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n.runs-SA-2003.001 Cyrus IMSP - Buffer overflow in address book handling
n.runs GmbH
http://www.nruns.com
n.runs-SA-2003.001
security(at)nruns.com
28-Oct-2003
* * *
Vendor: Andrew Systems Group, Carnegie Mellon University
Product: Cyrus IMSP
Vulnerability: Buffer overflow in address book handling
Risk: HIGH
Vendor communication:
Overview:
Cyrus IMSP is a implementation of the IMSP protocol [2].
"The Internet Message Support Protocol (IMSP) is designed to support
the provision of mail in a medium to large scale operation. It is
intended to be used as a companion to the IMAP4 protocol [IMAP4],
providing services which are either outside the scope of mail access
or which pertain to environments which must run more than one IMAP4
server in the same mail domain. The services that IMSP provides are
extended mailbox management, configuration options, and address
books."
There is a remotely exploitable buffer overflow in the Cyrus IMSPd.
The vulnerability can be triggered before authentication. The IMSP
daemon is required to run as root.
Description:
In the function abook_dbname, a sprintf() call takes place. The
function takes two char pointers (dbname and name), which are later
used in the sprintf() call:
sprintf(dbname, abookdb, ownerlen, name, name);
abookdb is defined as
static char abookdb[] = "user/%.*s/abook.%s";
Several functions in the code use abook_dbname() and supply a local
char buffer of 256 bytes as first argument to the function. Since the
second argument "name" is controlled by the user in serveral protocol
messages [2], a remotely exploitable buffer overflow is created.
Example:
nruns@testbox:~$ ./CyRootIMSP.pl localhost 406
[...]
Found suitable return address 0xBFFF95D3
+++ Exploitation successful: uid=0(root) gid=0(root)
groups=0(root),1(bin),2(daemon),3(sys),4(adm),6(disk),10(wheel)
Solution:
The updated software versions are available from
http://cyrusimap.web.cmu.edu.
Credit:
Bug found by Felix Lindner and Michael Guenther of n.runs GmbH.
Additional credits to Steffen Weinreich for support during research.
Greets to Halvar, Johnny Cyberpunk, all@EEye
References:
[1] http://asg.web.cmu.edu/cyrus/download/
[2] http://asg.web.cmu.edu/cyrus/rfc/imsp.html
Unaltered electronic reproduction of this advisory is permitted.
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All warranties are excluded. In no event shall n.runs be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages, even if n.runs has been advised of the possibility of such damages.
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