External risk intelligence

Accellion FTA Command Execution Vulnerability.

CVE advisoryKnown Exploit

CVE-2021-27104

Affected Accellion FTA systems are vulnerable to OS command execution via crafted requests, posing a business risk of unauthorized system control and data compromise.

5Halo Surface Signal

OS Command Injection

Accellion Fta

9_12_370 and earlier

External exposure likelihood

Halo Surface Signal score for CVE-2021-27104

Accellion FTA is a managed file transfer appliance designed specifically to be internet-facing to facilitate the transfer of files between external parties and internal users. As an edge appliance typically placed in the DMZ to handle external connections, its administrative and service endpoints are frequently exposed to the public internet by design.

Horizon Alert

Summary of the vulnerability and why it matters

Accellion FTA, a file transfer solution, is susceptible to a vulnerability that allows for the execution of operating system commands. This flaw can be triggered through a specifically crafted POST request directed at certain administrative endpoints within the application. The successful exploitation of this weakness could lead to significant business risk for organizations utilizing the affected software.

Vulnerable component: Accellion FTA application
Core weakness: OS command execution via crafted request
Main business impact: Unauthorized system control

Attack Path

How an attacker could exploit the issue

This vulnerability allows an attacker to execute commands on the affected system. This could lead to unauthorized access and control over the system, potentially impacting data confidentiality, integrity, and availability. The attack leverages a specific vulnerability in how the system handles certain requests, enabling an attacker to inject and run malicious commands. Such an event poses a significant risk to the affected organization.

Exposed to the internet.
Attacker sends a crafted POST request.
Attacker gains system control.

Live Threat

Current exploitation, exposure, and threat context

This vulnerability could allow attackers to execute commands on affected systems. This could lead to unauthorized access, data theft, or disruption of services. The ease of exploitation and potential for widespread damage suggest a significant risk to organizations using the affected product.

Likely attacker skill level: Low
Required access or conditions: Publicly accessible system
Business risk or urgency: High

Priority actions

Operational Fix

Recommended remediation, mitigation, and detection steps

An organization should take immediate action to address a critical vulnerability in Accellion FTA software. This vulnerability allows for OS command execution through a crafted POST request to administrative endpoints. The potential impact includes unauthorized access and modification of systems and data, posing a significant business risk.

Identify all Accellion FTA assets.
Restrict network access to these assets.
Apply vendor-provided updates and validate.
Monitor for related security events.

Frequently asked questions

What is the Accellion FTA vulnerability and what is its core weakness?

The Accellion FTA vulnerability, identified as CVE-2021-27104, involves OS command execution. The core weakness is an OS command injection flaw (CWE-78) where a crafted POST request to specific admin endpoints allows attackers to run commands on the affected system. This means unauthorized control over the system is possible.

How can the Accellion FTA OS command execution vulnerability be exploited?

The vulnerability is exploited by sending a crafted POST request to various administrative endpoints within the Accellion FTA application. An attacker can leverage this weakness to inject and execute malicious operating system commands on the targeted system. This process does not require any special privileges or conditions beyond a publicly accessible system.

What is the potential business impact of the Accellion FTA command execution vulnerability?

The exploitation of this vulnerability can lead to significant business risks, including unauthorized system control, data theft, and disruption of services. Attackers gaining system control could compromise data confidentiality, integrity, and availability. The critical severity (CVSS 9.8) and external exposure of Accellion FTA highlight the high urgency for remediation.

What is the relevance of the Accellion FTA vulnerability, and why is it considered very likely to be exploited?

Accellion FTA is a managed file transfer appliance designed to be internet-facing, making its administrative and service endpoints frequently exposed to the public internet. This external exposure, combined with the critical nature of the OS command execution vulnerability, makes it a prime target. The Halo Surface Signal indicates a 'Very likely' exploitation risk due to its design as an edge appliance handling external connections.

What are the practical steps to respond to the Accellion FTA command execution vulnerability?

Immediate action is required. Organizations should identify all Accellion FTA assets, restrict network access to them, and apply vendor-provided updates (FTA 9_12_380 and later). After updating, validate the fix and diligently monitor for any related security events. The goal is to prevent unauthorized access, modification of systems and data, and mitigate significant business risks.

References

Written by Nicholas Merritt

External-surface CVE analysis and Halo Surface Signal prioritization for Halo Threat Intelligence.