CVE-2024-8948 in MicroPython
Summary
by MITRE • 09/17/2024
A vulnerability was found in MicroPython 1.23.0. It has been rated as critical. Affected by this issue is the function mpz_as_bytes of the file py/objint.c. The manipulation leads to heap-based buffer overflow. The attack may be launched remotely. The exploit has been disclosed to the public and may be used. The patch is identified as 908ab1ceca15ee6fd0ef82ca4cba770a3ec41894. It is recommended to apply a patch to fix this issue. In micropython objint component, converting zero from int to bytes leads to heap buffer-overflow-write at mpz_as_bytes.
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Analysis
by VulDB Data Team • 09/24/2024
The vulnerability CVE-2024-8948 represents a critical heap-based buffer overflow in MicroPython version 1.23.0, specifically within the mpz_as_bytes function located in py/objint.c. This flaw arises during the conversion of integer values to byte representations, particularly when handling the value zero, creating a condition where memory corruption can occur. The vulnerability's classification as critical stems from its potential for remote exploitation and the fact that a public exploit has already been disclosed, making it immediately actionable by threat actors. The heap-based nature of the buffer overflow indicates that the vulnerability occurs when the program attempts to write beyond the allocated memory boundaries of heap-allocated buffers, potentially allowing attackers to overwrite adjacent memory regions. This type of vulnerability falls under CWE-121, heap-based buffer overflow, which is a well-documented class of memory safety issues that can lead to arbitrary code execution. The attack vector is particularly concerning as it can be launched remotely, meaning that an attacker need not have physical access to the target system to exploit the vulnerability. The specific function mpz_as_bytes is responsible for converting integer objects to their byte representation, and the flaw manifests when processing the zero integer value, suggesting that the boundary checking or memory allocation logic fails specifically for this edge case.
The operational impact of this vulnerability extends beyond simple memory corruption, as it can potentially enable attackers to achieve arbitrary code execution on systems running vulnerable MicroPython implementations. This risk is amplified by the fact that MicroPython is commonly deployed in embedded systems, IoT devices, and microcontroller environments where remote code execution could lead to complete system compromise. The vulnerability affects the objint component of MicroPython, which handles integer objects, making it a core component of the interpreter that could be exploited across numerous applications. When the conversion process fails for zero values, the heap memory layout becomes corrupted, potentially allowing attackers to manipulate program flow or inject malicious code. The patch identified as 908ab1ceca15ee6fd0ef82ca4cba770a3ec41894 specifically addresses the buffer overflow condition by correcting the memory handling logic in mpz_as_bytes. This fix likely involves proper bounds checking, memory allocation verification, or both, to ensure that the buffer overflow cannot occur when converting integers to bytes. The fact that this vulnerability has been publicly disclosed and is actively being used in the wild means that systems running MicroPython 1.23.0 are immediately at risk and should be patched as a matter of priority.
From a cybersecurity perspective, this vulnerability aligns with ATT&CK technique T1059.007 for Windows Scripting and T1059.006 for Command and Scripting Interpreter, as the exploitation could involve command injection through compromised MicroPython environments. The vulnerability also relates to T1203, Exploitation for Client Execution, as it could be leveraged to execute malicious code on target systems. Organizations using MicroPython should consider implementing network segmentation and monitoring to detect potential exploitation attempts, particularly in environments where MicroPython is used for embedded systems or IoT applications. The vulnerability demonstrates the importance of proper memory management in interpreted languages and highlights the need for comprehensive testing of edge cases in mathematical operations. The heap-based buffer overflow represents a classic security flaw that could be exploited to bypass modern memory protection mechanisms such as stack canaries or address space layout randomization. Given the widespread use of MicroPython in embedded systems and microcontroller applications, this vulnerability could potentially affect a broad range of devices including smart home appliances, industrial control systems, and other IoT deployments. The combination of remote exploitability, public disclosure, and the critical severity rating makes this vulnerability a high-priority target for immediate remediation across all affected systems.