Cat not read a file in linux, even when read permission is enabled
 

Hello. I am running debian lenny on my system. I am not able to read a file as root user (with any command), even when read permission is enabled or to list or change ext3 file system attributes either.

What does this mean, file corruption?

# ls -l file
-rwxrwxrwx 1 <user> <group> 609834 dic 15 18:49 <file>

# file file
<file>: writable, executable, regular file, no read permission


# cat file
cat: <file>: Operation not permitted

#cp file .

cp: can not read <file>: Operation not permitted.

I know that other possibility could be that the write system call was modified by a malicious rootkit. I checked my system with rkhunter and I found this:

Checking for string 'hdparm' [ Warning ]
I searched for this and it seems like a false positive.
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=561308

[11:12:20] Warning: Checking for possible rootkit strings [ Warning ]


[11:12:41] Checking for hidden files and directories [ Warning ]
[11:12:41] Warning: Hidden directory found: /dev/.udev
[11:12:41] Warning: Hidden directory found: /dev/.initramfs
https://bugs.launchpad.net/ubuntu/+s...er/+bug/219840

These seems like false positives too.
Any hints of why I can not read this file?

Thanks in advance.

What do commands
and
show?

Nominal Animal

Boot to live cd just to check it again. I suspect that the filesystem is bad or partition off or overlapping.