Full Disclosure mailing list archives
Re: FYI: Apache httpd NoFollowSymLink follows symlinks feature
From: halfdog <me () halfdog net>
Date: Fri, 24 Jun 2011 16:02:34 +0000
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Christian Sciberras wrote:
I think you meant "apache follows symlinks even when -FollowSymLinks is *not* set". Otherwise it doesn't seem to make sense?
No. Unless I made a mistake while testing AND misunderstood the documentation, even with -FollowSymLinks set, apache will follow symlinks (see POC). You might want to read the last line in section "FollowSymlink" in http://httpd.apache.org/docs/2.2/mod/core.html#options I, for myself, made the same assumption about -FollowSymLink, but the specification states, that the symlink-check is not race-free.
On Fri, Jun 24, 2011 at 5:14 PM, halfdog <me () halfdog net <mailto:me () halfdog net>> wrote: For those, who did not already know: Due to specification, apache follows symlinks even when -FollowSymLinks is set, when the data is modified concurrently. This can be trivially shown as demonstrated in http://www.halfdog.net/Security/2011/ApacheNoFollowSymlinkTimerace/ . When performing host hardening, do not think, the -FollowSymLinks option alone will prevent you from symlink attacks. _______________________________________________ Full-Disclosure - We believe in it. Charter: http://lists.grok.org.uk/full-disclosure-charter.html Hosted and sponsored by Secunia - http://secunia.com/
- -- http://www.halfdog.net/ PGP: 156A AE98 B91F 0114 FE88 2BD8 C459 9386 feed a bee -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (GNU/Linux) iD8DBQFOBLUWxFmThv7tq+4RAtS5AJ9mZN4MxHZSqSDUmbAXZXboj63d6ACfbUrZ 6zO2slfjjl2Motme3y+Affo= =1CyN -----END PGP 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/
Current thread:
- FYI: Apache httpd NoFollowSymLink follows symlinks feature halfdog (Jun 24)
- Re: FYI: Apache httpd NoFollowSymLink follows symlinks feature Christian Sciberras (Jun 24)
- Re: FYI: Apache httpd NoFollowSymLink follows symlinks feature halfdog (Jun 24)
- Re: FYI: Apache httpd NoFollowSymLink follows symlinks feature Ferenc Kovacs (Jun 24)
- Re: FYI: Apache httpd NoFollowSymLink follows symlinks feature Christian Sciberras (Jun 24)
- Re: FYI: Apache httpd NoFollowSymLink follows symlinks feature halfdog (Jun 24)
- Re: FYI: Apache httpd NoFollowSymLink follows symlinks feature Ferenc Kovacs (Jun 24)
- Re: FYI: Apache httpd NoFollowSymLink follows symlinks feature Christian Sciberras (Jun 24)