CVE-2018-25427: Arm Whois 3.11 Stack-Based Buffer Overflow RCE

CVE-2018-25427: Stack-Based Buffer Overflow in Arm Whois 3.11

A critical stack-based buffer overflow vulnerability — assigned CVE-2018-25427 with a CVSS score of 9.8 (Critical) — has been formally catalogued in the NIST NVD database. The flaw resides in Arm Whois version 3.11, a lightweight Windows-based WHOIS lookup utility. Remote attackers can exploit the vulnerability by supplying an oversized input string to the IP address or domain lookup field, triggering a buffer overflow that overwrites the structured exception handler (SEH) and enables arbitrary code execution.

Vulnerability Overview

Technical Details

The vulnerability is a classic stack-based buffer overflow triggered when user-supplied input to the IP address or domain name field exceeds 658 bytes without adequate length validation. The application fails to perform bounds checking before copying input into a fixed-size stack buffer, resulting in a stack smash that overwrites the Structured Exception Handler (SEH) chain on Windows.

Attack Mechanics

An attacker crafts a malicious string longer than 658 bytes, embedding shellcode within the payload and overwriting the SEH record with a pointer into the attacker-controlled buffer. When the application encounters an exception (triggered by the overflow), the corrupted SEH record redirects execution to the shellcode.

Typical exploit structure:

[Padding: ~658 bytes] + [Next SEH overwrite: 4 bytes] + [SEH handler overwrite: 4 bytes] + [NOP sled + shellcode]

Exploitation impact:

• Remote code execution at the privilege level of the running process
• Full host compromise if the application runs with elevated privileges
• Arbitrary command execution on the affected Windows system

Affected Product

Arm Whois 3.11 is a legacy Windows application used for DNS and WHOIS lookups. It is a GUI-based utility that queries WHOIS servers to retrieve domain registration and IP address ownership information. The tool predates modern secure coding practices and was not developed with memory-safe patterns.

This vulnerability reflects a class of legacy Windows application flaws where developers relied on unbounded string operations (e.g., strcpy, gets) without input length validation — a pattern that was common in software developed in the late 1990s and early 2000s.

Context and Impact

The late NVD cataloguing of this 2018 flaw reflects the ongoing effort by NIST and the CVE program to formally assign identifiers and CVSS scores to older disclosed vulnerabilities. While Arm Whois 3.11 has a limited user base in 2026, the formal CVE assignment means:

• Vulnerability scanners that check against NVD will now flag running instances
• Security baseline tools will include it in compliance checks
• Security researchers can reference it in coordinated remediation efforts

Practical risk level:

• Limited — Arm Whois is a niche legacy utility with low adoption in enterprise environments
• Non-trivial in environments running legacy Windows workstations with old network utilities
• Any instance where the application runs with administrative privileges amplifies the risk

Remediation

1. Remove or replace Arm Whois 3.11 — use a modern WHOIS utility or web-based lookup service instead
2. Apply input validation — if maintaining a patched fork, replace unbounded string operations with safe alternatives (strncpy, strncat, bounds-checked variants)
3. Enable Windows exploit mitigations — Data Execution Prevention (DEP) and Address Space Layout Randomization (ASLR) can complicate exploitation on modern Windows versions
4. Restrict execution — apply Software Restriction Policies or AppLocker to prevent execution of unsanctioned legacy utilities on managed workstations

Safe string handling pattern (C):

// Vulnerable pattern
char buffer[658];
strcpy(buffer, user_input); // No bounds check
 
// Secure pattern
char buffer[658];
strncpy(buffer, user_input, sizeof(buffer) - 1);
buffer[sizeof(buffer) - 1] = '\0';

Key Takeaways

1. CVE-2018-25427 is a CVSS 9.8 Critical stack-based buffer overflow in Arm Whois 3.11, now formally catalogued in NVD
2. Attackers can achieve remote code execution by sending an input string exceeding 658 bytes, overwriting the SEH chain with shellcode
3. Authentication is not required — any user who can supply input to the application is a potential attack vector
4. Remediation: Remove or replace the legacy utility; no official patch is expected for this unmaintained software
5. Legacy application inventory reviews should flag Arm Whois 3.11 for immediate decommissioning

Sources

• CVE-2018-25427 — NIST NVD