City of Dallas Ransomware Incident Report

Elastio and AWS recently hosted a joint webinar, “Modern Ransomware Targets Recovery: Here’s What You Can Do to Stay Safe.” The session brought together experts to unpack how ransomware tactics are evolving and what organizations need to do differently to stay resilient. A clear theme emerged. Attackers are no longer focused on disruption alone. They are deliberately sabotaging recovery. Ransomware Has Shifted From Disruption to Recovery Sabotage Modern ransomware no longer relies on fast, obvious encryption of production systems. Instead, attackers often gain access months in advance. They quietly study the environment, including backup architectures, replication paths, and retention windows. Encryption happens slowly and deliberately, staying below detection thresholds while corrupted data propagates into snapshots, replicas, and backups. By the time the attack is triggered and ransom is demanded, recovery options are already compromised. This represents a fundamental shift in risk. Backups are no longer just a safety net. They are a primary target. Ransomware Risk Is Unquantifiable Without Proven Clean Recovery Points Ransomware risk becomes impossible to quantify when organizations cannot prove their recovery data is clean. Boards, regulators, and insurers are no longer reassured by the mere existence of backups. They want to know how quickly recovery can happen, which recovery point will be used, and how its integrity is verified. Most organizations cannot answer these questions with confidence because backup validation is not continuous. The consequences are real. Extended downtime, board-level exposure, insurance gaps, and growing regulatory pressure under frameworks such as DORA, NYDFS, and PRA. Without proven clean recovery points, ransomware becomes an unbounded business risk rather than a technical one. The Three Pillars of Ransomware Recovery Assurance The webinar emphasized that real ransomware resilience depends on three pillars working together. Immutability and isolation ensure backups are tamper-proof and stored separately, protected by independent encryption keys. AWS capabilities such as logically air-gapped vaults support this foundation.Availability focuses on whether recovery can happen fast enough to meet business expectations, particularly when identity systems are compromised. Clean-account restores and multi-party approval become critical.Integrity, the most overlooked pillar, ensures backups are continuously validated to detect encryption, corruption, malware, and fileless attacks, and to clearly identify the last known clean recovery point. If any pillar fails, recovery fails. For more information: Resilience by design: Building an effective ransomware recovery strategy | AWS Storage Blog Malware Scanning Is Not Ransomware Detection The speakers drew a clear distinction between traditional malware scanning and what is required to defend against modern ransomware. Signature-based tools look for known binaries, but today’s attacks often run in memory, use polymorphic techniques, and encrypt data without leaving a detectable payload. In these cases, the absence of malware does not mean the absence of damage. Effective ransomware defense requires detecting the impact on data itself, including encryption, corruption, and abnormal change patterns, not just the presence of malicious code. Validation Enables Faster, Safer Recovery Without Paying Ransom A real-world case study illustrated the value of recovery validation. Attackers encrypted data gradually over several days, allowing compromised data to flow into backups that appeared intact but were unsafe to restore. Through targeted threat hunting, Elastio identified a clean recovery point from roughly six days earlier, enabling the company to restore operations without paying the ransom. With downtime costs often reaching millions per day, even small reductions in recovery time have outsized financial impact. The takeaway was simple. Knowing where to recover from matters more than recovering quickly from the wrong place. Key Takeaways Ransomware now targets recovery, not just production.Attackers gain access early, encrypt data slowly, and ensure corruption spreads into replicas and backups before triggering an attack. By the time ransom is demanded, recovery paths are often already compromised.Backups alone are not proof of recoverability.Without continuous validation, organizations cannot confidently identify a clean recovery point, making ransomware risk impossible to quantify.True ransomware resilience depends on three pillars.Immutability and isolation protect backups from tampering, availability ensures recovery meets business expectations, and integrity validation confirms recovery data is usable. If integrity fails, recovery fails.Malware detection is not ransomware detection.Fileless and polymorphic attacks often evade signature-based tools. Detecting the impact on data, such as encryption and corruption, is critical.Provable recovery changes the economics of ransomware.Validated recovery points reduce downtime, avoid reinfection, and can eliminate the need to pay ransom, delivering measurable operational and financial impact. Additional Resources AWS ReInvent: How Motability Operations built a ransomware-ready backup strategy with AWS Backup & Elastio AWS re:Invent 2025 - Motability Operations' unified backup strategy: From fragmented to fortified

