CVE-2020-9054

Multiple ZyXEL network-attached storage (NAS) devices running firmware version 5.21 contain a pre-authentication command injection vulnerability, which may allow a remote, unauthenticated attacker to execute arbitrary code on a vulnerable device. ZyXEL NAS devices achieve authentication by using the weblogin.cgi CGI executable. This program fails to properly sanitize the username parameter that is passed to it. If the username parameter contains certain characters, it can allow command injection with the privileges of the web server that runs on the ZyXEL device. Although the web server does not run as the root user, ZyXEL devices include a setuid utility that can be leveraged to run any command with root privileges. As such, it should be assumed that exploitation of this vulnerability can lead to remote code execution with root privileges. By sending a specially-crafted HTTP POST or GET request to a vulnerable ZyXEL device, a remote, unauthenticated attacker may be able to execute arbitrary code on the device. This may happen by directly connecting to a device if it is directly exposed to an attacker. However, there are ways to trigger such crafted requests even if an attacker does not have direct connectivity to a vulnerable devices. For example, simply visiting a website can result in the compromise of any ZyXEL device that is reachable from the client system. Affected products include: NAS326 before firmware V5.21(AAZF.7)C0 NAS520 before firmware V5.21(AASZ.3)C0 NAS540 before firmware V5.21(AATB.4)C0 NAS542 before firmware V5.21(ABAG.4)C0 ZyXEL has made firmware updates available for NAS326, NAS520, NAS540, and NAS542 devices. Affected models that are end-of-support: NSA210, NSA220, NSA220+, NSA221, NSA310, NSA310S, NSA320, NSA320S, NSA325 and NSA325v2

• zyxel nas326 firmware (< 5.21\(aazf.10\)c0) • zyxel nas520 firmware (< 5.21\(aasz.3\)c0) • zyxel nas540 firmware (< 5.21\(aatb.7\)c0) • zyxel nas542 firmware (< 5.21\(abag.7\)c0) • zyxel atp100 firmware (>= 4.35 < 4.35\(abps.3\)c0) • zyxel atp200 firmware (>= 4.35 < 4.35\(abfw.3\)c0) • zyxel atp500 firmware (>= 4.35 < 4.35\(abfu.3\)c0) • zyxel atp800 firmware (>= 4.35 < 4.35\(abiq.3\)c0) • zyxel usg20-vpn firmware (>= 4.35 < 4.35\(abaq.3\)c0) • zyxel usg20w-vpn firmware (>= 4.35 < 4.35\(abar.3\)c0) • zyxel usg40 firmware (>= 4.35 < 4.35\(aala.3\)c0) • zyxel usg40w firmware (>= 4.35 < 4.35\(aalb.3\)c0) • zyxel usg60 firmware (>= 4.35 < 4.35\(aaky.3\)c0) • zyxel usg60w firmware (>= 4.35 < 4.35\(aakz.3\)c0) • zyxel usg110 firmware (>= 4.35 < 4.35\(aaph.3\)c0) • zyxel usg210 firmware (>= 4.35 < 4.35\(aapi.3\)c0) • zyxel usg310 firmware (>= 4.35 < 4.35\(aapj.3\)c0) • zyxel usg1100 firmware (>= 4.35 < 4.35\(aapk.3\)c0) • zyxel usg1900 firmware (>= 4.35 < 4.35\(aapl.3\)c0) • zyxel usg2200 firmware (>= 4.35 < 4.35\(abae.3\)c0) • zyxel vpn50 firmware (>= 4.35 < 4.35\(abhl.3\)c0) • zyxel vpn100 firmware (>= 4.35 < 4.35\(abfv.3\)c0) • zyxel vpn300 firmware (>= 4.35 < 4.35\(abfc.3\)c0) • zyxel vpn1000 firmware (>= 4.35 < 4.35\(abip.3\)c0) • zyxel zywall110 firmware (>= 4.35 < 4.35\(aaaa.3\)c0) • zyxel zywall310 firmware (>= 4.35 < 4.35\(aaab.3\)c0) • zyxel zywall1100 firmware (>= 4.35 < 4.35\(aaac.3\)c0)