Thousands of D-Link and QNAP NAS routers compromised by fast-moving AryStinger malware that turns unsecured devices into a malicious proxy botnet

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• QiAnXin XLab uncovered “AryStinger,” malware exploiting old D-Link/Linksys router flaws (CVE‑2013‑3307, CVE‑2016‑5681) to build a proxy/reconnaissance network
• So far 4,300 routers infected, mostly in South Korea (48%) and China (32%), with QNAP NAS devices also targeted via CVE‑2025‑11837
• Compromised devices enable scanning, tunneling, and covert control; researchers advise monitoring logs, binaries in /tmp/bin, and suspicious processes like syswapd0h or syswapd0w

Cybersecurity researchers QiAnXin XLab are warning about an ongoing campaign to create a distributed reconnaissance and proxy network out of people’s routers and NAS devices.

The campaign targets outdated and unsupported routers (mostly D-Link and Linksys), powered by Realtek’s RTL819X chips which were a popular choice between 2012 and 2015. The attackers are leveraging two (ancient) vulnerabilities, CVE-2013-3307 in Linksys models and CVE-2016-5681 in D-Link ones, to infect the devices with a previously undetected piece of malware called AryStinger.

According to the researchers, AryStinger is used during the reconnaissance and planning stages of a more serious cyberattack. Devices infected with this malware can scan the internet, fingerprint services, enumerate subdomains, tunnel traffic, and run commands on demand, all while hiding the location (and true identity) of the attackers.

Targeting NAS devices

“Once compromised by malware like AryStinger that possesses reconnaissance and covert control capabilities, it is equivalent to a hacker placing a permanent "invisible listening device" and "attack springboard" within your network,” the researchers said.

QiAnXin’s XLab says that So far, AryStinger infected 4,300 routers, but stresses that this is not the final number and with the campaign ongoing, will rise even more.

The majority of the victims are located in South Korea (48%) and China (32%), with notable mentions being Sweden, Malaysia, and Singapore.

AryStinger also targets QNAP’s NAS devices, leveraging a code injection flaw in the device’s Malware Remover. This flaw, tracked as CVE-2025-11837, was first discovered during last year’s Pwn2Own event, and was patched in November 2025. The researchers don’t know how many of these devices are currently infected, and say the 4,300 figure only relates to routers.

The researchers did not attribute this attack to any particular threat actor.

To defend against AryStinger, the researchers recommend monitoring the logs for any outbound connections to the C2 and download domains (found here), checking /tmp/bin for unrecognized binaries, and looking for processes named syswapd0h or syswapd0w.

Via The Hacker News