BadCandy Webshell threatens unpatched Cisco IOS XE devices, warns Australian government
Vulnerabilities mentionedAll →
| CVE | Vulnerability | CVSS | EPSS | Flags | Affected | Exposure | Published |
|---|---|---|---|---|---|---|---|
| CVE-2023-20198 | Unauthenticated Privilege Escalation in Cisco IOS XE Web UI (Actively Exploited) CVE-2023-20198 is a critical (CVSS 10.0) unauthenticated privilege escalation flaw in the web UI of Cisco IOS XE software, triggered by sending crafted network requests to the exposed web management interface. An attacker with no credentials can use the flaw to gain initial access and issue a privilege 15 command, creating a local user with normal login access; the attacker then chained CVE-2023-20273 (CVSS 7.2) to elevate that account to root and write an implant to the file system. Successful exploitation yields full administrative control of the device, including persistence via the planted implant, on Cisco IOS XE devices with the web UI enabled and reachable from the internet or untrusted networks, including Rockwell Automation Allen-Bradley Stratix 5200 and 5800 switches running IOS XE. Exploitation is confirmed in the wild: the flaw was added to CISA's KEV on 2023-10-16 with a BOD 23-02 directive, EPSS stands at 99.6% (100th percentile), and ongoing campaigns (including the 'BADCANDY' activity flagged by Australia's ASD and Cisco-related telecom intrusions attributed to Salt Typhoon) have been reported. Do: Upgrade affected devices to the fixed releases listed in Cisco's advisory (use Cisco's Software Checker) and, as immediate mitigation, disable the web UI or restrict it to trusted networks/addresses only. Check for compromise by looking for unexpected local user accounts and the implant artifacts Cisco identified (unexpected cisco_tac_alarm.log and cisco_tac.log files in /tmp or /usr/binos/conf), and immediately report positive findings to CISA per BOD 23-02. Keep in mind that patching alone does not remove a root implant, so devices with evidence of compromise should be reimaged or otherwise cleaned per vendor instructions. | 10.0 | 100% | KEV |
| large≈40,000–50,000 internet-exposed IOS XE devices at the time of disclosure (public scan data), within an IOS XE install base in the millions |
Full article367 words · extracted from securityaffairs.com · click to collapse
Pierluigi Paganini
November 01, 2025
Australia warns of attacks on unpatched Cisco IOS XE devices exploiting CVE-2023-20198, allowing BadCandy webshell install.
The Australian Signals Directorate (ASD) warns of ongoing attacks on unpatched Cisco IOS XE devices exploiting CVE-2023-20198, allowing BadCandy webshell infections and admin takeover.
“Cyber actors are installing an implant dubbed ‘BADCANDY’ on Cisco IOS XE devices that are vulnerable to CVE-2023-20198. Variations of the BADCANDY implant have been observed since October 2023, with renewed activity notable throughout 2024 and 2025.” reads the alert issued by the ASD.
An attacker can exploit the vulnerability CVE-2023-20198 (CVSS score 10) in its IOS XE Software to gain administrator privileges and take over vulnerable routers. The advisory published by the vendor states that the exploitation of the vulnerability allows a remote, unauthenticated attacker to create an account on an affected system with privilege level 15 access.
The flaw affects physical and virtual devices running with the Web User Interface (Web UI) feature enabled and that have the HTTP or HTTPS Server feature in use.
Since July 2025, the Australian agency observed over 400 devices potentially compromised with BADCANDY in the country. As of late October 2025, over 150 devices compromised with BADCANDY in Australia are still exposed online.
BADCANDY is a Lua-based webshell exploiting CVE-2023-20198 on Cisco IOS XE devices. It’s non-persistent after reboot, but attackers may retain access via stolen credentials. Patching and restricting web UI access are required to prevent re-exploitation.
“ASD believes actors are able to detect when the BADCANDY implant is removed and are re-exploiting the devices. This further highlights the need to patch against CVE-2023-20198 to avoid re-exploitation.” continues the alert.
ASD is notifying affected entities, providing patching, reboot, hardening, and incident response guidance. The agency will continue alerts to ensure operators know their devices were compromised.
Government experts recommend operators to remove BADCANDY by reviewing and deleting unauthorized privileged accounts, checking unknown tunnel interfaces, and monitoring configuration changes via TACACS+ logging.
Organizations should follow Cisco guidance: disable the HTTP server feature and apply the IOS XE hardening guide to prevent future BADCANDY compromises.
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(SecurityAffairs – hacking, Cisco IOS XE)
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