Re: [Full-disclosure] Possible DOS issue in OpenSSH ssh client

Espen Grøndahl wrote:
During some testing I found a possible bug/issue with OpenSSH ssh client.

MachineA # cat < /dev/zero | nc –l –p 3000

MachineB# ssh someone@MachineA –p 3000

I have tested on OpenBSD 3.9, CentOS 4.3, Debian 3.1 and Solaris 9.

This consumes 50-100% of available CPU time on MachineB ( depending on the
bandwith between them ).

What did the ssh client do? Did it eventually time out (as you would expect)? Or did it hang and never disconnect?

--
Paul Schmehl (pauls@xxxxxxxxxxxx)
Adjunct Information Security Officer
The University of Texas at Dallas
http://www.utdallas.edu/ir/security/

Attachment: smime.p7s
Description: S/MIME Cryptographic Signature

_______________________________________________
Full-Disclosure - We believe in it.
Charter: http://lists.grok.org.uk/full-disclosure-charter.html
Hosted and sponsored by Secunia - http://secunia.com/

Relevant Pages

  • [Full-disclosure] Possible DOS issue in OpenSSH ssh client
    ... During some testing I found a possible bug/issue with OpenSSH ssh client. ... This consumes 50-100% of available CPU time on MachineB (depending on the ...
    (Full-Disclosure)
  • Re: cant open display
    ... Dennis Gilmore wrote: ... >>Up until unpgrading to FC3 I would ssh from machinea on machineb and then ... >>run programs on machineb remotely from machinea. ... > Reading the release notes would help the way ssh works has changed. ...
    (Fedora)
  • thread priority
    ... processes running in the background with equal thread priority. ... Each was getting approximately 50 percent of the CPU time, ... of the two background number-crunching processes got essentially ... Exited SSH, went back to 50/50. ...
    (comp.os.os2.bugs)
  • Re: consecutive rsync between three machines
    ... why do you suggest the option ssh -c and what is the ... (accessable through machineB). ... why not use the ssh option -c, instead of trying to do the echo pipe. ...
    (comp.os.linux.misc)
  • Re: consecutive rsync between three machines
    ... Because I misremembered the command. ... ssh B mkdir /tmp/rsync ... (accessable through machineB). ... why not use the ssh option -c, instead of trying to do the echo pipe. ...
    (comp.os.linux.misc)