CVE-2017-2947 in Acrobat Reader
Summary
by MITRE
Adobe Acrobat Reader versions 15.020.20042 and earlier, 15.006.30244 and earlier, 11.0.18 and earlier have a security bypass vulnerability when manipulating Form Data Format (FDF).
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Analysis
by VulDB Data Team • 10/28/2022
Adobe Acrobat Reader contains a security bypass vulnerability in its handling of Form Data Format files that affects multiple version ranges including 15.020.20042 and earlier, 15.006.30244 and earlier, and 11.0.18 and earlier. This vulnerability stems from insufficient validation of FDF files during the form data processing phase, allowing malicious actors to bypass intended security controls. The flaw specifically manifests when the application processes FDF files that contain crafted malicious content, potentially enabling unauthorized access to protected form fields or bypassing access restrictions. The vulnerability is categorized under CWE-284 Access Control Bypass, which describes weaknesses that allow unauthorized users to gain access to resources or functionality they should not be able to access. Attackers can exploit this issue by creating specially crafted FDF files that manipulate the form data processing logic, potentially leading to information disclosure or privilege escalation within the application's form handling environment. The security bypass occurs during the parsing and execution of FDF data structures, where the application fails to properly validate the integrity and authorization status of form fields. This weakness aligns with ATT&CK technique T1068, which involves exploiting vulnerabilities to gain local privileges, and T1555, which covers credential access through application vulnerabilities. The impact of this vulnerability extends beyond simple information disclosure, as it can enable attackers to manipulate form data in ways that should be restricted by access controls. When an unprivileged user opens a malicious FDF file, the application may incorrectly process the form data, allowing unauthorized modifications to protected fields or bypassing validation checks that should prevent such actions. The vulnerability represents a critical flaw in Adobe Reader's form processing engine and can be leveraged to undermine the security model of document-based applications that rely on form data integrity. Organizations using affected versions of Adobe Acrobat Reader should consider immediate remediation through patch updates, as the vulnerability provides attackers with a direct path to bypass application-level security controls. The flaw demonstrates the importance of proper input validation in document processing applications and highlights the risks associated with insufficient access control mechanisms in form data handling components. Security professionals should monitor for exploitation attempts targeting this vulnerability and ensure that all users are updated to versions that address the security bypass issue in FDF processing.
This vulnerability presents a significant risk to organizations that rely on Adobe Acrobat Reader for document processing, particularly in environments where form data contains sensitive information. The security bypass allows attackers to manipulate form fields in ways that should be restricted by access controls, potentially leading to unauthorized data access or modification. The FDF processing flaw occurs at the application layer where document parsing logic fails to properly validate the security context of form data elements, enabling malicious actors to craft FDF files that exploit this weakness. The vulnerability's classification as CWE-284 indicates that it represents a fundamental flaw in access control implementation, where the application fails to enforce proper authorization checks during form data manipulation. From an operational perspective, this vulnerability can be exploited through social engineering attacks where users are tricked into opening malicious FDF files, or through direct exploitation in environments where the application processes untrusted form data. The ATT&CK framework categorizes this vulnerability under techniques that involve privilege escalation and credential access through application vulnerabilities, making it particularly dangerous in enterprise environments. The risk is compounded by the widespread use of Adobe Acrobat Reader across organizations, meaning that a successful exploitation can affect numerous systems without requiring specialized knowledge of the target environment. Organizations should implement network monitoring to detect suspicious FDF file access patterns and ensure that all users maintain updated versions of the software to prevent exploitation. The vulnerability highlights the critical importance of validating form data integrity in document processing applications and demonstrates how seemingly minor flaws in input handling can lead to significant security consequences.
The technical implementation of this security bypass vulnerability occurs within Adobe Reader's form processing subsystem where FDF files are parsed and executed. When the application encounters an FDF file, it processes the form data structure without sufficient validation of the access control context, allowing maliciously crafted form elements to bypass intended restrictions. This flaw enables attackers to manipulate form fields in ways that should be prohibited by the application's access control mechanisms, potentially allowing unauthorized access to protected data or modification of form content. The vulnerability is particularly concerning because it affects multiple major version lines of Adobe Acrobat Reader, indicating a systemic issue in the form data processing implementation rather than a isolated bug. Security researchers have identified that the flaw exists in how the application handles the relationship between form field properties and access control permissions, where the validation logic fails to properly cross-reference field security attributes with the executing context. This bypass mechanism operates at the application layer and does not require elevated privileges to exploit, making it accessible to attackers with minimal technical expertise. The vulnerability's impact is amplified by the fact that FDF files are commonly used for form data exchange and can be embedded in various document formats, increasing the attack surface. Organizations should consider implementing application whitelisting policies to restrict FDF file processing and ensure that only trusted sources can provide form data to Adobe Reader applications. The security implications of this vulnerability extend to compliance requirements where organizations must maintain strict controls over sensitive data access, as this flaw could potentially violate data protection regulations. Effective mitigation requires not only patching the vulnerability but also implementing additional security controls such as sandboxing for document processing and network segmentation to limit the potential impact of exploitation attempts.