CVE-2015-2698 in Kerberos
Summary
by MITRE
The iakerb_gss_export_sec_context function in lib/gssapi/krb5/iakerb.c in MIT Kerberos 5 (aka krb5) 1.14 pre-release 2015-09-14 improperly accesses a certain pointer, which allows remote authenticated users to cause a denial of service (memory corruption) or possibly have unspecified other impact by interacting with an application that calls the gss_export_sec_context function. NOTE: this vulnerability exists because of an incorrect fix for CVE-2015-2696.
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Analysis
by VulDB Data Team • 06/27/2022
The vulnerability described in CVE-2015-2698 represents a critical memory corruption flaw within the MIT Kerberos 5 implementation that affects the iakerb_gss_export_sec_context function. This issue specifically manifests in the lib/gssapi/krb5/iakerb.c module and occurs in versions prior to the 2015-09-14 pre-release build. The vulnerability stems from improper pointer access patterns that create conditions where authenticated remote attackers can manipulate application behavior through interactions with systems utilizing the gss_export_sec_context function. The flaw essentially creates a scenario where memory corruption can occur, potentially leading to system instability or more severe consequences depending on the execution context. This vulnerability is particularly concerning because it leverages legitimate authentication mechanisms to exploit memory management issues within the Kerberos security framework.
The technical root cause of this vulnerability lies in the incorrect handling of pointer operations within the iakerb_gss_export_sec_context function, which is part of the Kerberos 5 implementation's Generic Security Services Application Program Interface. The flaw represents a classic case of improper pointer dereferencing or memory access violation that occurs when the function attempts to process security context exports. The vulnerability is particularly insidious because it was introduced as part of an incorrect fix for a previous vulnerability, CVE-2015-2696, demonstrating how remediation efforts can sometimes introduce new security weaknesses. This creates a dangerous precedent where security patches inadvertently create new attack vectors that can be exploited by authenticated users. The memory corruption that results from this improper pointer access can manifest in various ways including application crashes, memory leaks, or potentially more severe outcomes depending on the specific execution environment and memory layout.
The operational impact of this vulnerability extends beyond simple denial of service scenarios, as it can potentially enable more sophisticated attacks depending on the target system's configuration and execution environment. Remote authenticated users who can interact with applications that utilize the gss_export_sec_context function can trigger memory corruption that may lead to system instability, application crashes, or even potential privilege escalation in certain circumstances. The vulnerability affects systems that rely on Kerberos authentication mechanisms, which are widely deployed across enterprise environments, cloud infrastructure, and network services. Organizations using MIT Kerberos 5 versions prior to the fixed release are particularly at risk since the flaw allows for authenticated exploitation, meaning that attackers who have already gained some level of access to the system can leverage this weakness to cause more significant disruptions. The impact is amplified by the fact that many enterprise applications and services depend on Kerberos for authentication and authorization, making this vulnerability potentially widespread across multiple systems.
Mitigation strategies for CVE-2015-2698 should prioritize immediate patching of affected MIT Kerberos 5 implementations to the corrected version released after the 2015-09-14 pre-release. System administrators should conduct comprehensive inventory assessments to identify all systems running vulnerable versions of Kerberos and prioritize remediation efforts accordingly. The vulnerability's classification under CWE-476 indicates it involves a null pointer dereference or similar memory access issues, making it essential to implement proper input validation and pointer checking mechanisms. Organizations should also consider implementing network segmentation and access controls to limit the potential impact of authenticated attacks, as the vulnerability requires legitimate authentication to exploit. Monitoring and logging should be enhanced to detect unusual patterns of Kerberos authentication attempts that might indicate exploitation attempts. Additionally, following the ATT&CK framework's guidance for credential access and privilege escalation techniques, security teams should implement defensive measures against potential exploitation patterns that could leverage this vulnerability to gain further system access or escalate privileges within the authenticated session context.