cbcvebase.
CVE-2016-10176
published 2017-01-30

CVE-2016-10176: The NETGEAR WNR2000v5 router allows an administrator to perform sensitive actions by invoking the apply.cgi URL on the web server of the device. This special…

PriorityP191critical9.8CVSS 3.0
AVNACLPRNUINSUCHIHAH
ITWEXPLOITVulnCheck KEV
Exploited in the wild
EPSS
77.58%
99.5th percentile
The NETGEAR WNR2000v5 router allows an administrator to perform sensitive actions by invoking the apply.cgi URL on the web server of the device. This special URL is handled by the embedded web server (uhttpd) and processed accordingly. The web server also contains another URL, apply_noauth.cgi, that allows an unauthenticated user to perform sensitive actions on the device. This functionality can be exploited to change the router settings (such as the answers to the password-recovery questions) and achieve remote code execution.

Affected

1 ranges
VendorProductVersion rangeFixed in
netgearwnr2000v5_firmware<= 1.0.0.34

Detection & IOCsextracted from sources · hover to see the quote

urlhttp://<target>/BRS_netgear_success.html
urlhttp://<target>/apply_noauth.cgi?/unauth.cgi
urlhttp://<target>/passwordrecovered.cgi
urlhttp://<target>/apply_noauth.cgi?/PWD_password.htm%20timestamp=
urlhttp://<target>/apply_noauth.cgi?/lang_check.html%20timestamp=
urlhttp://<target>/apply_noauth.cgi?/reboot_waiting.htm
path/BRS_netgear_success.html
path/apply_noauth.cgi
path/passwordrecovered.cgi
commandkillall telnetenable; killall utelnetd; /usr/sbin/utelnetd -d -l /bin/sh
otherAMBIT_TELNET_ENABLE+<password>
othersubmit_flag=security_question&answer1=secretanswer1&answer2=secretanswer2&continue=+Continue+
othersubmit_flag=passwd&hidden_enable_recovery=1&Apply=Apply&sysOldPasswd=&sysNewPasswd=&sysConfirmPasswd=&enable_recovery=on&question1=1&answer1=secretanswer1&question2=2&answer2=secretanswer2
  • Detect unauthenticated GET requests to /BRS_netgear_success.html — this endpoint leaks the router serial number used to initiate password recovery exploitation.
  • Detect unauthenticated POST requests to /apply_noauth.cgi with URI parameters referencing /PWD_password.htm or /lang_check.html followed by a numeric timestamp parameter — this is the core exploitation pattern for CVE-2016-10176.
  • Detect GET to /passwordrecovered.cgi without prior authentication — this endpoint returns the admin username and password in cleartext after successful exploitation.
  • Detect rapid sequential POST requests to /apply_noauth.cgi with incrementing or decrementing 8-digit timestamp values — this is the brute-force timestamp pattern used to bypass authentication.
  • Detect UDP packets to port 23 containing the magic string 'AMBIT_TELNET_ENABLE+' — this is the Blowfish-ECB encrypted telnetenable payload used to open a root telnet shell post-exploitation.
  • Detect WWW-Authenticate response headers containing 'WNR2000v5', 'WNR2000v4', or 'WNR2000v3' — the exploit uses this to fingerprint vulnerable targets.
  • Detect POST to /apply_noauth.cgi?/reboot_waiting.htm with body submit_flag=reboot&yes=Yes — attacker-triggered reboot to force fresh timestamp generation.
  • Detect process execution of 'utelnetd -d -l /bin/sh' on the router — this is the payload spawned by the buffer overflow exploit to open an unauthenticated root shell.
  • ·The timestamp brute-force window is configurable: with a forced reboot the exploit searches 5000 seconds back (TIME_OFFSET=5000); without reboot it searches 500000 seconds back. Detection thresholds should account for this wide range of request volume.
  • ·The exploit was confirmed against firmware versions 1.0.0.34 and 1.0.0.18 of the WNR2000v5; hardware revisions v3 and v4 are considered potentially vulnerable but untested.

CVSS provenance

nvdv3.09.8CRITICALCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
nvdv2.07.5HIGHAV:N/AC:L/Au:N/C:P/I:P/A:P
vulncheck9.8CRITICAL
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