CVE-2017-9083 in Poppler
Summary
by MITRE
poppler 0.54.0, as used in Evince and other products, has a NULL pointer dereference in the JPXStream::readUByte function in JPXStream.cc. For example, the perf_test utility will crash (segmentation fault) when parsing an invalid PDF file.
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Analysis
by VulDB Data Team • 12/06/2022
The vulnerability identified as CVE-2017-9083 represents a critical NULL pointer dereference flaw within the poppler library version 0.54.0, which is extensively utilized by desktop applications including the popular Evince document viewer. This issue manifests specifically within the JPXStream::readUByte function located in the JPXStream.cc source file, demonstrating how improper input validation can lead to severe system instability. The flaw occurs when processing malformed or invalid PDF files, particularly those containing JPEG2000 encoded data streams that are not properly handled by the library's parsing mechanisms. The vulnerability affects not only Evince but also any software products that incorporate the vulnerable poppler library version, creating a widespread potential impact across numerous desktop environments and document processing applications.
The technical nature of this vulnerability stems from the absence of proper null pointer checks within the JPXStream::readUByte function, which is responsible for reading unsigned byte values from JPEG2000 streams within PDF documents. When the parser encounters an invalid PDF file structure, particularly one with malformed JPEG2000 data segments, the function attempts to dereference a null pointer that was not properly initialized or validated. This condition typically arises during the parsing of corrupted or maliciously crafted PDF files that contain unexpected data structures, causing the application to crash with a segmentation fault. The vulnerability is classified under CWE-476 as a NULL Pointer Dereference, which represents a fundamental programming error where code assumes a pointer will not be null without proper validation. This type of error directly enables denial of service conditions and potentially provides a pathway for more sophisticated exploitation techniques.
The operational impact of CVE-2017-9083 extends beyond simple application crashes, as it can be exploited to disrupt document processing workflows and potentially serve as a vector for more complex attacks. When exploited through crafted PDF files, the vulnerability can cause applications using the vulnerable poppler library to terminate unexpectedly, leading to service disruption for end users and administrators. The segmentation fault behavior makes this vulnerability particularly concerning in automated document processing environments where continuous operation is expected. From an attacker perspective, this flaw aligns with ATT&CK technique T1203 (Exploitation for Client Execution) as it can be leveraged to cause application instability and potentially serve as a stepping stone for more advanced exploitation. The vulnerability is particularly dangerous in environments where users frequently open untrusted PDF files, as simply viewing a malicious document could trigger the crash condition.
Mitigation strategies for CVE-2017-9083 primarily focus on updating to patched versions of the poppler library, with version 0.56.0 and later containing the necessary fixes for this NULL pointer dereference issue. System administrators should prioritize patching affected applications that utilize the vulnerable library, including Evince, Okular, and any other software products that depend on poppler for PDF processing capabilities. Additionally, implementing proper input validation and sandboxing mechanisms can help reduce the impact of such vulnerabilities in environments where patching may be delayed. Organizations should also consider deploying network-based intrusion detection systems that can identify and block malformed PDF files that may exploit this vulnerability. The fix implemented in the patched versions typically involves adding proper null pointer checks before dereferencing pointers within the JPXStream::readUByte function, ensuring that the application gracefully handles malformed input rather than crashing. Regular security assessments and vulnerability scanning should be conducted to identify any remaining instances of the vulnerable library version within the organization's software ecosystem.