Avtech IP Camera / NVR / DVR CSRF / Disclosure / Command Injection
Posted on 12 October 2016
Avtech devices multiple vulnerabilities -------------------------------------------------- Platforms / Firmware confirmed affected: - Every Avtech device (IP camera, NVR, DVR) and firmware version. [4] contains the list of confirmed firmware versions, which are affected. - Product page: http://www.avtech.com.tw/ A'AVTECH, founded in 1996, is one of the worldAs leading CCTV manufacturers. With stably increasing revenue and practical business running philosophy, AVTECH has been ranked as the largest public-listed company among the Taiwan surveillance industry. AVTECH makes every effort on the innovation of technology, product and implementation. Based on years of research and industry experience, AVTECH has obtained a leading position on mobile platform support and provides a full range of surveillance products.AP Avtech is the second most popular search term in Shodan. According to Shodan, more than 130.000 Avtech devices are exposed to the internet. Vulnerabilities --------------- 1) Plaintext storage of administrative password Every user password is stored in clear text. An attacker with access to the device itself can easily obtain the full list of passwords. By exploiting command injection or authentication bypass issues, the clear text admin password can be retrieved. 2) Missing CSRF protection The web interface does not use any CSRF protection. If a valid session exists for the user, the attacker can modify all settings of the device via CSRF. If there is no valid session, but the user did not change the default admin password, the attacker can log in as admin via CSRF as well. 3) Unauthenticated information disclosure Under the /cgi-bin/nobody folder every CGI script can be accessed without authentication. POC: GET /cgi-bin/nobody/Machine.cgi?action=get_capability Example response: Firmware.Version=1011-1005-1008-1002 MACAddress=00:0E:53:xx:xx:xx Product.Type=DVR Product.ID=308B Product.ShortName=V_full_Indep,V_Multistream Video.System=PAL Audio.DownloadFormat=ULAW Video.Input.Num=8 Video.Output.Num=1 Video.Format=H264,MJPEG Video.Format.Default=H264 Video.Resolution=4CIF,CIF Video.Quality=BEST,HIGH,NORMAL,BASIC Video.Local.Input.Num=8 Video.Local.Output.Num=1 Video.Local.Format=H264,MJPEG Audio.Input.Num=8 Audio.Output.Num=1 Audio.Format=ULAW Audio.Local.Input.Num=8 Audio.Local.Output.Num=1 Audio.Local.Format=PCM Language.Default=ENGLISH Language.Support=ENGLISH&CHINESE&JAPANESE&FRANCE&GERMAN&SPANISH&PORTUGUESE&ITALIAN&TURKISH&POLISH&RUSSIAN&CUSTOMIZE&THAI &VIETNAM&DUTCH&GREEK&ARABIC&CZECH&HUNGARIAN&HEBREW&CHINA& Capability=D0,80,A,80 PushNotify.MaxChannel=8 4) Unauthenticated SSRF in DVR devices In case of DVR devices, Search.cgi can be accessed without authentication. This service is responsible for searching and accessing IP cameras in the local network. In newer firmware versions, Search.cgi provides the cgi_query action, which performs an HTTP request with the specified parameters. By modifying the ip, port and queryb64str parameters, an attacker is able to perform arbitrary HTTP requests through the DVR device without authentication. POC: http://<device_ip>/cgi-bin/nobody/Search.cgi?action=cgi_query&ip=google.com&port=80&queryb64str=Lw== 5) Unauthenticated command injection in DVR devices The cgi_query action in Search.cgi performs HTML requests with the wget system command, which uses the received parameters without sanitization or verification. By exploiting this issue, an attacker can execute any system command with root privileges without authentication. POC: http://<device_ip>/cgi-bin/nobody/Search.cgi?action=cgi_query&ip=google.com&port=80&queryb64str=LW==&username=admin%20;XmlAp%20r%20Account.User1.Password>$(ps|grep%20Search.cgi|grep%20-v%20grep|head%20-n%201|awk%20'{print%20"/tmp/"$1".log"}');&password=admin 6) Authentication bypass #1 Video player plugins are stored as .cab files in the web root, which can be accessed and downloaded without authentication. The cab file request verification in the streamd web server is performed with the strstr function, which means that a request should not be authenticated if it contains the A'.cabAP string anywhere in the URL. We note that some of the models contain an additional check in the CgiDaemon, which allows unauthenticated cgi access only under the /cgi-bin/nobody folder. POC: http://<device_ip>/cgi-bin/user/Config.cgi?.cab&action=get&category=Account.* 7) Authentication bypass #2 Cgi scripts in the /cgi-bin/nobody folder can be accessed without authentication (e.g. for login). The streamd web server verifies whether the request can be performed without authentication by searching for the A'/nobodyAP string in the URL with the strstr function. Thus, if a request contains the "/nobody" string anywhere in the URL, it does not have to be authenticated. We note that some of the models contain an additional check in the CgiDaemon, which allows unauthenticated cgi access only under the /cgi-bin/nobody folder. POC: http://<device_ip>/cgi-bin/user/Config.cgi?