CVE-2011-3261 in iOS
Summary
by MITRE
Double free vulnerability in OfficeImport in Apple iOS before 5 allows remote attackers to execute arbitrary code or cause a denial of service (application crash) via a crafted Excel spreadsheet.
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Analysis
by VulDB Data Team • 11/24/2021
The CVE-2011-3261 vulnerability represents a critical double free memory corruption flaw within Apple iOS's OfficeImport component, which processes various office document formats including Excel spreadsheets. This vulnerability exists in iOS versions prior to 5.0, making it particularly dangerous as it affects a substantial user base of mobile devices running older iOS versions. The flaw manifests when the OfficeImport framework improperly handles memory allocation and deallocation during the parsing of maliciously crafted Excel files, creating conditions where the same memory block can be freed twice, leading to unpredictable behavior and potential code execution.
The technical nature of this vulnerability aligns with CWE-415, which describes improper double free conditions in memory management. When an attacker crafts a specially designed Excel spreadsheet containing malformed data structures, the OfficeImport component processes this data without adequate validation, causing the memory management routines to attempt freeing the same memory address twice. This double free condition can be exploited to overwrite critical memory locations, potentially allowing attackers to manipulate program execution flow and execute arbitrary code with the privileges of the affected application. The vulnerability specifically impacts the iOS OfficeImport framework that handles Microsoft Office document formats, making it particularly relevant for mobile security assessments.
The operational impact of this vulnerability extends beyond simple denial of service, as it provides remote attackers with a pathway for arbitrary code execution on affected iOS devices. An attacker could deliver a malicious Excel file through various vectors including email attachments, web downloads, or malicious websites, without requiring user interaction beyond opening the file. The vulnerability enables attackers to escalate privileges and potentially gain full control over the device, making it a significant threat to mobile device security. This type of vulnerability is particularly concerning in enterprise environments where iOS devices handle sensitive corporate data and where attackers may leverage the exploit for data exfiltration or further network infiltration.
Organizations and individuals should immediately update to iOS 5.0 or later to remediate this vulnerability, as no reliable workarounds exist for the affected versions. The exploit requires no special privileges or user interaction beyond opening the malicious file, making it particularly dangerous in targeted attack scenarios. Security teams should monitor for indicators of compromise related to this vulnerability, including unusual network traffic patterns or attempts to access vulnerable iOS versions. This vulnerability demonstrates the importance of timely patch management and proper input validation in mobile operating systems, aligning with ATT&CK technique T1059 for command and scripting interpreter usage and T1133 for external remote services for maintaining access. Organizations should implement network-based detection measures to identify attempts to deliver malicious Excel files and maintain comprehensive backup and recovery procedures to mitigate potential exploitation consequences.