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The U.S. Cybersecurity and Infrastructure Security Agency (CISA) has added a serious vulnerability affecting SonicWall Secure Mobile Access (SMA) 100 Series appliances to its Known Exploited Vulnerabilities (KEV) catalog. This move comes after confirmed evidence of active exploitation in the wild.
The flaw, officially cataloged as CVE-2021-20035, carries a CVSS severity rating of 7.2 and involves an operating system command injection bug in the management interface of affected SonicWall devices. If successfully exploited, attackers with valid credentials can execute arbitrary commands under the low-privileged “nobody” user — a dangerous vector that can lead to full system compromise.
SonicWall first disclosed the vulnerability in September 2021, offering patches across affected SMA devices, including SMA 200, 210, 400, 410, and virtual instances like SMA 500v deployed on ESX, KVM, AWS, and Azure. Although the exploit details remain closely guarded, its presence in the KEV list underscores its potential for widespread damage.
the Exploited Vulnerability
– Vulnerability ID: CVE-2021-20035
– Severity Score (CVSS): 7.2
– Type: OS Command Injection
- Impact: Remote Code Execution via “nobody” user privileges
– Affected Products:
– SMA 200, 210, 400, 410
– SMA 500v (ESX, KVM, AWS, Azure)
– Affected Versions:
- 10.2.1.0-17sv and earlier → Patch: 10.2.1.1-19sv or later
- 10.2.0.7-34sv and earlier → Patch: 10.2.0.8-37sv or later
- 9.0.0.10-28sv and earlier → Patch: 9.0.0.11-31sv or later
– Attack Requirements: Remote authenticated access
– Confirmed Exploitation: Yes
– CISA Action: Added to KEV catalog
- Mitigation Deadline for FCEB Agencies: May 7, 2025
This addition means all federal agencies under the Federal Civilian Executive Branch (FCEB) must urgently patch or mitigate against this vulnerability to prevent further exposure. CISA’s warning is often a bellwether for wider industry concern, suggesting the private sector should also evaluate and update their SMA deployments.
What Undercode Say:
The inclusion of CVE-2021-20035 in CISA’s KEV catalog is no mere formality — it is a signal flare for defenders across both public and private sectors. What stands out here isn’t just the vulnerability itself, but the environment in which it’s being exploited: secure access gateways, which often serve as the front door to sensitive internal systems.
Let’s break down why this is a high-priority issue:
– Remote Authentication = Realistic Exploit Scenarios
The flaw requires authenticated access, which narrows the attack vector — but not by much. Credential phishing, session hijacking, or insider threats can all serve as entry points. For systems exposed to the internet, this becomes a far more dangerous scenario.
– Privilege Level Isn’t Always the Limiting Factor
Though the commands execute under the “nobody” user, history shows that even low-privileged execution can be chained with local privilege escalation (LPE) bugs or misconfigurations to reach full root access.
– Government-Backed Interest and Real-World Use
When CISA speaks, the cybersecurity world listens. Their declaration that this flaw is being exploited “in the wild” typically indicates a strong signal from threat intelligence feeds, often tied to state-sponsored or financially motivated APT groups.
– Patch Management Lag Still a Threat Vector
Despite the vulnerability’s disclosure dating back to 2021, many organizations may have yet to apply the fixes — especially in virtualized environments like AWS and Azure where snapshot-based deployments can lag behind current patch levels.
- SonicWall’s Popularity Makes This Scalable
SMA appliances are widely deployed in healthcare, finance, education, and government networks. An exploit that targets these systems can be scripted, scaled, and sold — making it a favorite among ransomware gangs and cybercriminal marketplaces.
– Why KEV Matters
The Known Exploited Vulnerabilities list is not speculative. It’s a blacklist of actively attacked flaws. When CISA updates it, it often reflects post-mortem analysis from real-world incidents or strong signals from honeypots and threat feeds.
From a blue team perspective, organizations running affected SMA versions should prioritize:
– Reviewing system logs for suspicious “nobody” user activity
– Deploying available patches ASAP
– Enhancing monitoring around management interfaces
– Segmenting network access to isolate exposed appliances
– Disabling remote access features if not essential
From an offensive security mindset, this vulnerability represents a significant entry point — especially in cases where credential reuse or weak password policies are in place. Penetration testers and red teams should consider including it in their playbooks when assessing perimeter defenses.
Fact Checker Results
- ✅ CISA officially listed CVE-2021-20035 in its KEV catalog as of April 2025.
- ✅ SonicWall has acknowledged the vulnerability and issued patches.
- ✅ Exploitation in the wild has been confirmed by trusted sources, including U.S. federal security entities.
References:
Reported By: thehackernews.com
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