CVE-2011-3113 in Chrome
Summary
by MITRE
The PDF functionality in Google Chrome before 19.0.1084.52 does not properly perform a cast of an unspecified variable during handling of color spaces, which allows remote attackers to cause a denial of service or possibly have unknown other impact via a crafted document.
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Analysis
by VulDB Data Team • 03/25/2021
The vulnerability identified as CVE-2011-3113 represents a critical flaw in Google Chrome's PDF rendering engine that existed prior to version 19.0.1084.52. This issue manifests within the browser's handling of color space conversions during PDF document processing, specifically involving an improper type casting operation that occurs when Chrome attempts to interpret color information within PDF files. The flaw affects the chromium-based browser's embedded PDF viewer component, which is responsible for displaying PDF documents without requiring external plugins. The vulnerability resides in the PDFium library, which is the core PDF rendering engine used by Chrome and other Google products. This type of memory corruption issue typically arises when the software fails to properly validate or convert data types during processing operations, creating potential entry points for malicious actors.
The technical nature of this vulnerability stems from an unspecified variable casting operation that occurs within the color space handling logic of Chrome's PDF parser. When processing PDF documents containing specially crafted color space definitions, the browser's rendering engine encounters a scenario where it attempts to cast a variable to an inappropriate type, leading to memory corruption. This improper casting can result in unpredictable behavior within the application's memory management system, potentially causing the browser to crash or behave erratically. The vulnerability is particularly concerning because it operates at the level of the PDF rendering engine, which is invoked whenever users open PDF documents in Chrome. The flaw demonstrates characteristics consistent with a buffer overflow or type confusion vulnerability, where the application fails to properly validate data types before processing them, leading to potential exploitation scenarios.
The operational impact of CVE-2011-3113 extends beyond simple denial of service conditions to potentially enable more sophisticated attacks. Remote attackers can craft malicious PDF documents that, when opened in vulnerable Chrome versions, trigger the memory corruption issue. While the primary reported impact is denial of service through browser crashes, the unspecified nature of the potential secondary effects suggests that this vulnerability could theoretically be exploited for more advanced attack vectors. The vulnerability affects users who browse the internet and open PDF documents, making it particularly dangerous in environments where users encounter untrusted content. The attack surface is broad since PDF files are commonly distributed through email attachments, web downloads, and various online platforms. This vulnerability aligns with CWE-129, which covers improper validation of array indices, and could potentially map to ATT&CK technique T1203, involving exploitation of web browsers for privilege escalation. The risk is elevated because users may inadvertently open malicious PDF files without recognizing the threat, especially when the files appear legitimate.
Mitigation strategies for CVE-2011-3113 primarily focus on updating to patched versions of Google Chrome where the vulnerability has been resolved. Users should immediately upgrade to Chrome version 19.0.1084.52 or later, which includes fixes for the PDF rendering engine's color space handling logic. Organizations should implement automated update policies to ensure all Chrome installations remain current with security patches. Additional protective measures include configuring web browsers to disable automatic PDF viewing or to prompt users before opening PDF files, particularly when they originate from untrusted sources. Network administrators can deploy content filtering solutions that scan PDF files for suspicious patterns before allowing them to reach end users. Security-conscious organizations should consider implementing sandboxing mechanisms that isolate PDF processing from the main browser environment. The vulnerability highlights the importance of keeping browser software updated, as it represents a classic example of how PDF rendering engines can become attack vectors when they fail to properly validate input data. The fix implemented by Google likely involved strengthening type validation checks and ensuring proper casting operations during color space processing within the PDF parser component.