CVE-2018-15503 in Swoole
Summary
by MITRE
The unpack implementation in Swoole version 4.0.4 lacks correct size checks in the deserialization process. An attacker can craft a serialized object to exploit this vulnerability and cause a SEGV.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 05/02/2023
The vulnerability identified as CVE-2018-15503 resides within the Swoole PHP extension version 4.0.4, specifically within its unpack implementation during the deserialization process. This flaw represents a critical security weakness that can be exploited through crafted serialized data to trigger a segmentation fault, effectively causing a denial of service condition. The vulnerability stems from insufficient validation of data sizes during the unpacking operation, which allows attackers to manipulate the deserialization flow through carefully constructed malicious payloads. Such an issue falls under the category of improper input validation and memory handling, creating a pathway for attackers to disrupt normal application operations.
The technical exploitation of this vulnerability occurs when Swoole processes serialized data that contains malformed size indicators or unexpected data lengths within the unpack function. During deserialization, the system attempts to allocate memory or process data based on the size parameters specified in the serialized object without adequate verification of these values. This lack of size validation creates an opportunity for attackers to craft payloads that cause the application to read or write beyond allocated memory boundaries, resulting in a segmentation fault that terminates the process. The flaw demonstrates characteristics consistent with buffer over-read conditions and improper memory management as defined by CWE-129 and CWE-787, where insufficient bounds checking leads to memory corruption.
The operational impact of this vulnerability extends beyond simple denial of service, as it can potentially be leveraged to execute arbitrary code or escalate privileges within the application environment. When exploited successfully, the segmentation fault can provide attackers with opportunities to manipulate the application's execution flow, potentially leading to remote code execution depending on the system configuration and available attack surface. Applications using Swoole version 4.0.4 that process untrusted serialized data are particularly at risk, as the vulnerability can be triggered through various input vectors including network requests, file uploads, or any mechanism that involves deserialization of external data. This weakness aligns with ATT&CK technique T1203, which involves the exploitation of software vulnerabilities to gain unauthorized access or execute malicious code.
Mitigation strategies for CVE-2018-15503 should prioritize immediate patching of the Swoole extension to version 4.0.5 or later, which includes proper size validation in the unpack implementation. Organizations should also implement strict input validation for all serialized data, particularly when processing external inputs, and consider employing sandboxing techniques to limit the potential impact of any successful exploitation attempts. Additional defensive measures include monitoring for unusual segmentation fault patterns in application logs and implementing network segmentation to limit the attack surface. The vulnerability highlights the importance of proper memory management and input validation in high-performance PHP extensions, as outlined in industry best practices for secure coding and application security. Regular security assessments and dependency updates should be maintained to prevent similar issues from arising in other components of the software stack.