*RS232-NET Converter (JTC-200) - Multiple vulnerabilities*
About RS232-NET Converter (model JTC-200)
*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
*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
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
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
bin dev etc nfs proc swap usb var
# cd etc
ConfigPage WRConfig.ini config inetd.conf inittab ppp protocols rc
# 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.