Account Takeover Prevention
Stop account takeover before it starts.
Constella delivers continuous, verified visibility into stolen credentials, exposed passwords, and infostealer-harvested session data, giving fraud, security, and identity teams the pre-attack intelligence to shut down ATO campaigns before the first unauthorized login.
How does Constella help prevent account takeover?
Account takeover is a credential problem, and credentials have never been more exposed. In 2025, 68.89% of all breached credentials were found in plaintext, a 261% year-over-year increase, and 51.7 million infostealer packages were traded on criminal markets, each containing the harvested passwords, session cookies, and autofill data of compromised devices. Constella prevents account takeover by detecting these exposures the moment they appear on the Surface, Deep, and Dark Web, delivering verified, pedigreed alerts that allow fraud and security teams to force credential resets, invalidate active sessions, and block compromised accounts before attackers can authenticate. Unlike raw data broker feeds that flood dashboards with stale, recycled records, Constella’s intelligence is deduplicated, source-verified, and current, enabling high-confidence action rather than endless triage.
Industry Focus
The ATO Threat Has Industrialized
Account takeover is no longer a targeted attack executed by skilled adversaries: it is an industrialized, automated operation. The same Agentic AI systems that defenders use to scale their security operations are being mirrored by threat actors to automate the entire ATO lifecycle: credential validation, account access, fraud execution, and lateral movement, at machine speed, across millions of targets simultaneously.
The Plaintext Crisis
Constella’s 2026 Identity Breach Report found that 68.89% of all breached credentials in 2025 were exposed in plaintext, representing a 261% year-over-year increase. This is not a decline in organizational security hygiene — it reflects the industrialization of adversarial tradecraft. Infostealers harvest credentials directly from browser memory after authentication, bypassing hashing entirely. GPU-accelerated cracking farms convert historically hashed credentials into actionable plaintext libraries. The result: attackers move directly from credential acquisition to automated account takeover with no intermediate decryption step.
The Infostealer Surge
51.7 million infostealer packages were processed by Constella in 2025 — a 72% increase year-over-year — identifying 24.8 million unique infected devices. Of those packages, 98.6% contained active passwords and 99.54% included the specific URLs where those credentials were used, giving attackers a precise, pre-mapped roadmap to the accounts they want to access. Session cookies embedded in these packages allow attackers to bypass MFA entirely by replaying an already-authenticated session.
The Credential Density Problem
While unique emails in Constella’s data lake grew by only 11% in 2025, total curated records grew by 135%. This means attackers now hold an average of six distinct data points per identity — multiple passwords, associated usernames, device signals, and location history — enabling AI-driven password prediction and composite identity attacks that go far beyond simple credential stuffing.
The Speed Problem
Password exposure grew 77.1% year-over-year in 2025, driven by an obsessive adversarial focus on authentication bypass. Stolen credentials are validated and weaponized within hours of acquisition. Traditional breach notification timelines — days or weeks after the event — leave an enormous window in which ATO campaigns can run undetected and unchallenged.
How Constella Helps
Constella closes the gap between credential exposure and organizational response, delivering the pre-attack visibility that fraud and security teams need to act before attackers succeed. Our intelligence covers the full credential exposure lifecycle, from the moment a password appears in a breach repository through active infostealer harvesting and dark web trading.
Real-Time Credential & Breach Monitoring
Continuous monitoring of corporate domains and individual user identities across breach repositories, paste sites, combo lists, and dark web credential markets. When a monitored identity appears in a new breach or credential compilation, Constella generates an alert with verified source attribution, exposure recency, and plaintext credential confirmation where available — enabling precise, targeted remediation rather than disruptive broad resets.
Infostealer Detection & Session Compromise Alerting
When a corporate email, customer account, or monitored domain appears in a newly ingested infostealer package, Constella alerts immediately — including which specific applications had active sessions harvested, the infected device’s hardware metadata, and the malware strain responsible. This enables session invalidation before stolen cookies can be replayed to bypass MFA.
Password Exposure Verification
For organizations running automated credential checks at login or account creation, Constella’s password exposure verification capability queries the full identity data lake against any submitted password — returning a verified match or no-match response in real time, with sub-second latency suitable for high-volume transactional environments. Blocks compromised passwords at the point of use, not after the account is already at risk.
Identity Enrichment & Risk Scoring
Enrich any known identity attribute — email address, username, phone number — with additional verified identity attributes drawn from Constella’s 54.6 billion record data lake. Produces high-confidence identity clusters that fraud teams can use to assess account risk, flag suspicious registrations, and prioritize remediation queues based on verified exposure severity rather than raw alert volume.
Verified Data Pedigree — Eliminating ATO Alert Fatigue
Raw credential feeds generate thousands of alerts per week, most of which are stale, recycled records from years-old breaches. Constella’s pedigree process deduplicates, timestamps, and source-verifies every record before it reaches the analyst — reducing alert volume to a manageable, high-confidence queue that enables decisive action rather than exhausting triage.
Hunter Investigative Platform for ATO Attribution
When an ATO campaign is suspected or detected, Hunter allows fraud analysts and security investigators to pivot from a single compromised account to the full threat actor operation — identifying which criminal marketplace the credentials were sourced from, which other accounts in the organization may be at risk from the same campaign, and the broader identity cluster of the actor behind the attack.
Product Alignment: The ATO Prevention Toolkit
Case Studies: Account Takeover Prevention in Action
Case Study 1
Regional Bank Stops an Automated Credential Stuffing Campaign Targeting 14,000 Customer Accounts
The Organization: Regional retail bank, 1.2 million consumer account holders.
