Cisco Zero-Day Exploited to Implant Malicious Lua Backdoor on Thousands of Devices
Vulnerabilities mentionedAll →
| CVE | Vulnerability | CVSS | EPSS | Flags | Affected | Exposure | Published |
|---|---|---|---|---|---|---|---|
| CVE-2021-1435 | A vulnerability in the web UI of Cisco IOS XE Software could allow an authenticated, remote attacker to inject arbitrary commands that can be executed as the ro A vulnerability in the web UI of Cisco IOS XE Software could allow an authenticated, remote attacker to inject arbitrary commands that can be executed as the root user. This vulnerability is due to insufficient input validation. An attacker could exploit this vulnerability by sending a crafted request to the web UI of an affected device with arbitrary commands injected into a portion of the request. A successful exploit could allow the attacker to execute arbitrary commands as the root user. NVD description · AI analysis pending | 7.2 | 8% |
| — | ||
| 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 | |
| CVE-2023-20273 | Authenticated Command Injection (Root) in Cisco IOS XE Web UI CVE-2023-20273 is an OS command injection flaw (CWE-78) in the web UI feature of Cisco IOS XE Software, caused by insufficient input validation. An authenticated, remote attacker triggers it by sending crafted input to the web UI, and a successful exploit injects commands that run on the underlying operating system with root privileges, yielding full device compromise (in the October 2023 mass-exploitation campaign it was typically chained with the unauthenticated CVE-2023-20198 to obtain initial access and install a persistent implant). Any Cisco IOS XE device with the web UI enabled and reachable from the internet or an untrusted network is affected; this data does not specify the affected release ranges, which are enumerated in Cisco's advisory. Exploitation is confirmed in the wild: CISA added the flaw to the KEV on 2023-10-23 with BOD 23-02 response actions, EPSS is ~90% (100th percentile), and IOS XE edge devices remain recurring targets of Chinese-nexus espionage campaigns (e.g., Salt Typhoon activity against telecoms). Do: Upgrade affected devices to a fixed IOS XE release per Cisco's advisory; as an interim mitigation, disable the HTTP/HTTPS server (ip http server / ip https server) or restrict Web UI access to trusted hosts only. Per BOD 23-02, hunt for compromise on any exposed device — check for unexpected level-15 local accounts and the implant.lua backdoor in flash memory — and immediately report positive findings to CISA. | 7.2 | 90% | KEV |
| mass≈100,000+ internet-exposed IOS XE devices (public scans observed ~40,000+ compromised within days of disclosure) |
Full article461 words · extracted from thehackernews.com · click to collapse
Ravie LakshmananOct 21, 2023Zero-Day / Vulnerability
Cisco has warned of a new zero-day flaw in IOS XE that has been actively exploited by an unknown threat actor to deploy a malicious Lua-based implant on susceptible devices.
Tracked as CVE-2023-20273 (CVSS score: 7.2), the issue relates to a privilege escalation flaw in the web UI feature and is said to have been used alongside CVE-2023-20198 (CVSS score: 10.0) as part of an exploit chain.
"The attacker first exploited CVE-2023-20198 to gain initial access and issued a privilege 15 command to create a local user and password combination," Cisco said in an updated advisory published Friday. "This allowed the user to log in with normal user access."
"The attacker then exploited another component of the web UI feature, leveraging the new local user to elevate privilege to root and write the implant to the file system," a shortcoming that has been assigned the identifier CVE-2023-20273.
A Cisco spokesperson told The Hacker News that a fix that covers both vulnerabilities has been identified and will be made available to customers starting October 22, 2023. In the interim, it's recommended to disable the HTTP server feature.
While Cisco had previously mentioned that a now-patched security flaw in the same software (CVE-2021-1435) had been exploited to install the backdoor, the company assessed the vulnerability to be no longer associated with the activity in light of the discovery of the new zero-day.
"An unauthenticated remote actor could exploit these vulnerabilities to take control of an affected system," the U.S. Cybersecurity and Infrastructure Security Agency (CISA) said. "Specifically, these vulnerabilities allow the actor to create a privileged account that provides complete control over the device."
Successful exploitation of the bugs could allow attackers to gain unfettered remote access to routers and switches, monitor network traffic, inject and redirect network traffic, and use it as a persistent beachhead to the network due to the lack of protection solutions for these devices.
The development comes as more 41,000 Cisco devices running the vulnerable IOS XE software are estimated to have been compromised by threat actors using the two security flaws, per data from Censys and LeakIX.
"On October 19, the number of compromised Cisco devices has ebbed to 36,541," the attack surface management firm said. "The primary targets of this vulnerability are not large corporations but smaller entities and individuals."
Update:
Cisco has officially released software updates to address the two actively exploited security flaws for Cisco IOS XE software release train 17.9, with fixes for versions 17.6, 17.3, and 16.12 in the works. Additional release information can be accessed here.
Found this article interesting? Follow us on Google News, Twitter and LinkedIn to read more exclusive content we post.
Text extracted automatically; images, tables and formatting may be missing. Original: https://thehackernews.com/2023/10/cisco-zero-day-exploited-to-implant.html