Medium

Microsoft Exchange OWA Spoofing Vulnerability

IdentifiersCVE-2019-0817CWE-345

A spoofing vulnerability in Microsoft Exchange Server affects Outlook Web Access (OWA) when it does not properly handle web requests. The flaw can allow content or requests to be presented in a way that misrepresents their origin or trust context, leading to spoofing. The issue is identified by Microsoft as the Microsoft Exchange Spoofing Vulnerability and is distinct from CVE-2019-0858.

For your environment

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ANALYST BRIEF

Impact, mitigation & remediation

What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.

Impact

What an attacker gets, and what they’ve been doing with it.

Successful exploitation can allow an attacker to spoof trusted content or interfaces presented through OWA, potentially misleading users about the authenticity or origin of web content and enabling follow-on social engineering or credential theft scenarios. The available information does not provide more specific technical impact details beyond spoofing.

Mitigation

If you can’t patch tonight, do this now.

If immediate patching is not possible, reduce exposure of Outlook Web Access to untrusted networks, restrict access to OWA to trusted users and networks where feasible, and monitor for suspicious OWA web request patterns and anomalous authentication activity. These are compensating controls only; the primary mitigation is vendor patching.

Remediation

Patch, then assume compromise.

Apply the Microsoft security updates released for Microsoft Exchange Server on 2019-04-09 that address CVE-2019-0817. Use the vendor-provided patches appropriate to the affected Exchange Server version.

PUBLIC EXPLOITS

Exploits

No public exploits tracked yet. Mallory keeps watching.

VALID 0 / 0 TOTALView more in app

No public exploit code observed for this vulnerability.

EXPOSURE SURFACE

Affected products & vendors

Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.

VendorProductType

Microsoft CorporationExchange Serverapplication

Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.

ACTIVITY FEED

Recent activity

2 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.

2 SOURCESView more in app

msrc microsoftNews

Mar 2, 2021

CVE-2021-27065 - Security Update Guide - Microsoft - Microsoft Exchange Server Remote Code Execution Vulnerability

Specific vulnerability listed in the content with severity Important.

msrc microsoftNews

Mar 2, 2021

CVE-2021-26857 - Security Update Guide - Microsoft - Microsoft Exchange Server Remote Code Execution Vulnerability

Specific named vulnerability listed in the content; no product or technical description is provided beyond severity/date and tabular flags.

What this page doesn’t show

The version that knows your environment.

This page is what’s public. Mallory adds the parts that aren’t: which of your assets are affected, which adversaries are exploiting it right now, which detections to deploy, and what to do tonight.

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Exposure mapping

Query your assets running an affected version, and investigate the blast radius.

Threat actor evidence

Every observed campaign linking this CVE to a named adversary.

Associated malware

Malware families riding this exploit, with evidence and IOCs.

Detection signatures

YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.

Vendor-by-vendor mapping

Cross-references every affected SKU, including bundled OEM variants.

Social activity