CVE-2018-12115 in Node.js
Summary
by MITRE
In all versions of Node.js prior to 6.14.4, 8.11.4 and 10.9.0 when used with UCS-2 encoding (recognized by Node.js under the names `'ucs2'`, `'ucs-2'`, `'utf16le'` and `'utf-16le'`), `Buffer#write()` can be abused to write outside of the bounds of a single `Buffer`. Writes that start from the second-to-last position of a buffer cause a miscalculation of the maximum length of the input bytes to be written.
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Analysis
by VulDB Data Team • 05/04/2023
This vulnerability affects Node.js versions before 6.14.4, 8.11.4, and 10.9.0 when utilizing UCS-2 encoding methods including 'ucs2', 'ucs-2', 'utf16le', and 'utf-16le'. The flaw resides in the Buffer#write() method implementation where specific boundary conditions trigger incorrect length calculations during string encoding operations. When write operations begin from the second-to-last position of a buffer, the internal logic fails to properly account for the maximum length of input bytes that can be safely written, creating a potential buffer overflow condition.
The technical exploitation occurs through improper bounds checking during UCS-2 string encoding processes. Node.js internally handles UCS-2 encoded strings by converting them to UTF-16 format, but the miscalculation in length determination causes the write operation to extend beyond the intended buffer boundaries. This behavior stems from how the method calculates the maximum number of bytes that can be written based on the starting position and available buffer space, leading to memory corruption when the write operation extends into adjacent memory regions.
Operational impact of this vulnerability extends across numerous Node.js applications that utilize UCS-2 encoding for string processing, data serialization, or network communication protocols. Attackers can leverage this flaw to perform out-of-bounds memory writes, potentially leading to arbitrary code execution, denial of service conditions, or information disclosure. The vulnerability is particularly concerning in server-side applications where user input is processed through Buffer operations, as it could enable remote code execution if the application handles untrusted data through UCS-2 encoded buffer operations.
The vulnerability maps to CWE-121 Stack-based Buffer Overflow and CWE-787 Out-of-bounds Write within the Common Weakness Enumeration framework, representing a classic buffer management flaw in string handling operations. From an adversarial perspective, this vulnerability aligns with ATT&CK technique T1059.007 Command and Scripting Interpreter: PowerShell and T1059.006 Command and Scripting Interpreter: Python, as attackers could potentially exploit it through malicious input processing in Node.js environments. Mitigation strategies include upgrading to patched Node.js versions, implementing input validation for buffer operations, and avoiding UCS-2 encoding when possible. Organizations should also consider runtime protections and memory corruption detection mechanisms to reduce the attack surface and prevent exploitation of similar buffer-related vulnerabilities.