MAWK Stack Buffer Overflow (CVE-2017-20229) - Update Now

Patch now - CVE-2017-20229 is a critical stack-based buffer overflow in MAWK versions 1.3.3-17 and earlier that grants an attacker unauthenticated remote code execution by processing crafted input, hijacking program flow via ROP to spawn a command shell. Immediate upgrade to version 1.3.4-18 is required.

Overview

A critical stack-based buffer overflow vulnerability has been identified in MAWK, a lightweight implementation of the AWK programming language. Tracked as CVE-2017-20229, this flaw exists due to insufficient boundary checks when processing user-supplied input. Successful exploitation could allow an attacker to execute arbitrary code on the affected system.

Vulnerability Details

MAWK versions 1.3.3-17 and earlier fail to properly validate the length of input before copying it into a fixed-size stack buffer. By crafting specific malicious input, an attacker can overflow this buffer. This overflow corrupts adjacent memory and can be leveraged to hijack the program’s execution flow. Attackers typically use a technique called Return-Oriented Programming (ROP) to chain together snippets of existing code, ultimately allowing them to spawn a command shell with the same privileges as the MAWK application.

Impact Assessment

This vulnerability is rated CRITICAL with a CVSS score of 9.8. The primary risk is remote code execution. If MAWK is used to process untrusted data-a common scenario in scripting and text processing-an attacker could gain a foothold on the system. The impact severity depends on the privileges of the user running MAWK; if run by a privileged account or a system service, it could lead to a full system compromise. For context on how such vulnerabilities lead to incidents, you can review historical breach reports.

Remediation and Mitigation

The most effective action is immediate patching.

1. Update MAWK: Upgrade to MAWK version 1.3.4-18 or later from your official operating system vendor repositories. Use your system’s package manager (e.g., apt, yum, dnf).
2. Verify Version: After updating, confirm the installed version with the command mawk -W version.
3. Temporary Mitigation: If immediate patching is impossible, restrict the use of MAWK to process only trusted data sources. This is a high-risk workaround and not a substitute for patching.
4. General Security Hygiene: Adhere to the principle of least privilege by ensuring applications and scripts do not run with unnecessary elevated permissions.

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