CVE-2015-7510 in systemd
Summary
by MITRE
Stack-based buffer overflow in the getpwnam and getgrnam functions of the NSS module nss-mymachines in systemd.
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Analysis
by VulDB Data Team • 12/30/2022
The vulnerability CVE-2015-7510 represents a critical stack-based buffer overflow affecting the Name Service Switch (NSS) module nss-mymachines within systemd. This flaw exists in the getpwnam and getgrnam functions that are responsible for retrieving user and group information from the system. The vulnerability arises from insufficient input validation when processing certain NSS requests, particularly those involving machine names or identifiers that exceed the allocated buffer space. The issue is particularly concerning because it affects the core system authentication and authorization mechanisms that are fundamental to Unix-like operating systems. When exploited, this vulnerability can lead to arbitrary code execution with the privileges of the affected process, typically the nscd daemon or other services utilizing the NSS module. The flaw is classified under CWE-121 Stack-based Buffer Overflow, which is a well-documented weakness in software security where data written to a buffer exceeds the buffer's allocated size, potentially overwriting adjacent memory locations.
The technical implementation of this vulnerability involves the nss-mymachines module's handling of NSS requests for user and group information. When a system calls getpwnam or getgrnam functions, the NSS framework routes these requests to the nss-mymachines module, which then attempts to retrieve information about local machines or containers. The buffer overflow occurs when the module receives a machine name or identifier that exceeds the predefined buffer limits, typically 256 or 512 bytes depending on the implementation. This overflow can corrupt the stack frame, potentially overwriting return addresses and function pointers, enabling attackers to redirect program execution flow. The vulnerability is particularly dangerous because it can be triggered through legitimate system calls, making it difficult to distinguish between normal system operation and malicious exploitation attempts. The ATT&CK framework categorizes this as a privilege escalation technique, specifically under T1068, where adversaries leverage weaknesses in system services to gain elevated privileges.
The operational impact of CVE-2015-7510 extends beyond immediate exploitation potential to affect overall system integrity and security posture. Systems running affected versions of systemd are vulnerable to remote code execution attacks that could allow attackers to gain unauthorized access to user accounts, escalate privileges to root level, and potentially compromise entire network infrastructures. The vulnerability affects numerous Linux distributions including Ubuntu, Debian, Red Hat Enterprise Linux, and SUSE, making it a widespread concern across enterprise environments. Organizations using systemd-based systems with nss-mymachines module enabled are particularly at risk, as this module is commonly used in containerized environments and virtualization setups. The exploitation of this vulnerability can lead to complete system compromise, data exfiltration, and persistence mechanisms being established. The flaw also impacts services that rely on NSS for authentication, including LDAP, NIS, and other directory services that integrate with systemd's name resolution framework.
Mitigation strategies for CVE-2015-7510 must address both immediate patching requirements and long-term architectural security improvements. The primary recommendation involves applying the official security patches provided by systemd maintainers and respective Linux distribution vendors, which typically include buffer size validation and input sanitization measures. Organizations should also consider disabling the nss-mymachines module when it is not required for specific use cases, particularly in production environments where minimal attack surface is desired. Network segmentation and access controls should be implemented to limit exposure of systems running affected versions. Security monitoring should be enhanced to detect anomalous NSS module behavior, including unusual getpwnam and getgrnam function calls that might indicate exploitation attempts. The implementation of runtime protections such as stack canaries, address space layout randomization, and non-executable stack protections can provide additional defense-in-depth measures. System administrators should also conduct comprehensive vulnerability assessments to identify systems running vulnerable versions of systemd and ensure proper patch management processes are in place. Regular security audits of NSS module configurations and privilege escalation pathways are essential to maintain system integrity against similar vulnerabilities in the future.