GuardDuty’s release of malware scanning on AWS Backup is an important enhancement to the AWS ecosystem, reflecting growing industry recognition that inspecting backup data has become a core pillar of cyber resilience. But real-world incidents show that ransomware often leaves no malware behind, making broader detection capabilities for encryption and zero-day attacks increasingly essential. Across industries, there are countless examples of enterprises with premium security stacks in place - EDR/XDR, antivirus scanners, IAM controls - still suffering extended downtime after an attack because teams couldn’t reliably identify an uncompromised recovery point when it mattered most. That’s because ransomware increasingly employs fileless techniques, polymorphic behavior, living-off-the-land tactics, and slow, stealthy encryption. These campaigns often reach backup andreplicated copies unnoticed, putting recovery at risk at the very moment organizations dependon it. As Gartner puts it: Modern ransomware tactics bypass traditional malware scanners, meaning backups may appear ‘clean’ during scans but prove unusable when restored. Equip your recovery environment with advanced capabilities that analyze backup data using content-level analytics and data integrity validation.”— Gartner, Enhance Ransomware Cyber Resilience With A Secure Recovery Environment, 2025 This is the visibility gap Elastio was designed to close. In this post, we walk through how Elastio’s data integrity validation works alongside AWS GuardDuty to support security and infrastructure teams through threat detection all the way to recovery confidence and why integrity validation has become essential in the age of identity-based and fileless attacks. What is AWS GuardDuty? AWS GuardDuty is a managed threat detection service that continuously monitors AWS environments for malicious or suspicious activity. It analyzes signals across AWS services, including CloudTrail, VPC Flow Logs, DNS logs, and malware protection scans, and produces structured security findings. GuardDuty integrates natively with Amazon EventBridge, which means every finding can be consumed programmatically and routed to downstream systems for automated response. For this integration, we focus on GuardDuty malware findings, including: Malicious file findings in S3Malware detections in EC2 environments These findings are high-confidence triggers that indicate potential compromise and warrant immediate validation of recovery data. Learn more about GuardDuty. Why a GuardDuty Finding Should Trigger Recovery Validation Malware detection is important, but it is no longer sufficient to validate data recoverability. Identity-based attacks dominate cloud breaches Today’s attackers increasingly rely on stolen credentials rather than exploits. With valid identities, they can: Use legitimate AWS APIsAccess data without dropping malwareBlend into normal operational behavior In these scenarios, there may be nothing malicious to scan, yet encryption or tampering can still occur. Fileless and polymorphic ransomware evade signatures Many ransomware families: Run entirely in memoryContinuously mutate their payloadsAvoid writing recognizable artifacts to disk Signature-based scanners may report “clean,” even as encryption spreads. Zero-day ransomware has no signatures By definition, zero-day ransomware cannot be detected by known signatures until after it has already caused damage - often widespread damage. The result is a dangerous failure mode: backups that scan clean but restore encrypted or corrupted data. Why Integrity Validation Changes the Outcome Elastio approaches ransomware from the impact side. Instead of asking only “is malware present?”, Elastio validates: Whether encryption has occurredWhat data was impactedWhen encryption startedWhich recovery points are still safe to restore The timeline above reflects a common real-world pattern: Initial access occurs quietlyEncryption begins days or weeks laterBackups continue, unknowingly capturing encrypted dataThe attack is only discovered at ransom time Without integrity validation, teams cannot know with confidence that their backups will work when they need them. This intelligence transforms a GuardDuty finding from an alert into an actionable recovery decision. Using GuardDuty as the Trigger for Recovery Validation Elastio’s new GuardDuty integration automatically initiates data integrity scans when GuardDuty detects suspicious or malicious activity. Instead of stopping at alerts, the integration immediately answers the implied next question: Did this incident affect our data, and can we recover safely? By validating backups and recovery assets in response to GuardDuty findings, Elastio reduces response time, limits attacker leverage, and enables faster, more confident recovery decisions. Architecture Overview At a high level: GuardDuty generates a malware findingThe finding is delivered to EventBridgeEventBridge routes the event into a trusted sender EventBusElastio’s receiver EventBus accepts events only from that senderElastio processes the finding and starts a targeted scanTeams receive recovery-grade intelligenceIncluding:Ransomware detection resultsFile- and asset-level impactLast known clean recovery pointOptional forwarding to SIEM or Security Hub The critical design constraint: trusted senders Each Elastio customer has a dedicated Receiver EventBus. For security reasons, that receiver only accepts events from a single allowlisted Sender EventBus ARN. This design ensures: Strong tenant isolationNo event spoofingClear security boundaries To support scale, customers can route many GuardDuty sources (multiple accounts, regions, or