CVE-2018-21009 in Poppler
Summary
by MITRE
Poppler before 0.76.0 has an integer overflow in Parser::makeStream in Parser.cc.
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Analysis
by VulDB Data Team • 12/13/2023
The vulnerability identified as CVE-2018-21009 represents a critical integer overflow flaw within the Poppler PDF rendering library version 0.76.0 and earlier. This issue resides in the Parser::makeStream function located in the Parser.cc source file, making it a core component of the PDF parsing infrastructure that handles stream data processing. The vulnerability stems from insufficient input validation and arithmetic overflow handling when processing PDF stream objects, which can lead to unpredictable behavior and potential exploitation by malicious actors. Poppler is widely used across various operating systems and applications for PDF document rendering, making this vulnerability particularly concerning for system security.
The technical flaw manifests when the Parser::makeStream function processes stream data without proper bounds checking on integer values that determine buffer allocation sizes. An attacker can craft a malicious PDF file containing specially formatted stream data that triggers an integer overflow during the calculation of memory allocation requirements. This overflow results in a situation where the calculated buffer size becomes significantly smaller than intended, leading to insufficient memory allocation for the actual data being processed. The vulnerability falls under the CWE-190 category of Integer Overflow or Wraparound, specifically representing an unchecked integer arithmetic condition that can cause memory corruption. When the system attempts to write data beyond the allocated buffer boundaries, it can overwrite adjacent memory locations, potentially leading to arbitrary code execution or denial of service conditions.
The operational impact of this vulnerability extends across multiple platforms and applications that rely on Poppler for PDF processing, including web browsers, document viewers, and server-side PDF handling systems. Attackers can exploit this weakness by delivering malicious PDF files that trigger the overflow condition during normal PDF parsing operations, potentially allowing them to execute arbitrary code with the privileges of the affected application. The vulnerability is particularly dangerous in server environments where PDF processing occurs without user interaction, as it can be exploited through automated means. Systems using older versions of Poppler, such as those found in various Linux distributions, mobile operating systems, and enterprise applications, are at risk of being compromised. The exploitation can result in complete system compromise, data exfiltration, or service disruption, depending on the execution environment and privilege levels of the affected processes. This vulnerability directly relates to ATT&CK technique T1203 by enabling initial access through malicious document delivery and can be leveraged for privilege escalation or lateral movement within compromised networks.
Mitigation strategies for CVE-2018-21009 primarily involve upgrading to Poppler version 0.76.0 or later, where the integer overflow has been properly addressed through enhanced input validation and arithmetic overflow protection mechanisms. System administrators should prioritize patching affected systems and applications that utilize Poppler, particularly those handling untrusted PDF content. Additional protective measures include implementing PDF content filtering and sandboxing mechanisms, restricting PDF processing to trusted sources only, and monitoring for suspicious PDF file characteristics that might indicate exploitation attempts. Organizations should also consider deploying intrusion detection systems capable of identifying malicious PDF file patterns and implementing network segmentation to limit the potential impact of successful exploitation. The fix typically involves adding proper integer overflow checks before memory allocation calculations and implementing robust bounds checking for all stream data processing operations to prevent the arithmetic overflow condition from occurring in the first place.