CVE-2021-20173

published 2021-12-30

CVE-2021-20173: Netgear Nighthawk R6700 version 1.0.4.120 contains a command injection vulnerability in update functionality of the device. By triggering a system update check…

Priority P2 60 high 8.8 CVSS 3.1

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

Netgear Nighthawk R6700 version 1.0.4.120 contains a command injection vulnerability in update functionality of the device. By triggering a system update check via the SOAP interface, the device is susceptible to command injection via preconfigured values.

Affected

1 ranges

Vendor	Product	Version range	Fixed in
netgear	r6700_firmware	—	—

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

url POST /soap/server_sa/ HTTP/1.0↗

other SOAPAction: urn:NETGEAR-ROUTER:service:DeviceConfig:1#CheckNewFirmware↗

cookie sess_id=018b49310551ca2de378a56e5f03294bc4c58e2b2dd8671d211abfbddaeb932dd8b60666d6c406356e71620c004fa226094ab2888d422f7133bf377490278819; SameSite=Strict↗

ua SOAP Toolkit 3.0↗

command rm -f %s %s %s;wget -b --tries=2 --timeout=5 -o %s --ca-certificate /opt/xagent/certs/%s -O %s↗

path /opt/xagent/certs/↗

process upnpd↗

• → Monitor for HTTP POST requests to /soap/server_sa/ with SOAPAction header containing 'CheckNewFirmware' — this is the trigger endpoint for the command injection vulnerability. ↗
• → Alert on the upnpd process spawning shell commands (system() calls) containing 'wget' or 'rm -f', as these indicate exploitation of the command injection via preconfigured device values. ↗
• → The vulnerability requires prior authentication; look for authenticated SOAP sessions (sess_id cookie) followed immediately by CheckNewFirmware SOAP action as a behavioral chain indicator. ↗
• → Flag traffic with User-Agent 'SOAP Toolkit 3.0' targeting Netgear router SOAP endpoints, as this is the user-agent used in the documented exploit request. ↗

• · The command injection is triggered via preconfigured values already stored on the device — the attacker does not inject directly in the SOAP request body but rather causes the device to use its own stored (potentially attacker-influenced) configuration values in unsanitized system() calls. ↗
• · Three separate instances of unsanitized system() calls exist in the upnpd binary; detection/patching must account for all three code paths, not just the one documented example. ↗
• · Exploitation requires prior authentication to the device before the SOAP CheckNewFirmware request can be issued; unauthenticated access alone is insufficient. ↗

CVSS provenance

nvd v3.1 8.8 HIGH CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

nvd v2.0 6.5 MEDIUM AV:N/AC:L/Au:S/C:P/I:P/A:P

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