CVE-2018-7300

published 2018-02-22

CVE-2018-7300: Directory Traversal / Arbitrary File Write / Remote Code Execution in the User.setLanguage method in eQ-3 AG Homematic CCU2 2.29.2 and earlier allows remote…

Priority P2 78 critical 9.8 CVSS 3.1

AV N AC L PR N UI N S U C H I H A H

EXPLOIT

Directory Traversal / Arbitrary File Write / Remote Code Execution in the User.setLanguage method in eQ-3 AG Homematic CCU2 2.29.2 and earlier allows remote attackers to write arbitrary files to the device's filesystem. This vulnerability can be exploited by unauthenticated attackers with access to the web interface.

Affected

1 ranges

Vendor	Product	Version range	Fixed in
eq-3	homematic_ccu2_firmware	<= 2.29.22	—

Detection & IOCs extracted from sources · hover to see the quote

url /api/homematic.cgi↗

command User.setLanguage↗

command ../../../../../../../..<path>\u0000↗

• → Detect POST requests to /api/homematic.cgi with a JSON body containing the method 'User.setLanguage' and a userName parameter containing directory traversal sequences (e.g., '../../') and/or a null byte (\u0000). ↗
• → Flag unauthenticated JSON-RPC requests (version 1.1) to the homematic.cgi endpoint — the exploit requires no authentication credentials. ↗
• → Inspect Content-Type header for 'application/json' on POST requests to /api/homematic.cgi as the exploit explicitly sets this header. ↗
• → Alert on writes to sensitive paths such as /etc/shadow via the CCU2 web interface, as the exploit demonstrates overwriting that file with attacker-controlled content. ↗

• · The exploit disables TLS certificate verification, so the attack works over both HTTP and HTTPS regardless of certificate validity. Detection rules must cover both schemes on the CCU2 web interface port. ↗
• · The null-byte terminator (\u0000) appended to the userName path is essential to the traversal payload; detection signatures should account for null-byte injection within JSON string values. ↗

CVSS provenance

nvd v3.1 9.8 CRITICAL CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

nvd v2.0 10.0 CRITICAL AV:N/AC:L/Au:N/C:C/I:C/A:C

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CWE-22