CVE-2011-0215 in Safari
Summary
by MITRE
ImageIO in Apple Safari before 5.0.6 on Windows does not properly address re-entrancy issues, which allows remote attackers to execute arbitrary code or cause a denial of service (application crash) via a crafted TIFF file.
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Analysis
by VulDB Data Team • 11/15/2021
The vulnerability identified as CVE-2011-0215 represents a critical re-entrancy flaw within Apple Safari's ImageIO framework on Windows platforms prior to version 5.0.6. This issue stems from inadequate handling of recursive function calls during image processing operations, specifically when processing TIFF file formats. The re-entrancy problem occurs when the ImageIO component receives a malformed TIFF image that triggers unexpected control flow patterns, potentially leading to memory corruption and unauthorized code execution. The vulnerability is particularly concerning because it operates at the image parsing layer where malicious actors can craft specially designed TIFF files to exploit this weakness. The flaw demonstrates a classic software security vulnerability where improper state management during recursive operations creates opportunities for attackers to manipulate program execution flow. According to CWE standards, this corresponds to CWE-367 which addresses Time-of-Check to Time-of-Use (TOCTOU) vulnerabilities and related re-entrancy issues that can lead to privilege escalation or arbitrary code execution.
The technical implementation of this vulnerability involves the ImageIO framework's handling of TIFF file structures where recursive parsing functions fail to properly validate or sanitize input data. When Safari encounters a crafted TIFF file with maliciously constructed data sequences, the recursive image parsing process can be manipulated to execute unintended code paths. The re-entrancy occurs because the framework does not adequately protect against recursive calls that could be triggered by specially crafted image metadata or compression parameters. Attackers can exploit this by creating TIFF files that contain recursive references or malformed structures designed to cause the parser to re-enter functions with malicious parameters. This creates a scenario where the application's memory management becomes compromised, potentially allowing attackers to overwrite critical program structures or execute arbitrary code within the browser's memory space. The vulnerability essentially allows for a form of heap-based buffer overflow or stack corruption when the recursive parsing logic encounters unexpected data patterns.
From an operational perspective, this vulnerability presents significant risk to users of affected Safari versions on Windows systems, as it enables remote code execution without requiring user interaction beyond visiting a malicious website or opening a compromised file. The attack surface is broad since TIFF files can be embedded in various web contexts or delivered through email attachments, making this vector particularly dangerous. The potential for denial of service represents a secondary impact where applications may crash or become unresponsive, disrupting user productivity and potentially enabling more sophisticated attacks. The vulnerability's impact extends beyond simple exploitation to include potential privilege escalation scenarios where attackers could gain elevated system privileges. Security researchers have noted that the timing and nature of the re-entrancy makes this particularly challenging to detect and prevent, as the malicious behavior occurs during legitimate image processing operations. The vulnerability's presence in the core image processing framework means that any web content or file that triggers TIFF parsing could potentially be exploited, creating a wide attack surface.
Mitigation strategies for CVE-2011-0215 primarily focus on updating to Safari version 5.0.6 or later, which includes proper re-entrancy handling and input validation mechanisms. System administrators should implement immediate patch management procedures to ensure all affected Windows systems receive the security updates. Additional protective measures include implementing content filtering solutions that can detect and block suspicious TIFF files, disabling automatic image loading in web browsers for untrusted sources, and employing network-based intrusion detection systems that monitor for exploitation attempts. Organizations should also consider implementing application whitelisting policies that restrict the execution of potentially vulnerable components. The remediation process should include thorough testing of the updated Safari versions to ensure compatibility with existing applications and workflows. Security teams should monitor for any reports of exploitation attempts and maintain updated threat intelligence feeds. According to ATT&CK framework, this vulnerability maps to techniques involving code injection and privilege escalation through application vulnerabilities, specifically targeting the browser's rendering engine and image processing capabilities. The vulnerability also aligns with techniques for initial access through malicious web content and execution through compromised applications, making it a multi-layered threat requiring comprehensive defensive measures across network, endpoint, and application security controls.