CVE-2015-7547 in Fujitsu M10-1
Summary
by MITRE
Multiple stack-based buffer overflows in the (1) send_dg and (2) send_vc functions in the libresolv library in the GNU C Library (aka glibc or libc6) before 2.23 allow remote attackers to cause a denial of service (crash) or possibly execute arbitrary code via a crafted DNS response that triggers a call to the getaddrinfo function with the AF_UNSPEC or AF_INET6 address family, related to performing "dual A/AAAA DNS queries" and the libnss_dns.so.2 NSS module.
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Analysis
by VulDB Data Team • 01/27/2025
The vulnerability identified as CVE-2015-7547 represents a critical stack-based buffer overflow within the GNU C Library's libresolv component, specifically affecting the send_dg and send_vc functions. This flaw exists in glibc versions prior to 2.23 and manifests when processing DNS responses that trigger the getaddrinfo function with AF_UNSPEC or AF_INET6 address families. The vulnerability is particularly dangerous because it enables remote attackers to exploit the system through crafted DNS responses, potentially leading to either denial of service or arbitrary code execution. The issue stems from improper handling of DNS query results during dual A/AAAA DNS queries, where the libnss_dns.so.2 NSS module fails to properly validate buffer boundaries when processing response data. This vulnerability is classified under CWE-121 as a stack-based buffer overflow, which occurs when more data is written to a buffer than it can hold, leading to memory corruption that can be exploited to overwrite adjacent memory locations.
The operational impact of CVE-2015-7547 extends beyond simple service disruption, as it can potentially enable remote code execution on affected systems. When a vulnerable application makes a DNS lookup using getaddrinfo with AF_UNSPEC or AF_INET6, the libresolv library processes the DNS response and attempts to store the results in a buffer on the stack. If the DNS response contains maliciously crafted data that exceeds the buffer size, the overflow can overwrite critical memory segments including return addresses, function pointers, or other control data. This memory corruption can cause the application to crash or potentially allow an attacker to execute arbitrary code with the privileges of the affected process. The vulnerability is particularly concerning because getaddrinfo is a widely used function in network applications, making numerous services susceptible to exploitation. Attackers can craft DNS responses that trigger the vulnerable code path, potentially leading to complete system compromise, especially when targeting critical infrastructure components or applications that perform DNS resolution without proper input validation.
The exploitation of this vulnerability aligns with several techniques described in the MITRE ATT&CK framework, particularly those related to privilege escalation and code execution through memory corruption vulnerabilities. The attack surface includes any application or service that relies on glibc's DNS resolution capabilities, including web servers, email servers, and network applications that perform hostname resolution. The vulnerability demonstrates the importance of proper input validation and buffer management in system libraries, as the flaw exists at a fundamental level within the core networking libraries that most applications depend upon. Organizations running vulnerable versions of glibc are at significant risk because the exploitation requires minimal privileges and can be accomplished through standard DNS traffic manipulation. The vulnerability also highlights the critical nature of keeping system libraries updated, as many applications are built against glibc and inherit these security flaws without requiring code modifications. Security practitioners should note that this vulnerability is not limited to specific applications but affects the entire operating system ecosystem that depends on the GNU C Library for network operations, making it a high-priority remediation target.
Mitigation strategies for CVE-2015-7547 primarily focus on updating to glibc version 2.23 or later, which contains the necessary patches to address the buffer overflow conditions. System administrators should also consider implementing DNS sinkholing or filtering mechanisms to prevent malicious DNS responses from reaching vulnerable applications. Network-level protections such as DNS query filtering and monitoring for unusual DNS traffic patterns can help detect potential exploitation attempts. Additionally, applications can be hardened by implementing proper input validation for DNS responses and using stack protection mechanisms. The vulnerability underscores the importance of maintaining up-to-date system libraries and implementing comprehensive security monitoring to detect and respond to exploitation attempts. Organizations should also conduct thorough vulnerability assessments to identify all systems running affected glibc versions and prioritize remediation efforts accordingly. Regular security audits and patch management processes are essential to prevent similar vulnerabilities from being exploited in the future, particularly given the widespread use of glibc across Unix-like operating systems and the critical role it plays in network operations.