CVE-2024-25636
📋 TL;DR
CVE-2024-25636 is a content-type validation vulnerability in Misskey that allows account takeover through ActivityPub protocol exploitation. Attackers can impersonate legitimate users on remote servers by uploading malicious Activity Streams documents. This affects all Misskey instances prior to version 2024.2.0 that interact with vulnerable remote servers.
💻 Affected Systems
- Misskey
📦 What is this software?
Misskey by Misskey
⚠️ Risk & Real-World Impact
Worst Case
Complete account takeover on remote Misskey instances, allowing attackers to impersonate legitimate users, post malicious content, and potentially pivot to other systems.
Likely Case
Targeted account impersonation and takeover on specific vulnerable remote servers that accept arbitrary user uploads.
If Mitigated
Limited impact if remote servers properly validate uploads or if Content-Type validation is implemented.
🎯 Exploit Status
Exploitation requires attacker to register on a vulnerable remote server and upload crafted documents, then trigger Misskey to fetch them.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 2024.2.0
Vendor Advisory: https://github.com/misskey-dev/misskey/security/advisories/GHSA-qqrm-9grj-6v32
Restart Required: Yes
Instructions:
1. Update Misskey to version 2024.2.0 or later. 2. Restart the Misskey service. 3. Verify the patch is applied by checking the version.
🔧 Temporary Workarounds
Content-Type Validation
allImplement server-side validation to ensure remote Activity Streams responses have correct Content-Type header.
Restrict Remote Server Interactions
allLimit which remote servers your Misskey instance can fetch Activity Streams from.
🧯 If You Can't Patch
- Implement network segmentation to isolate Misskey instances from untrusted remote servers.
- Deploy WAF rules to detect and block malicious Activity Streams requests.
🔍 How to Verify
Check if Vulnerable:
Check if Misskey version is below 2024.2.0 and review ActivityPub resolver code for Content-Type validation.Check Version:
Check package.json or run 'npm list misskey' in the installation directory.Verify Fix Applied:
Verify version is 2024.2.0 or later and check that ApResolverService validates Content-Type headers.📡 Detection & Monitoring
Log Indicators:
- Unusual ActivityPub fetch patterns
- Failed Content-Type validation attempts
- Account takeover attempts
Network Indicators:
- Suspicious Activity Streams requests to/from untrusted servers
- Unexpected Content-Type headers in responses
SIEM Query:
source="misskey" AND ("ActivityPub" OR "ApResolver") AND ("fetch" OR "remote")🔗 References
- https://github.com/misskey-dev/misskey/blob/2024.2.0-beta.10/packages/backend/src/core/activitypub/ApResolverService.ts#L69-L119
- https://github.com/misskey-dev/misskey/blob/2024.2.0-beta.10/packages/backend/src/core/activitypub/models/ApNoteService.ts#L112-L308
- https://github.com/misskey-dev/misskey/blob/2024.2.0-beta.10/packages/backend/src/server/api/endpoints/ap/show.ts#L125-L143
- https://github.com/misskey-dev/misskey/commit/9a70ce8f5ea9df00001894809f5ce7bc69b14c8a
- https://github.com/misskey-dev/misskey/security/advisories/GHSA-qqrm-9grj-6v32
- https://github.com/misskey-dev/misskey/blob/2024.2.0-beta.10/packages/backend/src/core/activitypub/ApResolverService.ts#L69-L119
- https://github.com/misskey-dev/misskey/blob/2024.2.0-beta.10/packages/backend/src/core/activitypub/models/ApNoteService.ts#L112-L308
- https://github.com/misskey-dev/misskey/blob/2024.2.0-beta.10/packages/backend/src/server/api/endpoints/ap/show.ts#L125-L143
- https://github.com/misskey-dev/misskey/commit/9a70ce8f5ea9df00001894809f5ce7bc69b14c8a
- https://github.com/misskey-dev/misskey/security/advisories/GHSA-qqrm-9grj-6v32
