Detect CVE-2026-65400 Screen Sharing exploitation via SSFileCopy helpers - #6675
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shashank-elastic wants to merge 11 commits into
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Detect CVE-2026-65400 Screen Sharing exploitation via SSFileCopy helpers#6675shashank-elastic wants to merge 11 commits into
shashank-elastic wants to merge 11 commits into
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Pull request overview
Adds new macOS Elastic Defend detection rules to identify suspected exploitation activity related to CVE-2026-65400 (Screen Sharing), focusing on the Screen Sharing file-copy helper binaries and their related persistence behaviors.
Changes:
- Adds a file-based EQL rule to detect
SSFileCopyReceiverwriting to common macOS persistence locations. - Adds a process-based rule intended to detect anomalous
SSFileCopySenderexecution consistent with pre-auth exploitation attempts.
Reviewed changes
Copilot reviewed 2 out of 2 changed files in this pull request and generated 4 comments.
| File | Description |
|---|---|
| rules/macos/persistence_ssfilecopyreceiver_file_writes.toml | New EQL file-write detection for SSFileCopyReceiver targeting persistence-relevant paths. |
| rules/macos/initial_access_ssfilecopysender_root_execution.toml | New process execution detection for SSFileCopySender intended to flag pre-auth exploitation indicators. |
Suppressed comments (1)
rules/macos/initial_access_ssfilecopysender_root_execution.toml:100
- This rule is set to
type = "query", but the query body is EQL (process where ...). Set the ruletypeto"eql"(and ensurelanguage = "eql") or rewrite the query in KQL.
type = "query"
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| "/Library/LaunchDaemons/*.plist", | ||
| "/Library/LaunchAgents/*.plist", | ||
| "/Users/*/Library/LaunchAgents/*.plist", | ||
| "/private/var/*/Library/LaunchAgents/*.plist" |
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| file.name in ( | ||
| ".zshenv", ".zshrc", ".zprofile", ".zlogin", | ||
| ".bashrc", ".bash_profile", ".bash_login", ".profile", | ||
| "config.fish", "environment.plist" | ||
| ) or |
| id = "T1098.004" | ||
| name = "SSH Authorized Keys" | ||
| reference = "https://attack.mitre.org/techniques/T1098/004/" | ||
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Co-authored-by: Eric Forte <119343520+eric-forte-elastic@users.noreply.github.com>
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shashank-elastic
requested review from
Aegrah,
Samirbous,
bryans3c and
eric-forte-elastic
August 20, 2026 07:29
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Samirbous
reviewed
Aug 24, 2026
Samirbous
reviewed
Aug 24, 2026
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Samirbous
reviewed
Aug 24, 2026
Co-authored-by: Samirbous <64742097+Samirbous@users.noreply.github.com>
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Aegrah
approved these changes
Aug 25, 2026
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| description = """ | ||
| Identifies the macOS Screen Sharing file copy helper SSFileCopyReceiver creating or modifying files in common | ||
| persistence locations such as LaunchDaemons/LaunchAgents, shell profiles, SSH authorized_keys, cron tabs, and hidden paths | ||
| under root's home directory. SSFileCopyReceiver performs file writes with root authority on behalf of a remote viewer. |
Contributor
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Current logic does not filter by location to just the root's home directory. Should this be updated to match?
| OR file.path LIKE "/private/var/at/tabs/*" | ||
| OR file.path LIKE "/var/at/tabs/*" | ||
| OR file.path LIKE "/private/var/root/.*/*" | ||
| OR file.path LIKE "/var/root/.*/*" |
Contributor
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Paths like .*/* only match a hidden directory plus a hidden file. Is this intentional? Current logic would miss something like /var/root/.payload.
| [rule.threat.tactic] | ||
| id = "TA0004" | ||
| name = "Privilege Escalation" | ||
| reference = "https://attack.mitre.org/tactics/TA0004/" No newline at end of file |
Contributor
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Nit. Missing EOF newline.
| [rule.threat.tactic] | ||
| id = "TA0003" | ||
| name = "Persistence" | ||
| reference = "https://attack.mitre.org/tactics/TA0003/" No newline at end of file |
Contributor
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Nit. Missing EOF newline.
| | WHERE host.os.type == "macos" | ||
| AND event.type == "start" | ||
| AND process.name == "SSFileCopySender" | ||
| AND KQL(""" process.args : "0" AND process.args : "80" """) |
Contributor
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Just checking, based off reading through https://www.huntress.com/blog/macos-screen-sharing-rce-patched this can also happen on legacy VNC auth where root is expected and not malicious. Should we note that in the FP guidance?
Samirbous
approved these changes
Aug 27, 2026
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Pull Request
Issue link(s): NA
Summary - What I changed
SSFileCopySenderandSSFileCopyReceiver, which perform privileged file operations during exploitation.How To Test
Process Events
File Events
Checklist
bug,enhancement,schema,maintenance,Rule: New,Rule: Deprecation,Rule: Tuning,Hunt: New, orHunt: Tuningso guidelines can be generatedmeta:rapid-mergelabel if planning to merge within 24 hoursContributor checklist