Threat Signal Report

Path Traversal Vulnerability in Arcadyan Firmware Putting Millions of IoT Devices at Risk

Description

FortiGuard Labs is aware of a report that a path traversal vulnerability (CVE-2021-20090) in Arcadyan firmware used in routers leads to an authentication bypass. Successfully exploiting the vulnerability allows the attacker to bypass authentication to access restricted pages and perform any action on the device without authentication. According to security vendor Tenable, the vulnerability in Arcadyan's firmware, "has existed for at least 10 years and has therefore found its way through the supply chain into at least 20 models across 17 different vendors." There also is a report that the vulnerability is being exploited in the wild in order to deploy Mirai malware.


When was the Vulnerability Disclosed?

The vulnerability was disclosed by security vendor Tenable on August 3rd, 2021.


How Serious of an Issue is This?

HIGH. According to Tenable, the vulnerability has existed for at least 10 years and has therefore found its way through the supply chain into at least 20 models across 17 different vendors". Also security vendor Juniper reported that the vulnerability is being exploited in the wild in order to deploy Mirai malware.

Many routers do not receive periodic security updates from their manufacturers and when they do they most often need to be applied manually.


What is the Vulnerability Exploited in this Attack in Order to Deliver Mirai malware?

The exploited vulnerability is a path traversal vulnerability (CVE-2021-20090), which allows unauthenticated users to access restricted pages and take control of the affected device. The vulnerability is in Arcadyan's router firmware that is used by various router manufactures.


Which Routers are Affected?

Tenable provided the following list of affected routers. Note that as Tenable stated the vulnerability has existed more than 10 years, there may be other affected routers.

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VendorDeviceFound on version
ADBADSL wireless IAD router1.26S-R-3P
ArcadyanARV751900.96.00.96.617ES
ArcadyanVRV95176.00.17 build04
ArcadyanVGV75193.01.116
ArcadyanVRV95181.01.00 build44
ASMAXBBR-4MG / SMC7908 ADSL0.08
ASUSDSL-AC88U (Arc VRV9517)1.10.05 build502
ASUSDSL-AC87VG (Arc VRV9510)1.05.18 build305
ASUSDSL-AC31001.10.05 build503
ASUSDSL-AC68VG5.00.08 build272
BeelineSmart Box Flash1.00.13_beta4
British TelecomWE410443-SA1.02.12 build02
BuffaloWSR-2533DHPL21.02
BuffaloWSR-2533DHP31.24
BuffaloBBR-4HG
BuffaloBBR-4MG2.08 Release 0002
BuffaloWSR-3200AX4S1.1
BuffaloWSR-1166DHP21.15
BuffaloWXR-5700AX7S1.11
Deutsche TelekomSpeedport Smart 3010137.4.8.001.0
HughesNetHT2000W0.10.10
KPNExperiaBox V10A (Arcadyan VRV9517)5.00.48 build453
KPNVGV75193.01.116
O2HomeBox 64411.01.36
OrangeLiveBox Fibra (PRV3399)00.96.00.96.617ES
SkinnySmart Modem (Arcadyan VRV9517)6.00.16 build01
SparkNZSmart Modem (Arcadyan VRV9517)6.00.17 build04
Telecom (Argentina)Arcadyan VRV9518VAC23-A-OS-AM1.01.00 build44
TelMexPRV33AC1.31.005.0012
TelMexVRV7006
TelstraSmart Modem Gen 2 (LH1000)0.13.01r
TelusWiFi Hub (PRV65B444A-S-TS)v3.00.20
TelusNH20A1.00.10debug build06
VerizonFios G31002.0.0.6
VodafoneEasyBox 9044.16
VodafoneEasyBox 90330.05.714
VodafoneEasyBox 80220.02.226


What is Mirai Malware?

Mirai is a Linux malware that targets IoT devices to form a Mirai botnet which is typically used for large-scale DDoS attacks. Mirai's source code was made available in 2016 by a Hackforums user "Anna-senpai", named after a female character in Japanese novel "Shimoneta: A Boring World Where the Concept of Dirty Jokes Doesn't Exist", which prompted other attackers to develop and release subsequent variants.


FortiGuard Labs recently published a blog on Mirai malware and its variants. Please see a link to "The Ghosts of Mirai" in the Appendix.


Is the Patch Available for CVE-2021-20090?

Unconfirmed as the vulnerability needs to be fixed by each router manufactures.


What is the Status of Coverage?

Customers running the latest IPS definitions are protected by the following signature:


Arcadyan.Routers.images.Path.Authentication.Bypass


FortiGuard Labs provides the following AV coverage for the associated Miral malware, some of which are not directly related to the attack but came from the same IP involved in the CVE-2021-20090 attack:


ELF/Mirai.AE!tr

ELF/Mirai.ASX!tr

ELF/Mirai.BL!tr

ELF/Mirai.BO!tr

ELF/Mirai.GG!tr

ELF/Mirai.IA!tr

ELF/Mirai.VI!tr

ELF/DDoS.CIA!tr

BAT/Agent.1763!tr.dldr

BAT/Agent.4406!tr.dldr

ELF/Gafgyt.LT!tr


All known network IOC's are blocked by the FortiGuard WebFiltering client.


Any Other Suggested Mitigation?

As a mitigation, FortiGuard Labs recommends to disable the remote (WAN-side) administration services on the affected router and disable the web interface on the WAN.

Telemetry


Definitions

Traffic Light Protocol

Color When Should it Be used? How may it be shared?

TLP: RED

Not for disclosure, restricted to participants only.
Sources may use TLP:RED when information cannot be effectively acted upon by additional parties, and could lead to impacts on a party's privacy, reputation, or operations if misused. Recipients may not share TLP:RED information with any parties outside of the specific exchange, meeting, or conversation in which it was originally disclosed. In the context of a meeting, for example, TLP:RED information is limited to those present at the meeting. In most circumstances, TLP:RED should be exchanged verbally or in person.

TLP: AMBER

Limited disclosure, restricted to participants’ organizations.
Sources may use TLP:AMBER when information requires support to be effectively acted upon, yet carries risks to privacy, reputation, or operations if shared outside of the organizations involved. Recipients may only share TLP:AMBER information with members of their own organization, and with clients or customers who need to know the information to protect themselves or prevent further harm. Sources are at liberty to specify additional intended limits of the sharing: these must be adhered to.

TLP: GREEN

Limited disclosure, restricted to the community.
Sources may use TLP:GREEN when information is useful for the awareness of all participating organizations as well as with peers within the broader community or sector. Recipients may share TLP:GREEN information with peers and partner organizations within their sector or community, but not via publicly accessible channels. Information in this category can be circulated widely within a particular community. TLP:GREEN information may not be released outside of the community.

TLP: WHITE

Disclosure is not limited.
Sources may use TLP:WHITE when information carries minimal or no foreseeable risk of misuse, in accordance with applicable rules and procedures for public release. Subject to standard copyright rules, TLP:WHITE information may be distributed without restriction.