/nobody&action=get&category=Account.* 8) Unauthenticated file download from web root If a cab file is requested, the web server sends the file without processing it. Because the streamd web server verifies the cab file request by searching for the A'.cabAP string in the URL with the strstr function, any file (even the cgi scripts) in the web root can be downloaded without authentication. POC: http://<device_ip>/cgi-bin/cgibox?.cab 9) Login captcha bypass #1 To prevent brute-forcing attempts, Avtech devices require a captcha for login requests. However, if the login requests contain the login=quick parameter, the captcha verification is bypassed. POC: http://<device_ip>/cgi-bin/nobody/VerifyCode.cgi?account=<b64(username:password)>&login=quick 10) Login captcha bypass #2 Instead of using a random session ID, Avtech devices use the base64-encoded username and password as the Cookie value. Since the IP address of the logged in user is not stored, if an attacker sets the Cookie manually, the captcha verification can by bypassed easily. 11) Authenticated command injection in CloudSetup.cgi Devices that support the Avtech cloud contain CloudSetup.cgi, which can be accessed after authentication. The exefile parameter of a CloudSetup.cgi request specifies the system command to be executed. Since there is no verification or white list-based checking of the exefile parameter, an attacker can execute arbitrary system commands with root privileges. POC: http://<device_ip>/cgi-bin/supervisor/CloudSetup.cgi?exefile=ps 12) Authenticated command injection in adcommand.cgi Some of the Avtech devices contain adcommand.cgi to perform ActionD commands. The adcommand.cgi can be accessed after authentication. In newer devices the ActionD daemon provides the DoShellCmd function, which performs a system call with the specified parameters. Since there is no verification or white list-based checking of the parameter of the DoShellCmd function, an attacker can execute arbitrary system commands with root privileges. POC: POST /cgi-bin/supervisor/adcommand.cgi HTTP/1.1 Host: <device_ip> Content-Length: 23 Cookie: SSID=YWRtaW46YWRtaW4= DoShellCmd "strCmd=ps&" 13) Authenticated command injection in PwdGrp.cgi The PwdGrp.cgi uses the username, password and group parameters in a new user creation or modification request in a system command without validation or sanitization. Thus and attacker can execute arbitrary system commands with root privileges. We are aware that this vulnerability is being exploited in the wild! POC: http://<device_ip>/cgi-bin/supervisor/PwdGrp.cgi?action=add&user=test&pwd=;reboot;&grp=SUPERVISOR&lifetime=5%20MIN 14) HTTPS used without certificate verification The SyncCloudAccount.sh, QueryFromClient.sh and SyncPermit.sh scripts use wget to access HTTPS sites, such as https://payment.eagleeyes.tw, by specifying the no-check-certificate parameter. Thus wget skips server certificate verification and a MITM attack is possible against the HTTPS communication. Timeline 2015.10.19: First attempt to contact with Avtech, but we did not receive any response 2016.05.24: Second attempt to contact Avtech without any response 2016.05.27: Third attempt to contact Avtech by sending e-mail to public Avtech e-mail addresses. We did not receive any response. 2016.xx.xx: Full disclosure POC --- POC script is available to demonstrate the following problems [3]: - Unauthenticated information leakage (capabilities) - Authentication bypass (.cab, nobody) - Unauthenticated SSRF on DVR devices - Unauthenticated command injection on DVR devices - Login captcha bypass with login=quick or manual cookie creation - CloudSetup.cgi command injection after authentication - adcommand.cgi command injection after authentication A video demonstration is also available [1], which presents some of the above problems. Recommendations --------------- Unfortunately there is no solution available for these vulnerabilities at the moment. You can take the following steps to protect your device: - Change the default admin password - Never expose the web interface of any Avtech device to the internet We note that the above vulnerabilities were found within a short period of time without a systematic approach. Based on the vulnerability types we found and the overall code quality, the devices should contain much more problems. Credits ------- This vulnerability was discovered and researched by Gergely Eberhardt (@ebux25) from SEARCH-LAB Ltd. (www.search-lab.hu) References ---------- [1] https://www.search-lab.hu/advisories/126-avtech-devices-multiple-vulnerabilities <http://www.search-lab.hu/advisories/126-avtech-devices-multiple-vulnerabilities> [2] https://youtu.be/BUx8nLlIMxI [3] https://github.com/ebux/AVTECH [4] http://www.search-lab.hu/media/vulnerability_matrix.txt
