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Microsoft’s Office365 multi-factor authentication (MFA) can now be bypassed using SessionShark, an adversary-in-the-middle (AiTM) phishing kit that steals session tokens. This attack renders 2FA useless by capturing authenticated session cookies, allowing attackers to hijack accounts without needing the one-time passcode.
Read the full report: SlashNext
You Should Know: How to Detect & Mitigate SessionShark Attacks
1. Detecting Suspicious Activity
Use these commands to monitor session tokens and logins:
Linux (Using `journalctl` for Auth Logs)
journalctl -u ssh --no-pager | grep "Failed password" grep "session opened" /var/log/auth.log
Windows (Check Event Logs for Unusual Logins)
Get-WinEvent -FilterHashtable @{LogName='Security'; ID=4624, 4625} | Format-Table -AutoSize
2. Preventing Session Hijacking
- Disable Legacy Authentication (Basic Auth) in Office365:
Set-OrganizationConfig -OAuth2ClientProfileEnabled $true
- Enforce Conditional Access Policies (Azure AD):
New-AzureADPolicy -Definition @('{"ConditionalAccess":{"Enabled":true}}')
3. Monitoring Network Traffic for AiTM Attacks
Use Wireshark or tcpdump to detect unusual redirects:
tcpdump -i eth0 'port 443 and (tcp[((tcp[12:1] & 0xf0) >> 2):4] = 0x47455420)'
4. Revoking Stolen Sessions
In Azure AD, force sign-out all sessions:
Revoke-AzureADUserAllRefreshToken -ObjectId (Get-AzureADUser -SearchString "[email protected]").ObjectId
What Undercode Say
SessionShark proves that MFA alone isn’t enough—attackers evolve. Defenses must include:
– FIDO2/WebAuthn (phishing-resistant MFA)
– Network segmentation (restrict Office365 traffic)
– Behavioral analytics (UEBA tools)
– Strict cookie policies (HttpOnly, `Secure` flags)
Linux Admins: Use `fail2ban` to block brute-force attempts:
fail2ban-client set sshd banip <ATTACKER_IP>
Windows Admins: Enable LSA Protection against token theft:
New-ItemProperty -Path "HKLM:\SYSTEM\CurrentControlSet\Control\Lsa" -Name "RunAsPPL" -Value 1 -Force
Expected Output: A hardened environment where session hijacking is detected early and mitigated.
Related Links:
References:
Reported By: Charlescrampton Microsofts – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
