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CVE-2023-41896
CVE ID
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CVE-2023-41896
MITRE ATT&CK
Collection
Command and Control
Credential Access
Defense Evasion
Discovery
Execution
Exfiltration
Impact
Initial Access
Lateral Movement
Persistence
Privilege Escalation
Topic Tags
Description
Home assistant is an open source home automation. Whilst auditing the frontend code to identify hidden parameters, Cure53 detected auth_callback=1, which is leveraged by the WebSocket authentication logic in tandem with the state parameter. The state parameter contains the hassUrl, which is subsequently utilized to establish a WebSocket connection. This behavior permits an attacker to create a malicious Home Assistant link with a modified state parameter that forces the frontend to connect to an alternative WebSocket backend. Henceforth, the attacker can spoof any WebSocket responses and trigger cross site scripting (XSS). Since the XSS is executed on the actual Home Assistant frontend domain, it can connect to the real Home Assistant backend, which essentially represents a comprehensive takeover scenario. Permitting the site to be iframed by other origins, as discussed in GHSA-935v-rmg9-44mw, renders this exploit substantially covert since a malicious website can obfuscate the compromise strategy in the background. However, even without this, the attacker can still send the auth_callback link directly to the victim user. To mitigate this issue, Cure53 advises modifying the WebSocket code’s authentication flow. An optimal implementation in this regard would not trust the hassUrl passed in by a GET parameter. Cure53 must stipulate the significant time required of the Cure53 consultants to identify an XSS vector, despite holding full control over the WebSocket responses. In many areas, data from the WebSocket was properly sanitized, which hinders post-exploitation. The audit team eventually detected the js_url for custom panels, though generally, the frontend exhibited reasonable security hardening. This issue has been addressed in Home Assistant Core version 2023.8.0 and in the npm package home-assistant-js-websocket in version 8.2.0. Users are advised to upgrade. There are no known workarounds for this vulnerability.
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CVSS V3 Severity and Metrics
General Information
Vendors
- home-assistant
Products
- home-assistant,
- home-assistant-js-websocket
References
Additional Info
Technical Analysis
Report as Emergent Threat Response
Report as Exploited in the Wild
CVE ID
AttackerKB requires a CVE ID in order to pull vulnerability data and references from the CVE list and the National Vulnerability Database. If available, please supply below:
