External risk intelligence

Arm Whois Stack Buffer Overflow Allows Code Execution

CVE advisorySeverity: CRITICAL (CVSS 9.3)

CVE-2018-25427

The vulnerability affects a WHOIS client. While typically a local user tool, it initiates network requests to public servers. Public exposure is possible if integrated into automated services processing untrusted input, though it is rarely deployed as a public-facing edge service.

Buffer Overflow

Halo Surface Signal: 3 out of 5 — possibly public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

This vulnerability involves a buffer overflow in a network utility that could allow remote code execution if a user processes specially crafted input. The main concern is confirming its relevance and exposure within our environment.

Flaw allows code execution via oversized input.
Understand potential remote code execution risks.
Confirm relevance and exposure in our environment.

Attack Path

How an attacker could exploit the issue

An attacker could exploit this vulnerability by sending specially crafted, oversized input to the IP address or domain field of the Arm Whois client. This input, exceeding 658 bytes and containing shellcode, could overwrite critical program structures, leading to arbitrary code execution when the application processes the input.

No special access required.
Oversized input to IP or domain field.
Arbitrary code execution risk.

Live Threat

Current exploitation, exposure, and threat context

This vulnerability could allow an attacker to execute arbitrary code on a system running Arm Whois by sending specially crafted, oversized input to the IP address or domain field. This could happen when the application processes malicious input, potentially leading to command execution on the affected system.

System code execution.
Malicious input processed by the application.
Compromised application service behavior.

Operational Fix

Recommended remediation, mitigation, and detection steps

The Arm Whois client, if deployed in automated systems processing untrusted input, could be the responsibility of application owners or platform teams. The immediate first step is to confirm the presence and reachability of this technology, identify the accountable owner, and then prioritize remediation efforts based on identified risk.

Confirm deployment and reachability.
Identify accountable owner and scope.
Plan remediation based on risk.

Supplementary metadata

CVSS vector

Validate whether this threat affects your internet-facing exposure.

Halo Threat Intelligence helps prioritize remediation with Halo Surface Signal and H/A/L/O context. Start exposure validation with a free external attack surface trial.

Free EASM Trial See How Signal Works

Frequently asked questions

What is Arm Whois?

Arm Whois is a network utility designed to query WHOIS databases, which store information about domain name ownership and IP address registration. Users typically run this software to look up technical details about internet resources. While often used as a standalone desktop tool, it can also be embedded into scripts or automated services that need to programmatically fetch registration data from external sources.

What does stack-based buffer overflow mean for CVE-2018-25427?

This vulnerability, classified as CWE-121, occurs when the software lacks proper checks on the amount of data it accepts. In this case, the application allocates a fixed amount of memory on the stack for input. By sending more than 658 bytes of data, an attacker can overflow this space, overwrite important internal program control structures—specifically the structured exception handler—and force the application to run attacker-provided code instead of its intended function.

How can an attacker trigger this vulnerability?

An attacker triggers this flaw by supplying a malicious, oversized string into the IP address or domain query field that the application processes. It is important to note that the vulnerability does not trigger during normal, compliant usage of the software with valid domain names or IP addresses. The exploit requires the specific intent of providing a malformed input exceeding the defined buffer size to manipulate the application's execution flow.

Is my system at risk if I run Arm Whois?

Risk depends on your specific deployment, as Halo Surface Signal notes that this is typically a local user tool. While it is not usually a public-facing edge service, you should be concerned if your instance is integrated into automated systems that process untrusted, externally sourced data. If the application is only used manually by a local user, the likelihood of a successful remote attack is lower, though the underlying code remains vulnerable.

What should I do if I have Arm Whois in my environment?

Your first step is to perform an inventory to confirm where Arm Whois is installed and how it is used. Determine if any instances are reachable from the network or used by automated services to handle external input. Once you have identified these systems and assigned an accountable owner, you can evaluate the risk to your infrastructure and coordinate remediation efforts to address the potential for arbitrary code execution.

References

Written by Nicholas Merritt

Nicholas Merritt is VP of Security Solutions at Halo Security. With more than 25 years across application security, vulnerability prioritization, and offensive security, he helps teams translate threat data into practical exposure validation and remediation focus. He authors Halo Threat Intelligence CVE advisories using Halo Surface Signal and H/A/L/O context to prioritize internet-facing risk.