CVE-2015-2991 in NScripter
Summary
by MITRE
Buffer overflow in NScripter before 3.00 allows remote attackers to execute arbitrary code via crafted save data.
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Analysis
by VulDB Data Team • 11/27/2017
The vulnerability identified as CVE-2015-2991 represents a critical buffer overflow flaw within NScripter versions prior to 3.00, a scripting engine commonly used in visual novel and game development environments. This vulnerability specifically targets the handling of save data files, which are typically used to store game progress and player state information. The flaw arises from inadequate input validation and memory management when processing external save data, creating an exploitable condition that can be triggered by maliciously crafted data structures.
The technical implementation of this buffer overflow occurs during the parsing of save files, where the application fails to properly validate the size or structure of incoming data before copying it into fixed-size memory buffers. When an attacker crafts save data that exceeds the allocated buffer boundaries, the excess data overflows into adjacent memory regions, potentially overwriting critical program variables, return addresses, or other executable code. This memory corruption can be leveraged to redirect program execution flow and ultimately execute arbitrary code with the privileges of the affected application.
From an operational perspective, this vulnerability poses significant risks to both end users and developers who utilize NScripter for creating interactive multimedia applications. Attackers can exploit this flaw remotely by distributing malicious save files through various channels including game distribution platforms, social media, or compromised websites. The impact extends beyond simple code execution to potentially allow full system compromise, especially when the vulnerable application runs with elevated privileges or has access to sensitive system resources. The vulnerability's remote exploitability makes it particularly dangerous as it requires no local access to the target system.
The vulnerability aligns with CWE-121, which describes heap-based buffer overflow conditions, and represents a classic example of improper input validation in memory management operations. From an attack framework perspective, this vulnerability maps to multiple ATT&CK techniques including TA0002 Execution through the use of code injection methods, and potentially TA0004 Privilege Escalation if the application has elevated permissions. The exploitation chain typically involves crafting a malicious save file with carefully constructed data that triggers the buffer overflow, followed by payload delivery that leverages the overwritten memory to achieve remote code execution.
Mitigation strategies for CVE-2015-2991 primarily focus on immediate remediation through software updates to NScripter version 3.00 or later, which contain proper input validation and memory management fixes. Organizations should implement strict file validation policies for save data handling, particularly when processing user-generated content or third-party files. Additional protective measures include restricting write permissions for save data directories, implementing application sandboxing, and deploying network-based intrusion detection systems that can identify and block suspicious save file patterns. Regular security assessments of applications using NScripter should include vulnerability scanning for similar buffer overflow conditions, and developers should adopt secure coding practices such as bounds checking, use of safe string handling functions, and memory protection mechanisms to prevent similar vulnerabilities from emerging in future implementations.