Microsoft Outlook Improper Input Validation Vulnerability
Microsoft · Office Outlook
A flaw in Microsoft Office Outlook stems from improper input validation, which allows remote code execution. An unauthenticated attacker with network access can exploit it without any user interaction and under the default configuration, potentially gaining full control over the affected system.
Microsoft Outlook Remote Code Execution Vulnerability
- Exploited
- Yes, in CISA KEV
- Reports
- 0
- Tactics
- 2/15
How an attack unfolds
Based on MITRE ATT&CKA public catalogue of the techniques attackers use, maintained by MITRE. Patchfirst uses it to describe what attackers do with a vulnerability. mappings. Select a step to see the evidence.How attackers get in
What they do
Exploitation timelineDated milestones for a CVE: when it was disclosed, when exploit code became public, when exploitation was confirmed, and when threat reports named it.
First seen exploited 3 months after disclosure. Public exploit code (PoC-in-GitHub) appeared 2 days after disclosure.
- Disclosedday 0
- Public exploit codePoC-in-GitHub+2 days
- First seen exploitedVulnCheck KEV evidence+3 mo
- Added to CISA KEVEU database agrees+12 mo
CISA KEV listing is when exploitation was confirmed, not necessarily the first attack.
MITRE ATT&CKA public catalogue of the techniques attackers use, maintained by MITRE. Patchfirst uses it to describe what attackers do with a vulnerability. techniques
2 TechniqueOne specific attacker behaviour in MITRE ATT&CK, such as T1190 “Exploit Public-Facing Application”. IDs with a dot, like T1059.004, are sub-techniques., grouped by TacticThe attacker’s goal at a stage of an attack in MITRE ATT&CK, such as Initial Access or Persistence. Each technique belongs to one or more tactics. in kill-chain order 2Initial AccessTA0001
Attackers can send a specially crafted email that uses the file:// protocol to reference a server that they own, ending the file:// link with an exclamation mark to bypass Outlook's security features, leading to remote code execution.
ExecutionTA0002
Detection
0 rules for this CVE · 99 general rules for its techniquesRules for this CVE
0Sigma ruleAn open, vendor-neutral detection rule for log data. Security teams convert Sigma rules into searches for their own SIEM. that reference CVE-2024-21413 directly.CVE-specific rules are not available in this build. Search SigmaHQ ↗
General rules for this CVE’s techniques
These detect the technique in general, not this specific vulnerability.
Spearphishing LinkT1566.0024 general rules
- Potential Malicious Usage of CloudTrail System Managerhightest
- Suspicious Execution via macOS Script Editormediumtest
- Suspicious Email Delivered In Microsoft 365mediumexperimental
- EvilTokens PhaaS Kit Phishing Related Request - Proxylowexperimental
Command and Scripting InterpreterT105995 general rules
- HackTool - Sliver C2 Implant Activity Patterncriticaltest
- Lazarus Group Activitycriticaltest
- REvil Kaseya Incident Malware Patternscriticaltest
- Turla Group Lateral Movementcriticaltest
- Windows Defender AMSI Trigger Detectedhighstable
- Windows Defender Threat Detectedhighstable
- Abusable DLL Potential Sideloading From Suspicious Locationhightest
- Add Insecure Download Source To Wingethightest
Sigma rules © SigmaHQ, Detection Rule License 1.1; linked, not reproduced.
What security researchers reported
Not named in any threat report yetAlso mentioned in 50 community threat pulses (AlienVault OTX)
Weaker evidencePulses are indicator collections that anyone can publish. A mention is not confirmation of exploitation.
- Actively_Exploited_Kev | Oct 30, 202629 Oct 2026
- Actively_Exploited_Kev | Oct 29, 202628 Oct 2026
- Actively_Exploited_Kev | Oct 28, 202627 Oct 2026
- Actively_Exploited_Kev | Oct 27, 202626 Oct 2026
- Actively_Exploited_Kev | Oct 24, 202623 Oct 2026
- Actively_Exploited_Kev | Oct 23, 202622 Oct 2026
- 44 more on OTX