[FD] Grandstream VoIP phone: SSH key backdoor and multiple vulnerabilities leading to RCE as root

The Grandstream GXV3275 is an Android-based VoIP phone. Several vulnerabilities were found affecting this device. * The device ships with a default root SSH key, which could be used as a backdoor: /system/root/.ssh # cat authorized_keys Public key portion is: ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAAAgwCIcYbgmdHTpTeDcBA4IOg5Z7d2By0GXGihZzcTxZC+YTWGUe/HJc+pYDpDrGMWg0hMqd+JPs1GaLNw4pw0Mip6VMT7VjoZ8Z+n2ULNyK1IoTU4C3Ea4vcYVR8804Pvh9vXxC0iuMEr1Jx7SewUwSlABX04uVpEObgnUhpi+hn/H34/ jhzhao@jhzhao-Lenovo Fingerprint: md5 7b:6e:a0:00:19:54:a6:39:84:1f:f9:18:2e:79:61:b5 This issue has not been resolved. * The SSH interface only provides access to a limited CLI. The CLI's ping and traceroute commands will pass user input as parameters to underlying system commands without escaping shell metacharacters. This can be exploited to break out to a shell: GXV3275 > traceroute $(sh) This shell will only see stderr, so we then need to run sh with stdout redirected to stderr: sh 1>&2 This issue has been resolved in firmware version 1.0.3.30. * The web interface exposes an undocumented command execution API: http://DEVICEIP/manager?action=execcmd&command=echo%20%22hello%22%20%3E%20/system/root/test.txt This issue has been resolved in firmware version 1.0.3.30. * The web interface allows unprivileged users to escalate privileges by modifying a cookie on the client side: javascript:void(document.cookie="type=admin") Full details are available here: http://ift.tt/1KL8MLt MITRE was contacted repeatedly requesting CVE names for these issues, but never replied. David

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