The Challenge: An automated credential stuffing tool was being used against the bank’s online banking portal. Thousands of authentication attempts per hour were being generated using credentials sourced from a recent third-party breach — but the bank had no visibility into which specific credentials were compromised or which customer accounts were immediately at risk.
The Solution: Integrated Constella’s credential monitoring and password exposure verification into the bank’s fraud operations workflow. Constella identified the specific breach event sourcing the attack within hours, surfaced which customer email addresses had appeared in the compromised dataset, and enabled the fraud team to proactively lock and reset the targeted accounts before unauthorized access succeeded.
The Result: 14,000 at-risk customer accounts identified and proactively remediated before any unauthorized access. The credential stuffing campaign — which had generated 47,000 login attempts in a 6-hour window — was neutralized by removing the valid credentials from the attacker’s playbook. Zero confirmed account compromises resulted from the campaign.
Case Study 2
Global E-Commerce Platform Reduces Account Takeover Losses by Integrating Real-Time Infostealer Intelligence into Fraud Decisioning
The Organization: Global e-commerce platform, 40 million active customer accounts across 18 countries.
The Challenge: A sustained ATO campaign was generating significant fraud losses through gift card fraud, unauthorized purchases, and account resale on criminal markets. The platform’s existing fraud model was optimized for behavioral anomaly detection — but it could not distinguish between a legitimate user authenticating from a new device and an attacker replaying a stolen infostealer session cookie from the same geographic region as the account owner.
The Solution: Integrated Constella’s infostealer monitoring and identity intelligence API into the platform’s fraud decisioning layer. Constella’s continuous monitoring flagged accounts whose associated credentials or session data had appeared in recent infostealer packages, enriching the fraud model’s risk score with a verified, external identity risk signal before authentication was approved.
The Result: ATO-driven fraud losses fell by 38% in the first quarter following integration. The fraud model’s false positive rate improved — because the Constella risk signal added genuine differentiation between anomalous-but-legitimate logins and credential-compromised account access attempts. The platform extended the integration to flag suspicious new account registrations using known-compromised email addresses, reducing synthetic identity fraud exposure as a secondary benefit.
The Constella Difference for Account Takeover Prevention
FAQs
Credential stuffing is an attack method — the automated injection of stolen username and password pairs into login forms to identify valid credentials. Account takeover is the outcome — unauthorized control of a user’s account following successful authentication with compromised credentials. Credential stuffing is the most common initial access method for ATO, but attackers also use infostealer-harvested session cookies (which bypass MFA by replaying an already-authenticated session), phishing, and SIM swapping. Constella addresses all credential-based ATO vectors by monitoring for the underlying identity exposures that enable each attack type.
Password resets address the password — but not the session. When an infostealer harvests an active session cookie from a compromised device, the attacker possesses a token that authenticates them without requiring a password at all. Resetting the password does not invalidate existing sessions. Constella’s infostealer monitoring detects session cookie compromise specifically, enabling targeted session invalidation alongside credential resets — closing both vectors simultaneously. Additionally, because nearly 60% of breach datasets are recycled credential compilations, the same compromised password may resurface in multiple successive breach releases even after an initial reset, requiring continuous monitoring rather than one-time remediation.
False positives in ATO detection typically occur when a fraud model flags legitimate anomalous behavior — a user logging in from a new device, a new location, an unusual time — without external context confirming whether that account is genuinely at risk. Constella’s verified identity intelligence provides that external context: when a Constella alert confirms that a specific account’s credentials appeared in a recent infostealer package, the fraud model has high-confidence signal that this account represents an elevated-risk login attempt. Conversely, when no Constella exposure exists for an account, the model can deprioritize behavioral anomalies with greater confidence. This two-directional enrichment reduces both false positives (legitimate logins incorrectly blocked) and false negatives (compromised logins incorrectly approved).
Constella’s Identity Intelligence API is a RESTful service designed for straightforward integration into existing fraud decisioning platforms, identity providers, and security tooling. Sub-second latency supports real-time use cases — authentication enrichment, account creation risk scoring, password reset validation — without introducing meaningful friction to the user flow. Pre-built integrations are available for identity providers including Okta and Microsoft Entra ID. For custom environments, Professional Services are available to scope and support integration design.
Constella’s 2026 Identity Breach Report identified e-commerce and retail as the highest-volume breach target by sector in 2025, with a 239% year-over-year increase in verified breaches — driven primarily by infostealer activity harvesting customer payment data and session cookies for automated ATO. Financial services (banking and fintech) saw a 455% increase in verified breaches, reflecting the high-value of financial account access. Healthcare (+303%), technology (+276%), and government (+569%) also saw dramatic growth. Across all sectors, the common thread is the industrialization of credential-based initial access — ATO is no longer a sector-specific risk, it is a universal one.
Yes. Constella’s monitoring capabilities support consumer-scale monitoring across millions of individual user identities — not just corporate domain monitoring for employees. This makes Constella’s intelligence applicable to consumer-facing fraud prevention teams, identity theft protection providers, financial institutions protecting retail banking customers, and e-commerce platforms protecting consumer account holders. Licensing structures are available for OEM, white-label, and direct enterprise deployment depending on the use case and identity volume. Contact your Constella account executive to discuss the appropriate structure for your platform.
Stop account takeover before it starts.
See how Constella’s pre-attack identity intelligence gives fraud and security teams the verified credential visibility to act before attackers succeed.