security setups) into that single sender bus. Elastio enforces trust at the receiver boundary. End-to-End Flow Step 1: GuardDuty detects malware GuardDuty identifies a malicious file or suspicious activity in S3 or EC2 and emits a finding. Step 2: EventBridge routes the finding Native EventBridge integration allows customers to filter and forward only relevant findings. Step 3: Sender EventBus enforces trust All GuardDuty findings flow through the designated sender EventBus, which represents the customer’s trusted identity. Step 4: Elastio receives and buffers events The Elastio Receiver EventBus routes events into an internal queue for resilience and burst handling. Step 5: Elastio validates recovery data Elastio maps the finding to impacted assets and initiates scans that analyze both malware indicators and ransomware encryption signals. Step 6: Recovery-grade results Teams receive actionable results: Ransomware detectionFile-level impactLast known clean recovery pointOptional forwarding to SIEM or Security Hub What This Enables for Security and Recovery Teams By combining GuardDuty and Elastio, organizations gain: Faster response triggered by high-signal findingsEarly detection of ransomware encryption inside backupsReduced downtime and data lossConfidence that restores will actually workAudit-ready evidence for regulators, insurers, and leadership Supported Today S3 malware findingsEC2 malware findings EBS-specific handling is in progress and will be added as it becomes available. Why This Matters in Practice In most ransomware incidents, the challenge isn’t identifying a security signal - it’s understanding whether that signal corresponds to meaningful data impact, and what it implies for recovery. Security and infrastructure teams often find themselves piecing together information across multiple tools to assess whether encryption or corruption has reached backups or replicated data. That assessment takes time, and during that window, recovery decisions are delayed or made conservatively. By using GuardDuty findings as a trigger for integrity validation, customers introduce earlier visibility into potential data impact. When suspicious activity is detected, Elastio provides additional context around whether recovery assets show signs of encryption or corruption, and which recovery points appear viable. This doesn’t replace incident response processes or recovery testing, but it helps teams make better-informed decisions sooner, particularly in environments where fileless techniques and identity-based attacks limit the effectiveness of traditional malware scanning. Extending GuardDuty From Detection Toward Recovery Readiness GuardDuty plays a critical role in surfacing high-confidence security findings. Elastio extends that signal into the recovery domain by validating the integrity of data organizations may ultimately depend on to restore operations. Together, they help teams bridge the gap between knowing an incident may have occurred and assessing recovery readiness, with supporting evidence that can be shared across security, infrastructure, and leadership teams. For organizations already using GuardDuty, this integration provides a practical way to connect detection workflows with recovery validation without changing existing security controls or response ownership. Watch our discussion: Understanding Elastio & AWS GuardDuty Malware Scanning for AWS Backup An open conversation designed to answer customer questions directly and help teams understand how these technologies work together to strengthen recovery posture. How signature-based malware detection compares to data integrity validationReal-world scenarios where behavioral and encryption-based detection mattersHow Elastio extends visibility, detection, and recovery assurance across AWS, Azure, and on-prem environmentsAn early look at Elastio’s new integration launching at AWS re:Invent

Hunting and Defeating EDR-Evading Threats and Machine-Identity Attacks As enterprises accelerate cloud transformation, containerization, AI adoption, microservices, and automation, a subtle yet profound shift is reshaping the cyber threat landscape. Traditional endpoint-based detection approaches are no longer sufficient. Attackers are increasingly evading EDR, while simultaneously exploiting a rapidly expanding universe of machine identities such as service accounts, certificates, API keys, and ephemeral workload tokens. This creates a new, invisible attack surface that is often unmonitored, ungoverned, and misunderstood. To defend effectively, organizations must evolve. The new model brings together endpoint awareness, identity intelligence, and data-layer resilience to expose threats that would otherwise remain invisible. The EDR Blind Spot Is Widening Endpoint Detection and Response has been the backbone of enterprise defense. But adversaries have learned to systematically bypass it through techniques that interfere with telemetry, suppress alerts, operate from memory, or shift their activity into systems or layers where EDR agents cannot run. Some threat groups have deployed tooling that disables endpoint monitoring components entirely, allowing operations to continue with little or no visibility for defenders. At the same time, many critical infrastructure components do not support EDR at all. Hypervisors, storage appliances, virtual machine management systems, and specialized cloud services often sit outside traditional endpoint protections. Attackers increasingly target these layers because activity there blends in with normal operations