Recent findings by cybersecurity experts have unveiled a significant vulnerability within the Amazon EC2 Simple Systems Manager (SSM) Agent, a flaw that has since been patched. Should it have been exploited by malicious actors, the vulnerability could have led to unauthorized privilege escalation and code execution on affected systems.
The flaw in question allowed an attacker to create directories in unintended areas on the filesystem, execute arbitrary scripts with root privileges, and potentially escalate privileges or engage in other harmful activities by manipulating sensitive system directories, according to a report from Cymulate shared with The Hacker News.
The Amazon SSM Agent is a critical tool within the Amazon Web Services (AWS) framework, enabling IT administrators to remotely manage and execute commands on EC2 instances and on-premises servers. This software operates by processing commands and tasks outlined in SSM Documents, which typically comprise various plugins designed to execute specific functions, including running shell scripts and automating deployment or configuration tasks.
An inherent risk within the system arises from the SSM Agent’s dynamic creation of directories based on plugin specifications. This process leverages plugin IDs as part of the directory structure. However, inadequate validation of these IDs can introduce significant security vulnerabilities. The flaw discovered by Cymulate is classified as a path traversal vulnerability due to failures in the validation procedures attached to the plugin IDs, allowing an attacker to manipulate the filesystem and execute arbitrary code with elevated privileges.
The research highlights a particular function, “ValidatePluginId,” within pluginutil.go, which inadequately sanitizes input provided by users. This oversight permits attackers to introduce malicious plugin IDs that contain path traversal sequences (for example, ../), effectively facilitating unauthorized access to critical files and directories.
Exploiting this vulnerability, an attacker could use specially crafted plugin IDs while creating SSM documents, potentially executing arbitrary commands or scripts on the affected system’s file system. Such actions would significantly heighten the risk of privilege escalation and further malicious activity following initial exploitation.
The vulnerability was responsibly disclosed on February 12, 2025, and an update addressing the issue was released on March 5, 2025, in version 3.3.1957.0 of the Amazon SSM Agent. The release notes indicated that a “BuildSafePath” method was added to mitigate path traversal risks within the orchestration directory.
In light of these events, Amazon issued a statement to clarify that although the vulnerability was serious, it did not constitute a privilege escalation in the traditional sense, as it did not confer new permissions to any existing users. Instead, the situation hinged on the existing privileges needed to run SSM documents within their respective accounts. For businesses currently using version 3.3.1802.0 or later, no action is required. However, those on earlier versions are advised to update accordingly to mitigate potential risks.
This incident underscores the importance of rigorous input validation in software systems, particularly those managing sensitive operational infrastructures. As businesses increasingly rely on cloud services, understanding and addressing such vulnerabilities becomes critical for maintaining robust cybersecurity defenses.
