There exists an unauthenticated buffer overflow vulnerability
in the POP3 server of Seattle Lab Mail 5.5 when sending a password
with excessive length.
Successful exploitation should not crash either the
service or the server; however, after initial use the
port cannot be reused for successive exploitation until
the service has been restarted. Consider using a command
execution payload following the bind shell to restart
the service if you need to reuse the same port.
The overflow appears to occur in the debugging/error reporting
section of the slmail.exe executable, and there are multiple
offsets that will lead to successful exploitation. This exploit
uses 2606, the offset that creates the smallest overall payload.
The other offset is 4654.
The return address is overwritten with a "jmp esp" call from the
application library SLMFC.DLL found in %SYSTEM%\system32\. This
return address works against all version of Windows and service packs.
The last modification date on the library is dated 06/02/99. Assuming
that the code where the overflow occurs has not changed in some time,
prior version of SLMail may also be vulnerable with this exploit. The
author has not been able to acquire older versions of SLMail for
testing purposes. Please let us know if you were able to get this
exploit working against other SLMail versions.
- stinko <email@example.com>