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CyberDudeBivash ThreatWire — Breaking Cyber Incidents (14-Aug-2025)

 


Executive summary (read first)

  • WinRAR zero-day (CVE-2025-8088) is now in CISA KEV → active exploitation, patch or remove legacy WinRAR immediately. CISANVD

  • Exchange Hybrid flaw (CVE-2025-53786) could let attackers pivot from on-prem to M365; urgent US gov directive + Microsoft guidance. CISA+1

  • Citrix NetScaler (CVE-2025-6543) is actively exploited against critical sectors—verify versions and harden management exposure. The Hacker News

  • Trend Micro Apex One (on-prem): critical RCE; fix tool out, exploitation reported; patch plans required. success.trendmicro.comThe Hacker News

  • Microsoft Patch Tuesday (Aug): 100+ CVEs fixed incl. Kerberos zero-day (CVE-2025-53779) → AD privilege escalation risk. QualysThe Hacker News

  • Law-enforcement hit on BlackSuit/Royal ransomware disrupted infra (~$1M seized) but regrouping likely → watch for TTP overlap. Department of Justice+1

1) Act-now vulnerabilities

A) WinRAR Path Traversal → RCE (CVE-2025-8088) — Exploited in the wild

  • What: Malicious archives can write files outside the intended path → code runs on open/startup.

  • Scope: Windows WinRAR ≤ affected builds.

  • Why urgent: Listed in CISA KEV (federal agencies must remediate). CISA
    Actions (today):

  1. Update to the latest fixed WinRAR release or remove WinRAR.

  2. Block .rar/.zip from untrusted senders at email/web gateway; open archives in sandbox.

  3. Hunt for suspicious file writes from WinRAR.exe to startup locations. NVD

Elastic KQL (IOC starter):

process.name: "WinRAR.exe" and
file.path:("C:\\Users\\*\\AppData\\Roaming\\Microsoft\\Windows\\Start Menu\\Programs\\Startup\\*" 
           "C:\\ProgramData\\Microsoft\\Windows\\Start Menu\\Programs\\StartUp\\*")

B) Microsoft Exchange Hybrid Priv-Esc (CVE-2025-53786)

  • What: Trust misconfiguration in hybrid joins lets an attacker with on-prem Exchange admin escalate in EXO/M365.

  • Status: CISA directive + MS guidance; apply April 2025 fixes, move to Exchange Hybrid Agent, rotate creds, run Health Checker. CISA+1
    Actions (today):

  1. Identify all hybrid servers; run Exchange Health Checker; enable Service Principal Clean-up Mode.

  2. Rotate SPN/app secrets; review audit logs for unusual EXO operations sourced via on-prem Exchange.

  3. Segregate Exchange mgmt from Internet; enforce MFA + PAWs for admins.

Sentinel (KQL) hunt idea:

AuditLogs
| where Operation in ("Add-MailboxPermission","Set-RoleGroup","Add-ApplicationAccessPolicy")
| where ResultStatus == "Success"
| extend Source=AdditionalDetails

C) Citrix NetScaler ADC/Gateway (CVE-2025-6543) — Active exploitation

  • What: Critical flaw exploited pre-disclosure; observed targeting in NL critical orgs. The Hacker News
    Actions (today):

  1. Patch to fixed builds; restrict mgmt plane by IP/VPN; review for webshells.

  2. Rotate any secrets stored on devices; check NetScaler/AAA logs for anomalies.

D) Trend Micro Apex One (on-prem) RCE

  1. Run the vendor fix tool; schedule maintenance to patch once GA.

  2. Isolate console to mgmt VLAN; review admin account changes and web access logs.

2) Patch Tuesday — Focus items

  • Microsoft shipped fixes for 111+ CVEs, incl. Kerberos P.E. zero-day (CVE-2025-53779) enabling AD takeovers if chained. Prioritize domain controllers, Kerberos components, and edge services. QualysThe Hacker News

Domain controller detection (EDR rule ideas):

  • Alert on ticket-granting anomalies from non-standard hosts.

  • Monitor for klist, rubeus, unusual LSASS access.

3) Campaigns & ecosystem

BlackSuit/Royal ransomware disruption

  • DOJ seized servers/domains and ~$1M; expect re-branding and TTP reuse. Update blocklists, but defend against behaviors, not names. Department of Justice+1

4) CyberDudeBivash guidance — 72-hour action plan

0–24h

  • Push emergency updates (WinRAR removal/update; Exchange hybrid mitigations; NetScaler patches; Trend Micro fix tool).

  • Block outbound SMB/WebDAV from user segments; tighten email/archive policies.

24–48h

  • Run token/session hygiene (revoke stale sessions; enforce WebAuthn for admins).

  • Threat hunts: WinRAR startup artifacts; Exchange role/permission changes; NetScaler webshell sweep; Apex One admin actions.

48–72h

  • Tabletop: “Archive-delivered RCE → ransomware” and “Hybrid Exchange pivot to EXO.”

  • Finalize SOAR playbooks → isolate host, revoke tokens, disable accounts, open IR case with evidence.

5) Sector impact snapshot

  • Public sector/critical infra: NetScaler exploitation risk and Exchange hybrid exposure. The Hacker NewsCISA

  • Enterprises & SMBs: WinRAR and Apex One are common; user-originated RCE → ransomware pathways. CISAsuccess.trendmicro.com

6) Quick copy for your internal alert (paste & send)

Subject: URGENT: Patch WinRAR, Exchange Hybrid, Citrix NetScaler; apply Trend Micro fix
Why: Active exploitation + zero-day risk.
Do now: Remove/update WinRAR; apply Exchange hybrid guidance; patch NetScaler; run Trend Micro fix; monitor for unusual mail flow and startup artifacts.

From the Founder

Our goal at CyberDudeBivash is simple: compress attacker dwell time with clear, operator-ready actions. If you need help validating exposure or running the hunts above, we’re ready.

— Bivash Kumar Nayak, Founder, CyberDudeBivash

More daily intel: cyberdudebivash.com

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