CVE-2010-4754 in FreeBSD
Summary
by MITRE
The glob implementation in libc in FreeBSD 7.3 and 8.1, NetBSD 5.0.2, and OpenBSD 4.7, and Libsystem in Apple Mac OS X before 10.6.8, allows remote authenticated users to cause a denial of service (CPU and memory consumption) via crafted glob expressions that do not match any pathnames, as demonstrated by glob expressions in STAT commands to an FTP daemon, a different vulnerability than CVE-2010-2632.
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Analysis
by VulDB Data Team • 02/09/2019
The vulnerability described in CVE-2010-4754 represents a critical flaw in glob pattern processing implementations across multiple operating systems including FreeBSD, NetBSD, OpenBSD, and Apple Mac OS X. This issue specifically targets the glob function implementation within libc and libsystem libraries, which are fundamental components responsible for pathname expansion and pattern matching operations. The vulnerability manifests when these systems process crafted glob expressions that do not match any existing pathnames, leading to excessive resource consumption that can ultimately result in system denial of service conditions.
The technical flaw resides in the inefficient handling of non-matching glob patterns within the underlying glob implementation. When a glob expression is processed and fails to match any existing pathnames, the implementation enters into a computationally expensive loop or recursive operation that consumes disproportionate amounts of CPU cycles and memory resources. This behavior occurs regardless of the complexity of the glob pattern itself, making it particularly dangerous as attackers can craft simple expressions that still trigger the resource exhaustion. The vulnerability is particularly severe because it affects core system libraries that are extensively used throughout the operating system and network services, including FTP daemons that process user-supplied glob patterns during STAT commands.
The operational impact of this vulnerability extends beyond simple denial of service conditions to potentially compromise system availability and stability. Network services such as FTP daemons that utilize glob pattern matching for file listing operations become particularly vulnerable, as attackers can authenticate to the service and submit malicious glob expressions that trigger the resource consumption behavior. The vulnerability demonstrates a classic example of a resource exhaustion attack that can be executed remotely by authenticated users, making it particularly dangerous in multi-user environments where service availability is critical. System administrators may observe gradual performance degradation followed by complete service unavailability as the malicious glob patterns cause the system to consume all available CPU and memory resources.
This vulnerability aligns with CWE-400, which categorizes resource exhaustion flaws in software implementations, and represents a specific instance of improper input validation where the system fails to properly handle edge cases in glob pattern processing. From an ATT&CK framework perspective, this vulnerability maps to T1499.004, which covers network denial of service attacks, and T1059, which covers command and scripting interpreter execution. The exploitation requires minimal privileges since only authenticated access is needed, making it particularly attractive to attackers seeking to disrupt services without requiring elevated system permissions. Organizations should implement immediate mitigations including applying vendor-specific patches, implementing rate limiting on glob pattern processing, and monitoring for unusual resource consumption patterns that may indicate exploitation attempts.
The root cause analysis reveals that the glob implementation lacks proper bounds checking and resource allocation limits when processing non-matching patterns. This deficiency allows the pattern matching engine to enter infinite or extremely long-running loops without proper safeguards against excessive resource consumption. The vulnerability demonstrates the importance of proper input validation and resource management in system libraries, particularly those that handle user-supplied data in pattern matching operations. Security practitioners should consider implementing defensive programming practices such as maximum iteration limits, memory usage monitoring, and timeout mechanisms to prevent similar issues in other pattern matching implementations. The vulnerability also highlights the need for comprehensive testing of edge cases in system libraries, particularly those handling complex pattern matching operations that are commonly used in network services and file system operations.
Organizations affected by this vulnerability should prioritize patch management and system updates to address the specific implementations in their operating systems. The remediation process should include verifying that all affected systems have received appropriate security updates from their respective vendors, including FreeBSD, NetBSD, OpenBSD, and Apple. Additionally, implementing network-level controls such as firewalls and intrusion detection systems can help detect and prevent exploitation attempts by monitoring for suspicious glob pattern usage in network protocols. Regular security assessments should include testing for similar vulnerabilities in other system libraries and applications that perform pattern matching operations to ensure comprehensive protection against resource exhaustion attacks.