Ran EtreCheck and I have modified /etc/sudoers

EtreCheck tells me that /etc/sudoers has been modified. My rudimentary knowledge of Linux tells me that sudo is a command that allows a user to temporarily elevate their privileges to do something, and I definitely did not edit the file as I wouldn't dare do anything to it.

I recently had to erase my drive and do a clean reinstall of Yosemite due to an unwanted presence on my Macbook, and I only selectively restored my music, books and pictures from a previous TM backup (not any of the settings/applications/library etc). I've only been running this new system for 2/3 days. Is this change in the sudo file something I should be concerned about, in that wiping my Macbook clean didn't get rid of the unwanted presence?

This is my EtreCheck report (before anyone asks I will be uninstalling Avast ASAP!):

EtreCheck version: 2.4.1 (137)

Report generated 9/3/15, 10:24 AM

Download EtreCheck from http://etresoft.com/etrecheck

Click the [Click for support] links for help with non-Apple products.

Click the [Click for details] links for more information about that line.

Hardware Information: (What does this mean?)

MacBook Pro (Retina, 13-inch, Early 2013) (Technical Specifications)

MacBook Pro - model: MacBookPro10,2

1 3 GHz Intel Core i7 CPU: 2-core

8 GB RAM Not upgradeable

BANK 0/DIMM0

4 GB DDR3 1600 MHz ok

BANK 1/DIMM0

4 GB DDR3 1600 MHz ok

Bluetooth: Good - Handoff/Airdrop2 supported

Wireless: en0: 802.11 a/b/g/n

Battery: Health = Normal - Cycle count = 224 - SN = C012382060EDY3N7D

Video Information: (What does this mean?)

Intel HD Graphics 4000

Color LCD 2560 x 1600

System Software: (What does this mean?)

OS X 10.10.5 (14F27) - Time since boot: less than an hour

Disk Information: (What does this mean?)

APPLE SSD SM512E disk0 : (500.28 GB) (Solid State - TRIM: Yes)

EFI (disk0s1) <not mounted> : 210 MB

Recovery HD (disk0s3) <not mounted> [Recovery]: 650 MB

Untitled (disk1) / : 499.05 GB (333.65 GB free)

Core Storage: disk0s2 499.42 GB Online

USB Information: (What does this mean?)

Apple Inc. iPhone

Apple Inc. BRCM20702 Hub

Apple Inc. Bluetooth USB Host Controller

Apple Inc. Apple Internal Keyboard / Trackpad

Apple Inc. FaceTime HD Camera (Built-in)

Thunderbolt Information: (What does this mean?)

Apple Inc. thunderbolt_bus

Configuration files: (What does this mean?)

/etc/sudoers - Modified

Gatekeeper: (What does this mean?)

Mac App Store and identified developers

Kernel Extensions: (What does this mean?)

/Library/Application Support/Avast/components/fileshield/unsigned

[loaded] com.avast.AvastFileShield (2.1.0 - SDK 10.10) [Click for support]

/Library/Application Support/Avast/components/proxy/unsigned

[loaded] com.avast.PacketForwarder (2.0 - SDK 10.10) [Click for support]

Launch Agents: (What does this mean?)

[failed] com.avast.secureline.update-agent.plist [Click for support] [Click for details]

[running] com.avast.update-agent.plist [Click for support]

[loaded] com.avast.userinit.plist [Click for support]

Launch Daemons: (What does this mean?)

[loaded] com.avast.init.plist [Click for support]

[loaded] com.avast.uninstall.plist [Click for support]

[loaded] com.avast.update.plist [Click for support]

[loaded] com.barebones.authd.plist [Click for support]

[loaded] com.microsoft.office.licensing.helper.plist [Click for support]

User Launch Agents: (What does this mean?)

[loaded] com.avast.home.userinit.plist [Click for support]

[loaded] com.google.keystone.agent.plist [Click for support]

User Login Items: (What does this mean?)

Flux Application (/Applications/Flux.app)

iTunesHelper Application (/Applications/iTunes.app/Contents/MacOS/iTunesHelper.app)

Dropbox Application (/Applications/Dropbox.app)

Google Chrome Application (/Applications/Google Chrome.app)

Internet Plug-ins: (What does this mean?)

Default Browser: Version: 600 - SDK 10.10

QuickTime Plugin: Version: 7.7.3

SharePointBrowserPlugin: Version: 14.5.4 - SDK 10.6 [Click for support]

3rd Party Preference Panes: (What does this mean?)

None

Time Machine: (What does this mean?)

