dynamic content, which can be categorized under CWE-20 - Improper Input Validation.
Mitigation strategies for CVE-2017-2582 focus primarily on upgrading to Keycloak version 2.5.1 or later, where the StaxParserUtil class has been modified to properly sanitize input before performing property replacements. Organizations should also implement additional security controls such as monitoring SAML request patterns for unusual ID field formatting and implementing rate limiting on authentication requests. Network-level protections including firewall rules that restrict access to SAML endpoints and intrusion detection systems that can identify suspicious SAML request patterns provide additional defense layers. Security teams should also conduct thorough code reviews of any custom SAML processing implementations and ensure proper input validation is implemented to prevent similar vulnerabilities from emerging in custom code deployments.