cbcvebase.
CVE-2021-46422
published 2022-04-27

CVE-2021-46422: Telesquare SDT-CW3B1 1.1.0 is affected by an OS command injection vulnerability that allows a remote attacker to execute OS commands without any authentication.

PriorityP192critical9.8CVSS 3.1
AVNACLPRNUINSUCHIHAH
ITWEXPLOITVulnCheck KEVInitial access
Exploited in the wild
EPSS
94.75%
99.8th percentile
Telesquare SDT-CW3B1 1.1.0 is affected by an OS command injection vulnerability that allows a remote attacker to execute OS commands without any authentication.

Affected

1 ranges
VendorProductVersion rangeFixed in
telesquaresdt-cs3b1_firmware

Detection & IOCsextracted from sources · hover to see the quote

url/cgi-bin/admin.cgi?Command=sysCommand&Cmd=
path/cgi-bin/admin.cgi
commandCommand=sysCommand&Cmd=id
commandping${IFS}-c${IFS}1${IFS}{{interactsh-url}}
snort
alert http $EXTERNAL_NET any -> $HOME_NET any (msg:"ET EXPLOIT Telesquare SDT-CW3B1 1.1.0 - OS Command Injection (CVE-2021-46422)"; flow:established,to_server; http.method; content:"GET"; http.uri; content:"/cgi-bin/admin.cgi?Command=sysCommand&Cmd="; fast_pattern; startswith; http.header_names; to_lowercase; content:!"|0d 0a|referer|0d 0a|"; reference:cve,2021-46422; reference:url,twitter.com/momika233/status/1528742287072980992; classtype:attempted-admin; sid:2036663; rev:2; metadata:attack_target Networking_Equipment, created_at 2022_05_23, cve CVE_2021_46422, deployment Perimeter, deployment SSLDecrypt, performance_impact Low, confidence Medium, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2024_04_26, reviewed_at 2024_09_12, mitre_tactic_id TA0008, mitre_tactic_name Lateral_Movement, mitre_technique_id T1210, mitre_technique_name Exploitation_Of_Remote_Services;)
  • Exploit requires NO authentication. Any GET request to /cgi-bin/admin.cgi?Command=sysCommand&Cmd= should be treated as suspicious, especially from external/untrusted sources.
  • The Snort/ET rule detects exploitation by matching the URI prefix /cgi-bin/admin.cgi?Command=sysCommand&Cmd= at the start of the HTTP URI, combined with the absence of a Referer header — flag GET requests matching this pattern with no Referer.
  • The exploit parses XML tag <CmdResult> from the CGI response to confirm command execution — defenders can monitor for this tag in HTTP responses from the device.
  • Shodan query 'html:"SDT-CW3B1"' can be used to identify internet-exposed vulnerable devices for asset discovery and attack surface reduction.
  • IFS-substitution evasion technique (${IFS} in place of spaces) is used in the ping-based OOB detection payload — monitor for URL-encoded or literal ${IFS} in HTTP URIs targeting this endpoint.
  • ·The Nuclei template uses an out-of-band (interactsh DNS callback) matcher to confirm exploitation. Detection based solely on HTTP response body may be unreliable as the template matches an empty body word.
  • ·The ET Snort rule (sid:2036663) is classified with 'confidence Medium' — tune accordingly to reduce false positives in environments with legitimate CGI admin access.

CVSS provenance

nvdv3.19.8CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
nvdv2.010.0CRITICALAV:N/AC:L/Au:N/C:C/I:C/A:C
vulncheck9.8CRITICAL
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