===================================================================== CERT-Renater Note d'Information No. 2013/VULN28 _____________________________________________________________________ DATE : 05/07/2013 HARDWARE PLATFORM(S): Digital Alert Systems DASDEC EAS devices, Monroe Electronics One-Net E189 EAS devices. OPERATING SYSTEM(S): Monroe Electronics firmware version 2.0-2, Digital Alert Systems firmware version 2.0-2. ====================================================================== http://www.kb.cert.org/vuls/id/662676 ______________________________________________________________________ Vulnerability Note VU#662676 Digital Alert Systems DASDEC and Monroe Electronics R189 One-Net firmware exposes private root SSH key Original Release date: 26 juin 2013 | Last revised: 02 juil. 2013 Overview Digital Alert Systems DASDEC and Monroe Electronics One-Net E189 Emergency Alert System (EAS) devices exposed a shared private root SSH key in publicly available firmware images. An attacker with SSH access to a device could use the key to log in with root privileges. Description The Digital Alert Systems DASDEC-I and DASDEC-II and Monroe Electronics R189 One-Net/R189SE One-NetSE are Linux-based EAS encoder/decoder (ENDEC) devices that are used to broadcast EAS messages over digital and analog channels. IOActive has reported several security issues affecting these devices. The most severe of these issues is the public disclosure of the default private root SSH key. The less severe issues could also contribute to an attacker's ability to compromise a vulnerable device. Compromised root SSH key (CVE-2013-0137) Publicly available firmware images for these devices included a private root SSH key that was authorized to log in to the devices (CWE-798, CWE-321). The fingerprint for the compromised SSH key is 0c:89:49:f7:62:d2:98:f0:27:75:ad:e9:72:2c:68:c3. Although this key is not hard-coded, it may be impractical for less technical users to manually disable or change they key prior to firmware version 2.0-2. Predictable session ID IOActive reports that the administrative web server uses a predictable, monotonically increasing session ID. This finding is based on running the web server in a test environment. Testing on a variety of firmware versions on devices both at the factory and in the field, Monroe Electronics could not reproduce this finding. Log information disclosure Logs available via the web server provide a variety of information about the configuration, operation, and status of the device (CWE-532). Some of the log information is public and may be required by regulation. Predictable password generation The dasdec_mkuser script generates passwords in a deterministic way (CWE-341), however these passwords are not for administrative access, and the script is not used for general user account configuration. Default password Like many similar devices, the DASDEC and One-Net ENDECs use default administrative credentials. Some sites fail to change the default administrative password and allow unrestricted internet access. Impact An attacker with the private key and SSH access can log in to a device with root privileges. Predictable session IDs could allow an attacker to take control of an existing administrative web session. Predictable and unchanged default passwords can allow an attacker to log in to a device with root privileges. Devices exposed to the internet are at particularly high risk, for example, see Secure EAS Codecs Prevent Zombie Attacks and US-CERT Alert TA13-175A. Logs may disclose configuration information that can benefit an attacker. Solution Apply an update On April 24, 2013, Monroe Electronics and Digital Alert Systems released firmware version 2.0-2 that disables the compromised SSH key, provides a simplified user option to install new unique keys, and enforces a new password policy. Monroe Electronics has taken considerable effort to provide update information to DASDEC and One-NetSE users. DASDEC users can obtain updated firmware and release notes by contacting . R189 One-Net users can contact . Disable compromised SSH key The compromised root SSH key should be disabled immediately, especially if the SSH service is exposed to untrusted networks such as the internet. If SSH connectivity is required, generate, install, and test new SSH keys before disabling the compromised key. The fingerprint