# WannaCry (2017)
On May 12, 2017, a ransomware worm named WannaCry began propagating across the internet at a speed and scale that had never been seen before. Within four days it had infected more than 200,000 systems in over 150 countries, shutting down hospitals, telecommunications providers, logistics networks, and government agencies with no discrimination between sectors or borders. The attack remains the most geographically widespread ransomware event in recorded history.
WannaCry was not a sophisticated adversary campaign of patience and stealth. It was a blunt instrument: a self-replicating worm armed with a leaked National Security Agency exploit, deployed against a global population of organizations that had simply failed to apply a patch that had been publicly available for two months. That gap, measured in weeks, is what turned a criminal ransomware payload into a global crisis.
The U.S. government, along with the UK, Australia, Canada, and New Zealand, formally attributed WannaCry to the Lazarus Group, a threat actor operating on behalf of North Korea's Reconnaissance General Bureau, in December 2017 and through 2018.
Stage 1: The exploit (EternalBlue and DoublePulsar)
WannaCry's propagation engine was built on two tools stolen from the NSA's Equation Group by a threat actor calling itself Shadow Brokers. EternalBlue exploited a critical vulnerability in Microsoft's implementation of the Server Message Block version 1 (SMBv1) protocol, tracked as MS17-010. The vulnerability allowed an unauthenticated remote attacker to execute arbitrary code on any Windows system with SMBv1 enabled and port 445 exposed.
DoublePulsar was a kernel-mode implant, also from the NSA toolkit, used as a backdoor installer. Once EternalBlue achieved remote code execution, DoublePulsar was injected into the target system's kernel. From there it loaded the WannaCry payload.
Microsoft had released a patch for MS17-010 in March 2017 (Security Bulletin MS17-010), two months before WannaCry launched. Shadow Brokers had published the stolen exploits in April 2017, narrowing the window further. Organizations had every opportunity to close this vulnerability before it was weaponized.
Stage 2: Self-propagation (no user interaction required)
Unlike traditional ransomware that depended on a user clicking a phishing link or opening a malicious attachment, WannaCry propagated as a worm with no human interaction required. Once executing on an infected host, the worm spawned threads that continuously scanned both internal network ranges and random external IP addresses for systems with port 445 open. Any reachable system still running SMBv1 became a new victim, which then became a new scanner. This network-level replication loop is what compressed what would normally be a weeks-long infection campaign into four days.
Stage 3: Ransomware payload
After establishing itself on a new host, WannaCry encrypted files using RSA-2048 and AES-128, appended the .WNCRY extension, and demanded a ransom of $300 to $600 worth of Bitcoin. The ransom note threatened to double the demand after three days and delete files after seven. In practice, the decryption mechanism was poorly implemented and many victims who paid received no working decryptor.
Stage 4: The kill switch (accidental containment)
Marcus Hutchins, a malware researcher better known as MalwareTech, was analyzing WannaCry samples on May 12 when he noticed the malware queried a long, nonsensical domain name before executing its main payload. This was a sandbox-detection technique: some malware analysis environments intercept all DNS queries and return a response, so malware authors design their code to check for a specific domain that should not exist in the real world. If the domain resolves, the malware assumes it is inside a sandbox and terminates.
Hutchins registered the domain for $10.69 and pointed it to a sinkhole server. Within hours, new WannaCry infections worldwide stopped propagating. The global spread was not halted by a government agency or a vendor patch rollout; it was stopped by a researcher spending the cost of a fast food meal. This underscores both how fragile the attacker's design was and how narrow the margin of containment had been.
Root cause 1: Organizations did not apply a publicly available patch
Microsoft issued MS17-010 on March 14, 2017. WannaCry launched on May 12, 2017. Organizations had 59 days to patch. Many did not. In enterprise environments, patch management is often constrained by change control windows, compatibility testing cycles, and the inertia of large IT estates. These processes exist for good reasons, but they create exposure windows that adversaries exploit. A two-month window for a critical remote code execution vulnerability is unacceptable under any reasonable risk posture.
Root cause 2: SMBv1 was still enabled across enterprise networks
SMBv1 is a protocol that dates to the 1980s. Microsoft had been actively deprecating it for years before WannaCry, publishing guidance on disabling it as far back as 2014. Despite this, the protocol remained enabled by default on older Windows versions and was left active in countless enterprise environments due to compatibility dependencies with legacy applications, shared drives, and printers. The risk of legacy protocol exposure is structural: protocols designed before modern threat models existed carry vulnerabilities that are often not worth patching because the protocol itself should be retired.
