Linux Tips and Tricks for Penetration Testing

General Linux tips for sudo access, text cleanup, shared folders and file transfers.

A grab-bag of general Linux tips that don’t belong to any one tool, but come up often enough during engagements to be worth keeping in one place.

Check sudo access

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cat /etc/group | grep sudo   # List members of the sudo group
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sudo cat /etc/sudoers        # Review sudo rules (requires sudo access)
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usermod -a -G sudo username   # Add a user to the sudo group

To let a user run a specific command without a password prompt, add a line like this to /etc/sudoers (via visudo):

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username ALL=NOPASSWD: /etc/init.d/ssh

Run a shell as another user (as root)

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su -c bash username

Show all completions on TAB instead of cycling through them

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sudo nano /etc/inputrc

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set completion-query-items 1000   # 0 = no limit

Mount a VMware shared folder in a Linux guest

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cd /mnt/hgfs/
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ls

If /mnt/hgfs/ doesn’t exist yet:

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sudo mkdir -p /mnt/hgfs
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sudo vmhgfs-fuse .host:/SharedFolder /mnt/hgfs -o allow_other   # Change "SharedFolder" to the name set in VMware

Clean up extracted text

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sudo sed -i -E 's|https?://||g' *.txt   # Strip http:// and https:// from every line in every .txt file

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# Count total characters across a text file
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awk 'BEGIN{FS=""}{for(i=1;i<=NF;i++)c++}END{print "total chars:"c}' wordlist.txt

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# Total line count across every .txt file in a folder
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wc -l *.txt | awk '{total += $1} END {print total}'

Convert a colon-delimited combo list to CSV

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{
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  echo '"URL","Username","Password"'
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  awk -F: '
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    NF==3 {
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      gsub(/\r/, "", $1); gsub(/\r/, "", $2); gsub(/\r/, "", $3);
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      gsub(/"/, "\"\"", $1); gsub(/"/, "\"\"", $2); gsub(/"/, "\"\"", $3);
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      printf "\"%s\",\"%s\",\"%s\"\n", $1, $2, $3
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    }
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  ' combolist.txt
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} > output.csv

Secure copy over SSH

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scp *.txt user@remote_host:/path/to/destination/

Linux Tips & Tricks