Split for rhel3/2.1
+++ This bug was initially created as a clone of Bug #164927 +++
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 flaw has been rated as having a low severity by the Red Hat Security
Response Team. More information about this rating can be found here:
The risks associated with fixing this bug are greater than the low severity
security risk. We therefore currently have no plans to fix this flaw in Red Hat
Enterprise Linux 2.1 which is in maintenance mode
If you believe this judgement to be in error, please reopen this bug with an