Most organizations spend a lot of time locking the front door of their cloud environments. Firewalls, access controls, and web application filters get the bulk of attention because that is where visible threats tend to show up.

But what leaves the network is just as important, and outbound traffic is often left wide open by default.

When a cloud workload is left without proper outbound controls, it can quietly become a channel for data theft.

Attackers who gain access to a compromised instance will almost always try to establish an outbound connection, whether to pull out sensitive files or set up a command-and-control link.

Those channels go undetected when no one is watching what exits the network. Security researchers at AWS identified this growing blind spot and published a detailed advisory on June 22, 2026, noting the risk applies to both traditional cloud workloads and the newer wave of AI-driven systems.

The AWS report shared with Cyber Security News (CSN) points to cases where unpatched vulnerabilities, such as CVE-2025-55182 (React2Shell), allowed attackers to gain code execution and immediately start exfiltrating data.

The report also highlights a newer risk tied to agentic AI systems. According to the OWASP Top 10 for Agentic Applications, threats like Agent Goal Hijack and Unexpected Code Execution mean AI agents can be manipulated into silently sending data outside the organization.

These agents often have access to tools, APIs, and code interpreters, making them high-value targets. Both scenarios share one common thread: unauthorized outbound traffic that goes unchecked.

AWS lays out a layered approach to closing this gap, addressing the problem at the network level, the DNS level, and the identity and access level at the same time.

The core issue is that most cloud environments treat outbound traffic as routine. Without centralized inspection, data can leave through open ports, encoded DNS queries, or HTTPS connections that hide the content inside.

Attackers are well aware of this and use these channels deliberately. DNS tunneling is one of the more subtle methods.

By encoding data inside DNS queries, attackers can bypass traditional firewall inspection entirely, since DNS traffic is essential for normal operations and often excluded from deep inspection rules.

AWS notes that Route 53 Resolver DNS Firewall must be deployed across VPCs to close this gap, as DNS queries handled by the VPC resolver do not pass through standard network inspection paths.

Architecture overview (Source - AWS) — Architecture overview (Source – AWS)

Another concern is what happens when stolen credentials are used to copy data to external storage.

Without endpoint-level policies restricting which storage buckets a workload can access, a compromised identity can move sensitive files to an attacker-controlled account in seconds. These actions can look completely normal without proper guardrails in place.

Layered Egress Controls and How to Apply Them

AWS outlines a phased strategy that organizations can follow to build their defenses without disrupting existing operations. The first step is enabling DNS Firewall across VPCs and activating threat detection to get immediate visibility into outbound traffic patterns.

From there, the focus shifts to foundational controls: deploying organization-wide policies that restrict what identities can access, setting up a centralized network firewall to inspect all internet-bound traffic, and applying endpoint policies that limit which external resources workloads can reach.

These controls work together to prevent both traditional workloads and AI agents from sending data where they should not.

The final phase involves automating the response. When a suspicious finding surfaces, automated workflows can update firewall block lists in real time, revoke credentials, and alert security teams before significant damage occurs.

AWS recommends centralizing all findings so teams can correlate signals across services and respond faster.

The same controls that protect a traditional cloud server also apply to AI agents. An agent running inside a cloud environment follows the same network paths as any other workload, facing the same domain filters, DNS rules, and data access restrictions when those controls are correctly in place.

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The post AWS Warns Outbound Traffic Blind Spots Can Enable Cloud Data Exfiltration appeared first on Cyber Security News.

Why Outbound Traffic Blind Spots Are Dangerous

Layered Egress Controls and How to Apply Them