Microsoft Entra ID Session Token Theft and Replay
Session token theft (also called token replay or pass-the-cookie) is one of the most prevalent identity attacks targeting Microsoft 365 and Entra ID in 2025-2026. Adversaries use adversary-in-the-middle (AiTM) proxy frameworks (Evilginx2, Modlishka, Muraena, Tycoon 2FA, EvilProxy) to intercept valid session cookies from M365 sign-in flows, then replay those cookies to authenticate as the victim without needing their credentials or MFA code. The attack works because Microsoft's authentication cookies are bound to the browser session but not to the originating IP — replaying the cookie from a different IP is detected by Entra ID's risk engine but is not blocked by default. Scattered Spider and Storm-0539 are documented using this technique at scale against SMBs and mid-market organisations, primarily targeting financial fraud (payment diversion, payroll fraud) and IT admin compromise to then facilitate SIM swapping.
// THREAT: Entra ID Session Token Theft & Replay (AiTM)
// Detects session token replay indicators: impossible travel, sign-in after
// MFA followed by no-MFA sign-in, new IP using existing session
// Alert 1: Impossible travel — same user, successful sign-in from two
// geographically distant IPs within a short time window
let MaxTravelTimeMinutes = 60;
let ImpossibleTravel = AADSignInLogs
| where TimeGenerated > ago(24h)
| where Status.errorCode == 0
| where IPAddress != "" and Location != ""
| summarize
SignInTimes=make_list(TimeGenerated),
IPs=make_list(IPAddress),
Locations=make_list(Location),
MFAResults=make_list(tostring(AuthenticationDetails))
by UserPrincipalName
| mv-expand TimeGenerated=SignInTimes, IP=IPs, Location=Locations to typeof(string)
| order by UserPrincipalName, TimeGenerated asc
| extend PrevTime=prev(TimeGenerated), PrevIP=prev(IP), PrevLoc=prev(Location)
| where UserPrincipalName == prev(UserPrincipalName)
| extend TimeDiff = datetime_diff('minute', todatetime(TimeGenerated), todatetime(PrevTime))
| where TimeDiff between (1 .. MaxTravelTimeMinutes)
and Location != PrevLoc
and IP != PrevIP
| project TimeGenerated, UserPrincipalName, IP, Location, PrevIP, PrevLoc, TimeDiff
| extend ThreatType = "ImpossibleTravel_TokenReplay";
// Alert 2: Successful sign-in from IP not associated with the user's last 30 days
// with no MFA performed (token replay bypasses MFA)
let UserIPBaseline = AADSignInLogs
| where TimeGenerated between (ago(30d) .. ago(1d))
| where Status.errorCode == 0
| summarize KnownIPs=make_set(IPAddress) by UserPrincipalName;
AADSignInLogs
| where TimeGenerated > ago(24h)
| where Status.errorCode == 0
| where AuthenticationRequirement =~ "singleFactorAuthentication"
or (AuthenticationDetails !has "MFA" and AuthenticationDetails !has "Passwordless")
| join kind=leftouter UserIPBaseline on UserPrincipalName
| where not(IPAddress in~ (KnownIPs))
| project TimeGenerated, UserPrincipalName, IPAddress, Location,
AppDisplayName, AuthenticationRequirement, AuthenticationDetails,
RiskLevelDuringSignIn, ConditionalAccessStatus
| extend ThreatType = "NoMFA_NewIP_PossibleTokenReplay"Data Sources
Required Tables
False Positives
- Users legitimately travelling who sign in from airports, hotels, or multiple mobile data providers within a short window
- Shared accounts used by multiple team members from different locations (should be eliminated as an SMB practice)
- VPN use that changes apparent location between sign-ins (user connects to VPN on second sign-in but not first)
- Users with MFA remembered on trusted devices who then sign in from a new device without MFA prompt (MFA remembered state is a Conditional Access configuration)
References (5)
- https://www.microsoft.com/en-us/security/blog/2022/07/12/from-cookie-theft-to-bec-attackers-use-aitm-phishing-sites-as-entry-point-to-further-financial-fraud/
- https://www.ncsc.gov.uk/blog-post/phishing-attacks-mitm-proxies
- https://www.crowdstrike.com/blog/scattered-spider-aitm-phishing/
- https://attack.mitre.org/techniques/T1539/
- https://github.com/kgretzky/evilginx2
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