Red Hat Bugzilla – Bug 164927
CVE-2005-2475 TOCTOU issue in unzip
Last modified: 2007-11-30 17:07:19 EST
This issue was posted to bugtraq by Imran Ghory
If a malicious local user has write access to a directory in which a
target user is using unzip to extract a file to then a
TOCTOU bug can be exploited to change the permission of any file
belonging to that user.
On decompressing unzip copies the permissions from the compressed
file to the uncompressed file. However there is a gap between the
uncompressed file being written (and it's file handler being close)
and the permissions of the file being changed.
During this gap a malicious user can remove the decompressed file and
replace it with a hard-link to another file belonging to the user.
unzip will then change the permissions on the hard-linked file to be
the same as that of the compressed file.
The vulnerable line of code can be found on line 1160 of the file
unix.c where chmod is used (rather than fchmod). unzip also use's
chmod in a number of other places which may also be vulnerable to
This issue should also affect RHEL2.1 and RHEL3
Patches are in cvs now (rhel4, rhel3, rhel2.1).
This request was evaluated by Red Hat Product Management for inclusion in a Red
Hat Enterprise Linux maintenance release. Product Management has requested
further review of this request by Red Hat Engineering, for potential
inclusion in a Red Hat Enterprise Linux Update release for currently deployed
products. This request is not yet committed for inclusion in an Update
I put this bug to state modified - in the present fix there is a bug which
should be fixed and there is necessary to add bz to changelog.
An advisory has been issued which should help the problem
described in this bug report. This report is therefore being
closed with a resolution of ERRATA. For more information
on the solution and/or where to find the updated files,
please follow the link below. You may reopen this bug report
if the solution does not work for you.