and rarely triggers alarms. As a result, relying solely on endpoint-centric detection creates blind spots that grow wider as modern infrastructure becomes more distributed. The Explosion of Machine Identities and the Risks They Introduce While EDR evasion grows more sophisticated, another trend has emerged in parallel: the exponential rise of machine identities. These are non-human actors created by automation pipelines, containers, microservices, serverless functions, AI agents, DevOps tooling, and cloud services. Machine identities now outnumber human identities in most cloud-forward enterprises by enormous margins. They often carry privileged permissions, access sensitive data paths, or control critical infrastructure functions. Unlike human accounts, these identities rarely follow standardized onboarding, governance, audit, or lifecycle processes. Many are short-lived, created and destroyed automatically, leaving gaps in visibility. Others live far longer than intended because no one realizes they still exist. Attackers increasingly target these identities because compromising one can grant immediate and legitimate access to high-value systems or data. The activity of a hijacked machine identity blends in naturally with expected automation patterns, making detection difficult. In many cases, the identity itself becomes the persistence mechanism. Identity Becomes the New Perimeter These dynamics undermine a core assumption behind many security architectures: that identity governance is equivalent to human access control. In cloud-native enterprises, identity is now as much about workloads as it is about people. When machine identities are not continuously monitored, governed, and validated, they become powerful tools for stealthy lateral movement or data manipulation. This means identity has truly become the perimeter. But it is a perimeter that cannot be secured solely with human-centric tools. The Data Layer Is Where Invisible Threats Finally Become Visible Machine identities interact with data continuously. They create snapshots, move objects across storage tiers, generate logs, trigger analytics pipelines, replicate datasets, and run unattended processes. If one of these identities is compromised, the first signs of malicious activity often appear in the data layer itself. Unauthorized reads, unexpected modifications, corruption of snapshots, tampered metadata, irregular replication events, or the introduction of malicious content are often the earliest and most reliable indicators of attack. By the time endpoint or identity systems raise alerts, the attacker may have already altered data across multiple systems. This is why modern cyber resilience depends on the ability to continuously verify the integrity, security, and recoverability of data itself. A Modern Defense Model Addressing these emerging threats requires a multi-layered approach that blends identity, workload, and data-centric controls. First, all machine identities must be governed with the same rigor as human identities. This means complete inventory, lifecycle management, least-privilege enforcement, short-lived credential use, and continuous monitoring of identity behavior.Second, detection must expand beyond endpoints. Organizations need visibility into identity issuance, API usage, workload behavior, cloud control-plane activity, and infrastructure components that do not support traditional EDR.Third, data integrity must be continuously validated. Snapshots, backups, object data, and replicated datasets must be automatically and regularly inspected. Any unauthorized change or anomaly should be treated as a leading indicator of potential compromise.Fourth, Zero Trust principles must be deeply embedded in the machine and data layers. Verification is no longer only about authenticating a user. It is about verifying the legitimacy of every process, every identity, and every piece of data flowing through the enterprise. Why This Approach Is Strategic Adversaries are adapting quickly. They no longer need to compromise a human identity or bypass every endpoint. They can operate quietly within automation systems, exploit permissions given to machine identities, or target data itself as the first point of manipulation. By addressing machine identity governance and data integrity together, organizations reduce the inherent weaknesses of endpoint-only detection. They gain a defensive architecture that detects threats earlier, responds more effectively, and ensures business continuity even under active attack. The combination of EDR evasion and machine-identity exploitation represents one of the most significant emerging risks to modern enterprises. Attackers are learning to operate invisibly, bypassing traditional controls and embedding themselves in the automation and data layers where detection is weakest. To win in this environment, security teams must shift their mindset. They must unmask the invisible by looking where attackers now hide: in identities, in the control plane, and in the data itself. They must verify continuously, trust nothing implicitly, and safeguard the integrity of the information the business depends on. This is how modern organizations stay resilient. It is how they transform uncertainty into strength. And it is how they defeat adversaries who no longer need to be seen to be dangerous. This is the gap Elastio is built to close. Schedule a review. 3 Key Takeaways EDR alone leaves growing visibility gapsMachine identities are the new attack surfaceData integrity becomes the ultimate detection layer