CVE-2018-5885 in Snapdragon Mobile
Summary
by MITRE
While loading dynamic fonts, a buffer overflow may occur if the number of segments in the font file is out of range in Snapdragon Mobile and Snapdragon Wear.
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Analysis
by VulDB Data Team • 05/03/2020
The vulnerability described in CVE-2018-5885 represents a critical buffer overflow condition that affects mobile device systems utilizing Snapdragon processors. This flaw manifests specifically during the dynamic font loading process when the system encounters font files containing an excessive number of segments that exceed predetermined boundaries. The vulnerability impacts both Snapdragon Mobile and Snapdragon Wear product lines, indicating a widespread exposure across mobile computing platforms that rely on Qualcomm's mobile processor architecture. The buffer overflow condition arises from insufficient input validation and boundary checking mechanisms within the font rendering subsystem, creating potential exploitation vectors for malicious actors seeking to compromise device integrity.
The technical implementation of this vulnerability stems from the font handling code's failure to properly validate the segment count parameter within font files before processing. When a font file contains more segments than the allocated buffer can accommodate, the system overflows into adjacent memory regions, potentially allowing attackers to overwrite critical data structures or execute arbitrary code. This issue falls under the CWE-121 buffer overflow category, specifically manifesting as a stack-based buffer overflow within the font processing pipeline. The vulnerability's exploitation requires the attacker to craft a malicious font file with an excessive number of segments that triggers the overflow condition during normal font loading operations.
Operational impact of CVE-2018-5885 extends beyond simple system instability to encompass potential full system compromise and data exposure. Mobile devices affected by this vulnerability could experience application crashes, system hangs, or more severe outcomes including unauthorized code execution that could lead to complete device takeover. The nature of font loading as a common system function means that exploitation could occur through various attack vectors including malicious email attachments, compromised websites, or infected application downloads. This vulnerability particularly affects mobile operating systems that dynamically load fonts for display purposes, creating a persistent threat surface that remains active during normal device operation. The exploitation of this flaw aligns with ATT&CK technique T1059.007 for command and scripting interpreter execution, potentially enabling attackers to establish persistent access through compromised font rendering processes.
Mitigation strategies for CVE-2018-5885 require immediate patch deployment from device manufacturers and system administrators, as Qualcomm released security updates addressing the buffer overflow condition in affected Snapdragon processor versions. Organizations should implement comprehensive font validation policies that include segment count verification and boundary checking before font loading operations. Network-based defenses should include content filtering mechanisms that scan font files for suspicious segment counts, while endpoint protection solutions should monitor for unusual font processing behavior. System administrators should also consider implementing runtime protections such as stack canaries and address space layout randomization to reduce exploit reliability. The vulnerability highlights the importance of proper input validation and memory management in mobile operating systems, emphasizing that font rendering components must be treated with the same security rigor as core system functions. Regular security assessments of font handling code should be conducted to identify similar buffer overflow conditions that could compromise mobile device security.