CVE-2016-2790 in Firefox
Summary
by MITRE
The graphite2::TtfUtil::GetTableInfo function in Graphite 2 before 1.3.6, as used in Mozilla Firefox before 45.0 and Firefox ESR 38.x before 38.7, does not initialize memory for an unspecified data structure, which allows remote attackers to cause a denial of service or possibly have unknown other impact via a crafted Graphite smart font.
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Analysis
by VulDB Data Team • 07/09/2022
The vulnerability identified as CVE-2016-2790 represents a critical memory initialization flaw within the Graphite 2 smart font handling component that was extensively used in Mozilla Firefox and its Extended Support Release versions. This issue affects Graphite 2 versions prior to 1.3.6 and specifically impacts Firefox versions before 45.0 and Firefox ESR 38.x before 38.7. The flaw resides in the graphite2::TtfUtil::GetTableInfo function which fails to properly initialize memory for an unspecified data structure during the processing of Graphite smart fonts. This memory initialization failure creates a potential security vector that could be exploited by remote attackers through carefully crafted malicious smart font files.
The technical nature of this vulnerability stems from improper memory management practices within the Graphite font rendering system. When Firefox processes Graphite smart fonts, the GetTableInfo function attempts to parse and extract table information from font files without adequately initializing all memory regions that will be used for data storage. This incomplete initialization creates a condition where uninitialized memory contents may be accessed or interpreted by the application, potentially leading to unpredictable behavior. The vulnerability manifests when the application encounters specially crafted Graphite smart font files that trigger the problematic code path, causing the memory handling routine to behave in unexpected ways.
From an operational perspective, this vulnerability presents significant risks to affected systems as it can be exploited to cause denial of service conditions by forcing applications to crash or become unresponsive. The remote exploitation capability means that attackers can potentially compromise system availability without requiring local access or user interaction beyond visiting a malicious website or opening a malicious document. The potential for additional unknown impacts exists because uninitialized memory may contain sensitive data or patterns that could be leveraged for more sophisticated attacks, though the specific nature of these potential additional impacts remains unclear without further analysis of the uninitialized memory contents and their subsequent usage.
The vulnerability aligns with CWE-457 which addresses the use of uninitialized variables and memory management issues in software development. This flaw demonstrates the importance of proper memory initialization practices and follows patterns commonly seen in buffer overflows and memory corruption vulnerabilities that have historically led to severe security consequences. Organizations should consider implementing mitigations based on the ATT&CK framework's defensive strategies for memory corruption vulnerabilities, including application sandboxing, input validation, and regular software updates to address known vulnerabilities.
Mitigation strategies for this vulnerability primarily focus on immediate software updates to versions that contain the necessary patches and fixes. System administrators should prioritize updating Firefox installations to versions 45.0 or later for regular releases and 38.7 or later for ESR releases to eliminate exposure to this vulnerability. Additionally, implementing network-level controls such as content filtering and web application firewalls can provide additional protection layers while ensuring proper patch management. Organizations should also consider implementing monitoring for suspicious font file handling activities and establishing incident response procedures to address potential exploitation attempts. The vulnerability serves as a reminder of the importance of thorough memory management practices and proper initialization routines in security-critical applications, particularly those handling untrusted input data such as font files from external sources.