for the compromised SSH key is 0c:89:49:f7:62:d2:98:f0:27:75:ad:e9:72:2c:68:c3. Manually inspect SSH keys To identify a compromised key, examine the authorized_keys file at /root/.ssh/authorized_keys2.dasdec and use the ssh-keygen command to show SSH key fingerprints. The following example shows the fingerprint for the compromised key: $ ssh-keygen -l -f authorized_keys2.dasdec 1024 0c:89:49:f7:62:d2:98:f0:27:75:ad:e9:72:2c:68:c3 wood@endec1 (DSA) Note that ssh-keygen only shows the fingerprint for the first key/line in the file. If authorized_keys2.dasdec contains multiple keys (multiple lines, one key per line), it will be necessary to extract each key (line) to a separate file and run the ssh-keygen command on each key/file. These shell scripts can be used to list and test multiple SSH keys in an authorized_keys file: http://www.cert.org/downloads/vuls/662676/ssh-key-test.sh https://raw.github.com/aspiers/ssh-config/master/bin/ssh-list-pubkeys To generate new SSH keys, use ssh-kegen. Restrict access If for some reason you are not able to remove and replace the compromised SSH key, restrict access to the SSH service to highly trusted hosts and networks only. As a general good security practice, restrict access to all services to trusted hosts and networks. Change default passwords Change any default passwords, and do not deploy production systems without changing default passwords. Search engines like Shodan can index systems exposed to the internet and default passwords are usually documented and well-known. It is often trivial for an attacker to identify and access systems on the internet using default passwords. Vendor Information (Learn More) Vendor Status Date Notified Date Updated Digital Alert Systems Affected 18 Jan 2013 26 Jun 2013 Monroe Electronics Affected 18 Jan 2013 24 Jun 2013 If you are a vendor and your product is affected, let us know. CVSS Metrics (Learn More) Group Score Vector Base 10,0 AV:N/AC:L/Au:N/C:C/I:C/A:C Temporal 8,7 E:ND/RL:OF/RC:C Environmental 6,8 CDP:LM/TD:M/CR:ND/IR:M/AR:ND References http://www.monroe-electronics.com/EAS_pages/prod_r189se.html http://www.digitalalertsystems.com/products_enc-dec.html http://www.monroe-electronics.com/MONROE_ELECTRONICS_PDF/130604-Monroe-Security-PR.pdf http://www.digitalalertsystems.com/pdf/130604-Monroe-Security-PR.pdf http://www.digitalalertsystems.com/pdf/wpdas-122.pdf http://www.fcc.gov/guides/emergency-alert-system-eas http://www.commlawblog.com/2013/02/articles/broadcast/fcc-urges-broadcasters-to-secure-eas-equipment/ http://www.broadcastlawblog.com/2013/02/articles/emergency-communications/hackers-use-eas-to-send-alert-of-zombie-attack-fcc-issues-urgent-warning-to-broadcasters-to-secure-their-eas-systems/ http://www.radioworld.com/article/eas-hack-cap-not-the-issue-internet-security-is/217746 http://www.radioworld.com/article/stations-urged-to-protect-their-eas/217746 http://transition.fcc.gov/pshs/techtopics/techtopics21.html http://www.thebdr.net/articles/fcc/eas/eas.html http://www.thebdr.net/articles/fcc/eas/EAS-Q5.pdf http://cwe.mitre.org/data/definitions/798.html http://cwe.mitre.org/data/definitions/532.html http://cwe.mitre.org/data/definitions/341.html http://cwe.mitre.org/data/definitions/320.html http://cwe.mitre.org/data/definitions/321.html http://www.us-cert.gov/ncas/alerts/TA13-175A http://www.cert.org/downloads/vuls/662676/ssh-key-test.sh https://raw.github.com/aspiers/ssh-config/master/bin/ssh-list-pubkeys Credit Thanks to Mike Davis and Cesar Cerrudo of IOActive for reporting these issues. Thanks also to Monroe Electronics for their efforts to contact affected users. This document was written by Art Manion. Other Information CVE IDs: CVE-2013-0137 Date Public: 24 juin 2013 Date First Published: 26 juin 2013 Date Last Updated: 02 juil. 2013 Document Revision: 86 Feedback If you have feedback, comments, or additional information about this vulnerability, please send us email. ====================================================================== ========================================================= Serveur de référence du CERT-Renater https://services.renater.fr/ssi/ ========================================================== + CERT-RENATER | tel : 01-53-94-20-44 + + 23 - 25 Rue Daviel | fax : 01-53-94-20-41 + + 75013 Paris | email: cert@support.renater.fr + ==========================================================