Root cause 3: Legacy operating systems that could not be patched
The UK National Health Service suffered some of the most visible and devastating WannaCry damage. Hundreds of NHS trusts were affected. An estimated 19,000 appointments were cancelled. Ambulances were diverted. Surgical procedures were postponed because clinical staff could not access patient records. A significant factor in NHS exposure was the continued use of Windows XP across clinical workstations. Windows XP had reached end of support in April 2014. Microsoft did not provide the MS17-010 patch for Windows XP through normal update channels (it released a special emergency patch after WannaCry launched). Organizations running end-of-life operating systems in clinical or operational environments carry structural vulnerability that no amount of monitoring compensates for.
Root cause 4: Government-developed offensive capability became criminal infrastructure
EternalBlue was created by the NSA's Equation Group as an offensive intelligence capability. It was stolen by Shadow Brokers, an entity with suspected ties to Russian intelligence, and released publicly in April 2017. Less than a month later, North Korea's Lazarus Group had weaponized it into WannaCry. The pipeline from NSA development to global ransomware took under a year. This raises a structural question about offensive cyber capability stockpiling that governments have not fully resolved: every exploit developed and retained represents a potential liability if it escapes into the wild.
The financial damage estimate from WannaCry ranges from $4 billion to $8 billion globally, depending on the methodology and what costs are included (ransom payments, remediation, lost productivity, and downstream economic effects). The actual ransom collected was relatively modest: approximately $140,000 worth of Bitcoin, reflecting the poor conversion rate of indiscriminate worm-based ransomware compared to targeted campaigns.
The NHS impact was the most viscerally human consequence. Patients were turned away from emergency departments. Surgical teams could not access imaging. General practitioners could not view prescription histories. The disruption lasted days in many trusts and exposed the degree to which patient safety now depends on IT availability.
Russia's Telefonica, FedEx subsidiary TNT Express, Deutsche Bahn, and Renault-Nissan were among the major corporate victims. In several cases, manufacturing lines were halted when infected systems locked out industrial control connections.
Microsoft took the unusual step of publicly criticizing the NSA for retaining the EternalBlue vulnerability, calling for a "Digital Geneva Convention" governing government offensive cyber capabilities. The incident accelerated enterprise adoption of patching automation tools and drove widespread SMBv1 disablement across corporate networks.
VSD (Vulnerability and Surface Defense): WannaCry is the definitive case for Continuous Surface Reduction. The attack surface was unambiguous and well-documented: SMBv1 exposure on port 445, an unpatched vulnerability with a two-month-old fix available. Every system running SMBv1 and reachable on the network was an exposed surface. CSR's core mandate is to eliminate surface before attackers reach it. Organizations that had disabled SMBv1 in the preceding years, which many had done following Microsoft's guidance, were not vulnerable regardless of patch status. Surface elimination beats patching speed.
SPH (Security Posture and Hygiene): The NHS case is a textbook example of what Autonomous Posture Command exists to address. End-of-life operating systems, unmanaged patch cycles, and no compensating controls for legacy infrastructure describe a posture that had been in decline for years before WannaCry arrived. APC's premise, that posture must adapt continuously rather than being evaluated at point-in-time audit cycles, is the direct counter to the NHS's failure mode. An adaptive posture system would have flagged Windows XP endpoints, SMBv1 enablement, and open port 445 exposure as critical posture deficiencies requiring immediate remediation or isolation.
TID (Threat Intelligence and Defense): The Shadow Brokers leak in April 2017 was a threat intelligence event. Organizations with active threat intelligence programs were aware that stolen NSA exploits targeting SMBv1 were in the wild three weeks before WannaCry launched. Predictive Defense Intelligence's mandate is to anticipate threats before they materialize into incidents. The intelligence was available. The failure was in translating that intelligence into accelerated patch prioritization.
DPS (Data Protection and Sovereignty): WannaCry encrypted data and held it for ransom. For organizations with backup architectures aligned to Sovereign Data Protocol principles, including immutable offsite backups and tested recovery procedures, WannaCry was an operational disruption rather than a data loss event. For organizations without those protections, encrypted files meant real data loss. The distinction between disruption and catastrophe in a ransomware scenario is almost entirely determined by backup architecture quality.