CVE-2020-27372 in Basic V
Summary
by MITRE • 10/11/2021
A buffer overflow vulnerability exists in Brandy Basic V Interpreter 1.21 in the run_interpreter function.
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Analysis
by VulDB Data Team • 10/14/2021
The buffer overflow vulnerability identified in Brandy Basic V Interpreter 1.21 represents a critical security flaw that could enable arbitrary code execution through improper memory handling within the run_interpreter function. This interpreter, designed for executing basic programming language scripts, fails to validate input lengths before processing them, creating an exploitable condition where maliciously crafted input can overwrite adjacent memory locations. The vulnerability stems from insufficient bounds checking mechanisms that allow data to be written beyond the allocated buffer boundaries, potentially corrupting program execution flow and enabling attackers to inject and execute malicious code. Such flaws are particularly dangerous in interpreted environments where user input is directly processed without adequate sanitization measures.
The technical implementation of this buffer overflow occurs within the run_interpreter function where the interpreter processes input commands and variables without proper validation of string lengths or buffer boundaries. When the interpreter encounters input data exceeding predetermined buffer limits, it continues writing data beyond allocated memory regions, causing stack corruption and potentially allowing attackers to overwrite return addresses, function pointers, or other critical program variables. This type of vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions, and represents a classic example of improper input validation that violates fundamental security principles. The attack surface is particularly concerning as it affects the core execution engine of the interpreter, making it a prime target for exploitation.
Operationally, this vulnerability presents significant risks to systems running Brandy Basic V Interpreter 1.21, as it could allow remote attackers to execute arbitrary code with the privileges of the interpreter process. The impact extends beyond simple denial of service, potentially enabling full system compromise through privilege escalation techniques or lateral movement within networked environments. Attackers could exploit this vulnerability by crafting specially formatted basic scripts or command inputs that trigger the buffer overflow condition, leading to unauthorized access, data exfiltration, or system takeover. The vulnerability affects both local and remote execution scenarios, making it particularly dangerous in environments where the interpreter processes untrusted user input. This weakness could be leveraged in combination with other techniques to establish persistent access or escalate privileges within compromised systems.
Mitigation strategies for this vulnerability should prioritize immediate patching of the interpreter software to address the buffer overflow condition in the run_interpreter function. Organizations should implement input validation mechanisms that enforce strict bounds checking on all user-supplied data before processing, ensuring that no data exceeds predetermined buffer limits. Additionally, memory protection mechanisms such as stack canaries, address space layout randomization, and data execution prevention should be enabled to reduce exploitability. System administrators should consider implementing network segmentation and access controls to limit exposure of vulnerable systems, while also monitoring for suspicious activity related to interpreter execution. The remediation efforts should align with industry best practices for buffer overflow prevention and follow the principle of least privilege to minimize potential impact from successful exploitation attempts. Regular security assessments and code reviews should be conducted to identify similar vulnerabilities in other software components, ensuring comprehensive protection against similar threats.