External risk intelligence

SonicWall SMA Command Injection Vulnerability

CVE advisoryKnown Exploit

CVE-2021-20035

The management interface of SonicWall SMA100 appliances has a vulnerability that allows an authenticated attacker to inject commands. This could lead to denial of service, impacting system availability and potentially disrupting business operations. The risk is considered medium, as it requires authenticated access but

4Halo Surface Signal

OS Command Injection

Sonicwall Sma 200 Firmware

before 9.0.0.11-31sv10.2.0.0 to before 10.2.0.8-37sv10.2.1.0 to before 10.2.1.1-19sv

External exposure likelihood

Halo Surface Signal score for CVE-2021-20035

The vulnerability exists in the management interface of SonicWall SMA100 appliances. These devices are commonly deployed as internet-facing edge gateways or remote access appliances. While the vulnerability requires authentication, the management interface for such edge appliances is frequently exposed to the public internet, making it a likely target for remote access.

Horizon Alert

Summary of the vulnerability and why it matters

The management interface of SonicWall SMA100 appliances contains a flaw related to how special elements are handled. This weakness allows an authenticated attacker with network access to inject commands. The potential impact of this vulnerability is a denial of service for the affected systems.

Vulnerable: SonicWall SMA100 management interface
Flaw: Improper handling of special elements
Impact: System denial of service

Attack Path

How an attacker could exploit the issue

An attacker can exploit a vulnerability in the SMA100 management interface by first gaining authenticated access. Once authenticated, the attacker can inject commands, leading to potential disruption of services. This attack path impacts system availability and could allow for further unauthorized actions.

Requires authenticated access.
Injects arbitrary commands.
Leads to potential denial of service.

Live Threat

Current exploitation, exposure, and threat context

This vulnerability poses a medium-level risk to organizations by allowing authenticated attackers to inject commands, potentially causing a denial of service. The attack can be performed remotely by an attacker with low-skill privileges, requiring only authenticated access to the management interface. The damage could disrupt critical business operations.

Likely attacker skill level: Low.
Required access or conditions: Authenticated access.
Business risk or urgency: Medium.

Priority actions

Operational Fix

Recommended remediation, mitigation, and detection steps

This vulnerability in SonicWall SMA100 management interfaces allows authenticated attackers to inject commands, potentially causing denial of service. Organizations should prioritize identifying any exposed SMA100 devices and implementing vendor-provided fixes. Continuous monitoring for related activities is essential.

Identify exposed management interfaces.
Reduce exposure or isolate affected systems.
Apply vendor fixes and validate.
Monitor for related activity.

Frequently asked questions

What are SonicWall SMA100 appliances and their purpose in network security?

SonicWall SMA100 (Secure Mobile Access) appliances serve as secure gateways, enabling authorized users to access an organization's internal network and applications remotely from outside the corporate environment.

How does CVE-2021-20035 enable command injection in SonicWall SMA100?

CVE-2021-20035 is a command injection vulnerability arising from the improper neutralization of special elements within the SMA100's management interface. This flaw permits an authenticated attacker to insert and execute arbitrary commands as a 'nobody' user, potentially leading to a denial of service.

What is the attack vector for CVE-2021-20035 on SonicWall SMA100 appliances?

An authenticated attacker can exploit this vulnerability by injecting commands through the management interface. The attack vector is network-based, and it requires only authenticated access, not user interaction or privileges beyond authentication.

What is the relevance of CVE-2021-20035 given its threat advisory and Halo Surface Signal?

The Halo Surface Signal indicates a 'Likely' exploitation risk because SonicWall SMA100 appliances are often internet-facing remote access gateways, making their management interfaces, even with authentication requirements, probable targets for remote attackers.

What practical steps should organizations take to respond to the SonicWall SMA100 vulnerability?

Organizations should identify any exposed SMA100 management interfaces, reduce their exposure or isolate affected systems, and promptly apply vendor-provided fixes. Continuous monitoring for related malicious activity is also crucial.

References

Written by Nicholas Merritt

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