[UNIX] Dropbear SSH Server svr_ses.childpidsize Buffer Overflow

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Dropbear SSH Server svr_ses.childpidsize Buffer Overflow
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SUMMARY

<http://matt.ucc.asn.au/dropbear/dropbear.html> Dropbear SSH Server is "a
small Secure Shell server suitable for embedded environments. It
implements various features of the SSH 2 protocol, including X11 and
Authentication agent forwarding".

A buffer overflow vulnerability in Dropbear SSH Server allows remote code
execution.

DETAILS

Vulnerable Systems:
* Dropbear SSH Server versions prior to 0.47

Immune Systems:
* Dropbear SSH Server version 0.47 (download
<http://matt.ucc.asn.au/dropbear/dropbear-0.47.tar.bz2> here)

Fix for buffer allocation error in server code, could potentially allow
authenticated users to gain elevated privileges. All multi-user systems
running the server should upgrade or apply the patch.

Fix:
--- svr-chansession.c
+++ svr-chansession.c
@@ -810,7 +810,7 @@
/* need to increase size */
if (i == svr_ses.childpidsize) {
svr_ses.childpids = (struct
ChildPid*)m_realloc(svr_ses.childpids,
- sizeof(struct ChildPid) * svr_ses.childpidsize+1);
+ sizeof(struct ChildPid) * (svr_ses.childpidsize+1));
svr_ses.childpidsize++;
}



ADDITIONAL INFORMATION

The original article can be found at:
<http://matt.ucc.asn.au/dropbear/dropbear.html>
http://matt.ucc.asn.au/dropbear/dropbear.html



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