CVE-2014-3198 in Chrome
Summary
by MITRE
The Instance::HandleInputEvent function in pdf/instance.cc in the PDFium component in Google Chrome before 38.0.2125.101 interprets a certain -1 value as an index instead of a no-visible-page error code, which allows remote attackers to cause a denial of service (out-of-bounds read) via unspecified vectors.
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Analysis
by VulDB Data Team • 02/21/2022
The vulnerability identified as CVE-2014-3198 resides within the PDFium component of Google Chrome, specifically in the Instance::HandleInputEvent function located in pdf/instance.cc. This flaw represents a classic buffer over-read condition that occurs when the system fails to properly validate input parameters before processing them. The issue manifests when a particular -1 value intended as an error code indicating no visible page is incorrectly interpreted as a valid index value, creating a scenario where the application attempts to access memory locations beyond the intended bounds.
The technical implementation of this vulnerability stems from improper input validation within the PDF rendering engine's event handling mechanism. When processing PDF input events, the system should distinguish between legitimate index values and error codes that indicate exceptional conditions. However, the flaw allows the -1 error code, which should signal that no visible page exists, to be treated as a valid array index. This misinterpretation leads to an out-of-bounds memory read operation, where the application attempts to access memory locations that are not allocated for the current page context, resulting in unpredictable behavior and potential system instability.
From an operational perspective, this vulnerability enables remote attackers to execute denial of service attacks against Chrome users without requiring any special privileges or user interaction. The attack vector is particularly concerning because it can be triggered through malformed PDF documents delivered via web pages, email attachments, or other means of PDF content delivery. The out-of-bounds read condition can cause the browser to crash or exhibit erratic behavior, effectively rendering the application unusable for the affected user. This type of vulnerability directly impacts the availability and reliability of the browser component, making it a significant concern for enterprise environments where browser stability is critical.
The vulnerability aligns with CWE-129, which describes improper validation of array indices, and can be categorized under the ATT&CK technique T1203, which involves exploiting input validation flaws to cause system instability. The impact extends beyond simple denial of service to potentially exposing underlying memory structures that could be leveraged in more sophisticated attacks. Security practitioners should note that this vulnerability represents a common class of flaws in complex software systems where input validation is insufficient to handle exceptional conditions properly. The fix implemented in Chrome 38.0.2125.101 involved proper validation of the -1 value to ensure it is recognized as an error code rather than an array index, demonstrating the importance of robust input validation in preventing such memory safety issues.
Organizations should prioritize patching this vulnerability as part of their regular security maintenance procedures, particularly given the remote attack surface and potential for exploitation in targeted campaigns. The vulnerability serves as a reminder of the critical importance of memory safety considerations in PDF rendering engines and other complex document processing components. Additionally, implementing additional security measures such as sandboxing, input validation, and regular security assessments can help mitigate similar vulnerabilities that may exist in other components of the browser ecosystem. The incident highlights the necessity of comprehensive testing procedures, including fuzzing and boundary condition testing, to identify such subtle but impactful flaws in software components that handle user-provided data.