CVE-2018-3899 in Home Camera 27US
Summary
by MITRE
An exploitable code execution vulnerability exists in the QR code scanning functionality of Yi Home Camera 27US 1.8.7.0D. A specially crafted QR Code can cause a buffer overflow, resulting in code execution. The trans_info call can overwrite a buffer of size 0x104, which is more than enough to overflow the return address from the password_dst field
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Analysis
by VulDB Data Team • 06/04/2023
The vulnerability identified as CVE-2018-3899 represents a critical code execution flaw within the Yi Home Camera 27US firmware version 1.8.7.0D, specifically affecting the QR code scanning functionality. This issue falls under the category of buffer overflow vulnerabilities and demonstrates a significant security weakness that could be exploited by remote attackers to gain unauthorized control over affected devices. The vulnerability stems from improper input validation within the camera's QR code processing mechanism, where the device fails to properly sanitize or limit the size of data received through QR code scanning operations.
The technical implementation of this vulnerability involves a specific buffer overflow condition occurring during the processing of QR code data. The affected system utilizes a buffer named trans_info with a fixed size of 0x104 bytes, which translates to 260 bytes in decimal notation. When a maliciously crafted QR code is scanned, the data payload exceeds this buffer boundary, causing a classic stack-based buffer overflow condition. The vulnerability specifically targets the password_dst field within the function call structure, where the overflow directly overwrites the return address stored on the stack. This overwrite allows an attacker to redirect program execution flow to arbitrary code locations, effectively enabling remote code execution capabilities.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it provides attackers with complete control over the affected camera devices. Once exploited, the vulnerability allows for arbitrary code execution, which can lead to persistent backdoor access, data exfiltration, or the deployment of additional malicious payloads. The attack vector is particularly concerning because it requires no physical access to the device, as attackers can simply present a specially crafted QR code to the camera's scanning functionality. This makes the vulnerability suitable for remote exploitation and significantly increases the attack surface for potential adversaries. The vulnerability also demonstrates poor input validation practices and inadequate memory management within the firmware implementation.
Mitigation strategies for this vulnerability should focus on both immediate firmware updates and architectural improvements to prevent similar issues in the future. Device manufacturers should implement proper input validation mechanisms to ensure that QR code data does not exceed predetermined buffer boundaries, while also applying stack canary protections and address space layout randomization where applicable. The vulnerability aligns with CWE-121 Stack-based Buffer Overflow, which is a well-documented weakness in software security that has been consistently identified in various embedded systems and IoT devices. From an ATT&CK framework perspective, this vulnerability maps to techniques involving code injection and privilege escalation, potentially enabling adversaries to establish persistent access through the compromised camera devices. Organizations should also consider network segmentation and monitoring for unusual QR code scanning activities to detect potential exploitation attempts, while implementing robust firmware update mechanisms to ensure timely remediation of such vulnerabilities across deployed device fleets.