Skip System Files: NO

Mobile backups: OFF

Auto backup: NO - Auto backup turned off

Volumes being backed up:

Untitled: Disk size: 499.05 GB Disk used: 165.40 GB

Destinations:

M1 [Local]

Total size: 300.00 GB

Total number of backups: 2

Oldest backup: 2015-09-01 13:00:32 +0000

Last backup: 2015-09-02 23:55:57 +0000

Size of backup disk: Too small

Backup size 300.00 GB < (Disk used 165.40 GB X 3)

Top Processes by CPU: (What does this mean?)

17% Google Chrome Helper(14)

8% Google Chrome

4% WindowServer

3% hidd

2% fontd

Top Processes by Memory: (What does this mean?)

1.61 GB Google Chrome Helper(14)

646 MB kernel_task

229 MB Google Chrome

197 MB mdworker(8)

172 MB com.avast.daemon

Virtual Memory Information: (What does this mean?)

324 MB Free RAM

7.68 GB Used RAM (1.92 GB Cached)

60 MB Swap Used

Diagnostics Information: (What does this mean?)

Sep 3, 2015, 09:30:53 AM Self test - passed

Sep 1, 2015, 10:19:27 PM ~/Library/Logs/DiagnosticReports/Last.fm Scrobbler_2015-09-01-221927_[redacted].crash

Sep 1, 2015, 09:14:11 PM ~/Library/Logs/DiagnosticReports/com.apple.internetaccounts_2015-09-01-211411_[ redacted].crash

Sep 1, 2015, 09:16:48 PM ~/Library/Logs/DiagnosticReports/com.apple.preferences.icloud.remoteservice_201 5-09-01-211648_[redacted].crash

Anyway, someone else on the board posted what a regular Yosemite system should look like. My sudo file is below and I've highlighted things in red that are not in the sudoers file in a regular Yosemite set up:

## sudoers file.

##

## This file MUST be edited with the 'visudo' command as root.

## Failure to use 'visudo' may result in syntax or file permission errors

## that prevent sudo from running.

##

## See the sudoers man page for the details on how to write a sudoers file.

##

##

## Host alias specification

##

## Groups of machines. These may include host names (optionally with wildcards),

## IP addresses, network numbers or netgroups.

# Host_Alias WEBSERVERS = www1, www2, www3

##

## User alias specification

##

## Groups of users. These may consist of user names, uids, Unix groups,

## or netgroups.

# User_Alias ADMINS = millert, dowdy, mikef

##

## Cmnd alias specification

##

## Groups of commands. Often used to group related commands together.

# Cmnd_Alias PROCESSES = /usr/bin/nice, /bin/kill, /usr/bin/renice, \

# /usr/bin/pkill, /usr/bin/top

##

## Defaults specification

##

Defaults env_reset

Defaults env_keep += "BLOCKSIZE"

Defaults env_keep += "COLORFGBG COLORTERM"

Defaults env_keep += "__CF_USER_TEXT_ENCODING"

Defaults env_keep += "CHARSET LANG LANGUAGE LC_ALL LC_COLLATE LC_CTYPE"

Defaults env_keep += "LC_MESSAGES LC_MONETARY LC_NUMERIC LC_TIME"

Defaults env_keep += "LINES COLUMNS"

Defaults env_keep += "LSCOLORS"

Defaults env_keep += "SSH_AUTH_SOCK"

Defaults env_keep += "TZ"

Defaults env_keep += "DISPLAY XAUTHORIZATION XAUTHORITY"

Defaults env_keep += "EDITOR VISUAL"

Defaults env_keep += "HOME MAIL"

Defaults lecture_file = "/etc/sudo_lecture"

##

## Runas alias specification

##

##

## User privilege specification

##

root ALL=(ALL) ALL

%admin ALL=(ALL) ALL

## Uncomment to allow members of group wheel to execute any command

# %wheel ALL=(ALL) ALL

## Same thing without a password

# %wheel ALL=(ALL) NOPASSWD: ALL

## Uncomment to allow members of group sudo to execute any command

# %sudo ALL=(ALL) ALL

## Uncomment to allow any user to run sudo if they know the password

## of the user they are running the command as (root by default).

# Defaults targetpw # Ask for the password of the target user

# ALL ALL=(ALL) ALL # WARNING: only use this together with 'Defaults targetpw'

## Read drop-in files from /private/etc/sudoers.d

## (the '#' here does not indicate a comment)

#includedir /private/etc/sudoers.d

When I run the $ sudo ls -ale@ /private/etc/sudoers command in Terminal, I get:

-r--r----- 1 root wheel 2299 25 Jul 14:34 /private/etc/sudoers

Shouldn't the 4 digit number be 1275?

I don't know how to interpret any of this. Should these differences be a source of worry?