CVE-2008-4221 in Mac OS X
Summary
by MITRE
The strptime API in Libsystem in Apple Mac OS X before 10.5.6 allows context-dependent attackers to cause a denial of service (memory corruption and application crash) or execute arbitrary code via a crafted date string, related to improper memory allocation.
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Analysis
by VulDB Data Team • 08/22/2019
The vulnerability identified as CVE-2008-4221 affects the strptime application programming interface within Libsystem on Apple Mac OS X versions prior to 10.5.6. This flaw resides in the date parsing functionality that applications use to interpret and process date strings. The strptime function is a standard library routine designed to parse date and time information from character strings according to specified format patterns. When processing malformed or specially crafted date strings, the implementation fails to properly validate input parameters, leading to memory allocation issues that can result in system instability.
The technical nature of this vulnerability stems from improper memory allocation handling within the strptime function's internal implementation. Specifically, when the function encounters certain malformed date strings, it attempts to allocate memory without adequate bounds checking or input validation. This memory allocation flaw creates opportunities for attackers to manipulate the parsing process through carefully constructed input data. The vulnerability manifests as either memory corruption that leads to application crashes or more severe exploitation possibilities that could enable arbitrary code execution. The context-dependent nature of this vulnerability means that successful exploitation requires specific conditions and attacker control over the date string input being processed.
From an operational impact perspective, this vulnerability presents significant risks to Mac OS X systems running affected versions. Applications that utilize the strptime function for date parsing, including web browsers, email clients, system utilities, and custom software applications, become potential attack vectors. An attacker could craft malicious date strings that, when processed by vulnerable applications, would trigger the memory corruption or execution paths. This could lead to denial of service conditions where legitimate applications crash and become unavailable, or more dangerous scenarios where arbitrary code execution occurs, potentially allowing full system compromise. The vulnerability affects not just individual applications but could potentially impact system stability across multiple software components that rely on standard date parsing functionality.
The flaw aligns with CWE-122, which describes improper restriction of operations within a recognized security boundary, and represents a classic buffer overflow scenario that has been prevalent in system libraries. From an adversarial perspective, this vulnerability maps to several ATT&CK tactics including execution through valid accounts and privilege escalation via system-level vulnerabilities. The vulnerability's exploitation requires minimal prerequisites since it targets a fundamental system library function that most applications utilize. Security practitioners should note that this vulnerability represents a critical concern for organizations using older Mac OS X versions, as the memory corruption can be reliably triggered through crafted input that does not require elevated privileges. Remediation efforts should focus on updating to Mac OS X 10.5.6 or later versions where Apple has implemented proper input validation and memory allocation controls. Additionally, application developers should review their code for potential strptime usage and consider implementing additional input validation layers as defensive measures, particularly in applications that process untrusted date string inputs from external sources.