Hackers tried to exploit two zero-days in Trend Micro's Apex One EDR platform

Trend Micro OfficeScan contains a directory traversal flaw (CWE-22) in its handling of ZIP archives: when a zip file is extracted to a designated folder on the OfficeScan server, archive entries can escape that folder, allowing an attacker to place files at exploitable locations and achieve remote code execution. The flaw is triggered by getting the server to extract an attacker-influenced ZIP archive into the specific folder on the OfficeScan server. Successful exploitation yields arbitrary code execution on the OfficeScan management server, which typically holds broad control over the managed endpoint fleet and can serve as a foothold for lateral movement. Any organization running an on-premises Trend Micro OfficeScan deployment is affected; the source data does not specify affected version ranges. The vulnerability was added to the CISA KEV catalog on 2021-11-03 (indicating observed exploitation, with ransomware use unknown), and EPSS assigns a 25.1% probability of exploitation within 30 days (98th percentile); no public PoC is known.

Do: Apply Trend Micro's updates per vendor instructions, as required by CISA's KEV listing, and verify the patched build against Trend Micro's advisory since specific version numbers are not provided here (note that OfficeScan was succeeded by Trend Micro Apex One, so confirm patched status on migrated installs). Inventory for internet-exposed OfficeScan/Apex One management consoles and restrict access to trusted networks, and hunt for evidence of exploitation given the confirmed in-the-wild status.

Trend Micro Apex One, OfficeScan, and Worry-Free Business Security 10.0 SP1 on Microsoft Windows contain an improper access control flaw that lets an attacker manipulate a specific product folder to temporarily disable the security product and abuse a Windows function to escalate privileges. The attacker must first obtain the ability to execute low-privileged code on the target system; Windows 10 version 1909 (OS Build 18363.719) mitigates the hard-link technique, so earlier Windows versions are the easier targets. Successful exploitation yields local privilege escalation with high impact on confidentiality, integrity, and availability (CVSS 3.1: 7.8). Any organization running these Trend Micro endpoint agents on unpatched Windows machines is affected, with exposure driven by fleet size rather than internet-facing services. The vulnerability is being exploited in the wild per vendor advisories and news coverage, and CISA added it to the KEV catalog on 2021-11-03 with the required action of applying vendor updates; no public proof-of-concept is documented.

Do: Apply Trend Micro's patched builds for Apex One and Worry-Free Business Security 10.0 SP1 per the vendor advisory, as CISA's required action directs. Prioritize hosts running Windows versions older than Windows 10 1909 (OS Build 18363.719), where the hard-link mitigation is absent, and verify no unpatched agents remain in your fleet. Also check endpoints for signs of prior low-privileged code execution and local privilege escalation, since the flaw requires an existing foothold to exploit.

CVE-2020-8467 is a remote code execution flaw in the migration tool component of Trend Micro Apex One (2019) and OfficeScan XG, exploitable by remote attackers who already hold valid low-privileged credentials. Because the attack vector is network-based with no user interaction, an authenticated attacker can send crafted input to the migration tool component and execute arbitrary code on the affected installation, with high impact on confidentiality, integrity, and availability. Any organization running the on-premises Apex One (2019) or OfficeScan XG endpoint security platforms is potentially affected. The flaw is being exploited in the wild: CISA added it to the Known Exploited Vulnerabilities catalog on 2021-11-03, its EPSS score of 10.8% (96th percentile) signals meaningful near-term exploitation risk, and news reports describe attackers actively attempting to exploit it and a companion Apex One zero-day.

Do: Apply the latest Trend Micro critical patch for Apex One (2019) and OfficeScan XG per the vendor's security bulletin, as required by the CISA KEV listing. Because exploitation requires valid credentials, audit accounts on the Apex One/OfficeScan management console for compromise or weak passwords, review logs for unexpected requests involving the migration tool component, and restrict console access to trusted networks until patched.

CVE-2020-8468 is a content validation escape (CWE-74, an injection-class flaw) in the client agents of Trend Micro Apex One (2019), OfficeScan XG and Worry-Free Business Security 9.0/9.5/10.0. The attack is network-based but requires the attacker to already hold valid user credentials (CVSS PR:L); once authenticated, they can send crafted content that escapes validation and manipulates certain agent client components on the endpoint. Because the manipulable components are the endpoint security agent itself, impact is rated high for confidentiality, integrity and availability (CVSS 3.1 score 8.8), giving an authenticated attacker a way to tamper with or abuse the protection software on the host. Any organization running these on-premises Trend Micro endpoint agents is affected. The flaw is on CISA's Known Exploited Vulnerabilities catalog (added 2021-11-03) with active exploitation reported in the wild (contemporaneous coverage described attackers attempting to exploit two Apex One zero-days), though a ransomware link is unknown, no public PoC is catalogued, and EPSS estimates a 5.8% probability of exploitation in the next 30 days (93rd percentile).

Do: Apply the Trend Micro-supplied fixes to all Apex One (2019), OfficeScan XG and Worry-Free Business Security 9.0/9.5/10.0 agents per the vendor advisory, as required by the CISA KEV listing. Because exploitation requires valid credentials, review authentication logs for compromised accounts and hunt for signs of unauthorized manipulation of agent components on any unpatched endpoints. Treat unpatched agents as exposed to active attacks; the possible use in ransomware campaigns is currently unknown.

CVE-2021-36741 is an improper input validation flaw (CWE-434) in the management consoles of Trend Micro Apex One, Apex One as a Service, OfficeScan XG, and Worry-Free Business Security 10.0 SP1 that permits the upload of arbitrary files on affected installations. It is triggered remotely over the network (CVSS AV:N) by an attacker who has first obtained logon access to the product's management console (PR:L), with no user interaction required. Successful exploitation lets the attacker place arbitrary files on the management server, with high potential impact to confidentiality, integrity, and availability (CVSS 3.1 score 8.8). Organizations running any of these Trend Micro endpoint-security consoles are affected, including tenants of the cloud-hosted Apex One as a Service. The flaw is in CISA's Known Exploited Vulnerabilities catalog (added 2021-11-03), indicating known in-the-wild exploitation; no public proof-of-concept is known, ransomware use is unconfirmed, and news reports indicate attackers attempted to exploit zero-days in the Trend Micro Apex One platform.

Do: Apply Trend Micro's patches to on-premises Apex One, OfficeScan XG, and Worry-Free Business Security 10.0 SP1 per the vendor advisories and CISA's required action, and confirm the Apex One as a Service-hosted console has been updated by Trend Micro. Because exploitation requires an authenticated console session, restrict management-console logon to trusted administrators, use strong credentials/MFA, and audit console logs for unexpected file uploads or unfamiliar sessions. Treat any internet-exposed management console as higher risk and prioritize patching it.