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Device-Bound Sessions

Make Every Web Session Device-Bound

A stolen session token is a working login on the attacker's device — no password, no MFA prompt. cside keeps every session tied to the device that started it, then flags and ends any session that turns up somewhere else. See why 0 of 43 major banks bind the live web session.

This device
Session bound
DeviceMacBook Pro
BrowserChrome 126
Location New York, US
Token
sess_••••4f2a
replayed
Unknown device
Mismatch
DeviceWindows · unknown
BrowserAnti-detect
Location Proxy · NY
Device mismatch — session blocked
The gap

How valid sessions end up on the wrong device

01 Infostealer logs

Malware on a victim's machine scrapes live session cookies and sells them in bulk. The buyer imports the cookie and is logged straight in — no password, no MFA.

02 Adversary-in-the-middle phishing

Reverse-proxy phishing kits relay the real login page, capture the post-MFA session token, and replay it. MFA is satisfied at login; the live session is already stolen. See how token theft survives MFA.

03 Residential proxy replay

Attackers route the stolen session through a proxy in the victim's own city to defeat IP and geo checks, so the hijacked session looks local and trusted.

04 Anti-detect browsers

Purpose-built browsers spoof the victim's user agent, fonts, and device signals to make a hijacked session blend in with normal traffic.

05 On-device malware and RATs

Remote-access tooling rides the victim's own device and session, so network-level controls never even see a new location.

WITH CSIDE
  • Tie every session to the device that created it, from a baseline of 100+ browser, device, and network signals.
  • Catch a stolen token the moment it is replayed from a different device, IP, or browser environment.
  • Trigger step-up auth or kill the session before the attacker reaches account or payment data.
  • Works on every browser, pre-login through checkout — first-party, unsampled, no extra user friction.
How it works

How device-bound sessions work

01

Baseline the device at session start

When a session begins, cside captures 100+ signals into a device profile and ties it to the session — the fingerprint a real user reproduces and an attacker can't.

02

Watch the session, not just the login

Every request is checked against the session's device baseline, continuously — not only at the login moment where most tools stop looking.

03

Detect the device mismatch

When a token is replayed from a different device, IP, or browser environment, the profile no longer matches. The shift is visible even before the cookie expires.

04

Step up or shut it down

Feed the mismatch into your auth flow to force re-authentication, or invalidate the session outright — before the attacker touches sensitive data.

Compare

Why cside device-bound sessions outperform the alternatives

vs. MFA & passwords
vs. Device scoring only
vs. DBSC (Chrome-only)
Secures the whole session, not just the login moment Acts on a device mismatch — challenges or kills the session, not just a risk score Protects every browser, not only Chrome
Catches a valid token replayed from the attacker's device Re-checks the device continuously through the session Covers the journey before login too — signup, password reset, checkout
No reliance on the user passing a second factor mid-session Built-in responses: step-up auth or session invalidation One first-party script, unsampled — no new hardware or browser support
FAQ

Questions, answered

01 What does a 'device-bound session' actually mean?

It means a session only works on the device that created it. cside builds a device profile when the session starts and checks every request against it. If the same session shows up on another device, that mismatch can trigger a challenge or invalidation — so a stolen cookie on its own is no longer enough to take over the account.

02 How is this different from MFA?

MFA proves who logged in. It does nothing once a session token exists, and stolen tokens are replayed after MFA is already satisfied. Device-bound sessions protect the part MFA leaves open: the live session that follows the login. See why MFA-satisfied does not mean session-secure.

03 Does cside cryptographically bind the token the way DBSC does?

No, and the two solve the problem differently. Google's Device Bound Session Credentials (DBSC) cryptographically tie a cookie to a hardware key, but only on Chrome and only after login. cside uses device intelligence to detect when a session moves to a new device, across every browser and every step of the journey. They are complementary — see DBSC vs. device fingerprinting.

04 How fast does it detect a stolen session?

The device check runs on the session's own requests, so a replay from a different device, IP, or browser environment can be flagged in real time — often well before the stolen cookie would have expired.

05 Will legitimate users get logged out when they change networks or devices?

No. cside scores the whole device profile, not a single signal, so an IP change on the same device reads very differently from a full device swap. You control the threshold and the response — challenge, step up, or invalidate.

06 Which attacks does this stop?

Session hijacking from infostealer logs, adversary-in-the-middle phishing, residential-proxy replay, and anti-detect browsers — the paths that put a valid session on an attacker's device. For the broader threat, see account takeover.

07 Do I need to replace my auth provider?

No. cside runs alongside your existing auth and session layer and sends the device-mismatch signal into your flow, so you decide whether to step up or revoke. It is a layer, not a rip-and-replace.

08 How is it deployed?

With one first-party script. Signals are collected on the first-party path, unsampled, with no measurable latency and without blocking the UI.

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Stop session hijacking

Bind every session to its device

One first-party script. Catch a stolen token the moment it lands on the wrong device.

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