CVE-2008-2006 in iCal
Summary
by MITRE
Apple iCal 3.0.1 on Mac OS X allows remote CalDAV servers, and user-assisted remote attackers, to cause a denial of service (NULL pointer dereference and application crash) or possibly execute arbitrary code via a .ics file containing (1) a large 16-bit integer on a TRIGGER line, or (2) a large integer in a COUNT field on an RRULE line.
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Analysis
by VulDB Data Team • 06/01/2025
The vulnerability identified as CVE-2008-2006 represents a critical security flaw in Apple iCal 3.0.1 running on Mac OS X systems, which exposes users to potential remote exploitation through malicious CalDAV server interactions and user-assisted attack vectors. This issue stems from insufficient input validation within the calendar application's processing of iCalendar (.ics) files, creating a pathway for attackers to manipulate the application's behavior through carefully crafted calendar data. The vulnerability specifically targets the parsing mechanisms used to handle recurring calendar events and time-based triggers, making it particularly dangerous for users who regularly interact with calendar data from external sources or collaborative environments.
Technical analysis reveals that the flaw manifests through two distinct code paths within the iCal application's calendar data processing engine. The first vulnerability occurs when processing a TRIGGER line containing a large 16-bit integer value, which causes a NULL pointer dereference during the application's attempt to parse and validate the trigger timing information. The second vulnerability involves malformed COUNT field values within RRULE lines that contain excessively large integers, leading to similar memory corruption issues. Both scenarios result in the application crashing due to improper handling of integer overflow conditions and lack of proper boundary checks in the parsing routines. This vulnerability aligns with CWE-129, which addresses improper validation of array indices and integer overflows, and specifically demonstrates how unvalidated integer inputs can lead to memory corruption vulnerabilities.
The operational impact of this vulnerability extends beyond simple denial of service, as it potentially enables remote code execution in certain circumstances, making it a significant concern for enterprise environments and users who frequently access calendar data from external sources. Attackers can exploit this vulnerability by crafting malicious .ics files that, when opened by the vulnerable iCal application, trigger the memory corruption conditions leading to application crashes or potentially arbitrary code execution. The user-assisted nature of the attack means that victims must open the malicious calendar file, but this requirement is easily satisfied through social engineering tactics or automated calendar synchronization processes. Organizations using Apple iCal for calendar management and collaboration are particularly at risk, as the vulnerability can be exploited through legitimate calendar sharing and synchronization channels without requiring special privileges or network access.
Mitigation strategies for this vulnerability should include immediate application updates from Apple, as the company released patches to address the integer overflow conditions in the calendar parsing code. System administrators should implement strict calendar file validation policies, particularly for files received from external sources or untrusted collaborators, and consider deploying network-based intrusion detection systems to monitor for suspicious calendar data transfers. Additionally, users should be educated about the risks of opening calendar files from unknown sources and should verify the integrity of calendar data before importing it into their iCal applications. The vulnerability demonstrates the importance of input validation in calendar and scheduling applications, and aligns with ATT&CK technique T1203, which covers exploitation of remote services through malformed data inputs. Organizations should also consider implementing sandboxing mechanisms for calendar applications and establishing secure calendar sharing protocols to reduce the attack surface for such vulnerabilities.