CVE-2015-0235 in Communications Application Session Controller
Summary
by MITRE
Heap-based buffer overflow in the __nss_hostname_digits_dots function in glibc 2.2, and other 2.x versions before 2.18, allows context-dependent attackers to execute arbitrary code via vectors related to the (1) gethostbyname or (2) gethostbyname2 function, aka "GHOST."
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Analysis
by VulDB Data Team • 10/31/2024
The vulnerability identified as CVE-2015-0235 represents a critical heap-based buffer overflow in the GNU C Library implementation that affects systems running glibc versions 2.2 through 2.17. This flaw resides within the __nss_hostname_digits_dots function, which processes hostname resolution requests through the gethostbyname and gethostbyname2 system calls. The vulnerability has been widely known by the nickname "GHOST" due to its severe implications for network security and system integrity. The issue arises from improper bounds checking during hostname validation, creating a condition where malicious input can overwrite adjacent memory locations in the heap allocation. This particular flaw demonstrates the dangerous intersection of network service handling and memory management in system libraries, making it particularly attractive to attackers seeking persistent system compromise.
The technical exploitation of this vulnerability occurs when an attacker provides a specially crafted hostname string to functions that rely on the affected glibc components. The buffer overflow happens during the parsing of numeric hostnames containing dots, where the function fails to properly validate the length of input data against allocated buffer space. This allows attackers to overwrite heap metadata and potentially control program execution flow through arbitrary code execution. The vulnerability is context-dependent, meaning that exploitation typically requires the target application to make calls to gethostbyname or gethostbyname2 functions with malicious input. The flaw maps directly to CWE-121, which describes heap-based buffer overflow conditions, and demonstrates how improper memory management in core system libraries can create widespread security implications across numerous applications and services that depend on standard networking functions.
The operational impact of CVE-2015-0235 extends far beyond individual system compromise, as it affects any network service or application that relies on glibc for hostname resolution. Attackers can leverage this vulnerability to execute arbitrary code with the privileges of the affected process, potentially leading to complete system takeover or privilege escalation. The vulnerability affects a broad range of services including web servers, mail servers, database systems, and network applications that perform DNS lookups. Network-based exploitation is particularly concerning as it can occur without authentication, making the attack surface extremely wide. According to ATT&CK framework, this vulnerability maps to T1059 for command and scripting interpreter and T1068 for exploit for privilege escalation, highlighting the multi-stage attack potential. The impact is further amplified by the fact that many applications do not properly validate input before passing it to glibc functions, creating multiple potential attack vectors within the same system.
Mitigation strategies for CVE-2015-0235 require immediate patching of affected glibc versions to 2.18 or later, as this represents the most effective and permanent solution. System administrators should prioritize updating all affected systems, particularly those running network services that handle external hostname input. Additional defensive measures include implementing network segmentation to limit exposure, monitoring for unusual hostname resolution patterns, and configuring firewalls to restrict unnecessary DNS queries. Organizations should also consider implementing application-level input validation to reduce the likelihood of passing malicious data to vulnerable functions. The vulnerability underscores the importance of maintaining up-to-date system libraries and demonstrates how fundamental system components can become attack vectors when outdated. Security teams should conduct comprehensive vulnerability assessments to identify all systems running affected glibc versions and implement remediation plans accordingly. Regular security audits and patch management procedures should be strengthened to prevent similar vulnerabilities from remaining unaddressed for extended periods, as the window of exploitation for such critical flaws can be quite long.