Speaker 1: Welcome back to the deep dive. We're your shortcut to
Speaker 1: getting well, incredibly well informed without feeling totally overwhelmed.
Speaker 2: Yeah, there's a lot out there.
Speaker 1: There really is. So today we're diving into something powerful,
Speaker 1: maybe a bit underestimated, a kind of secret weapon that's
Speaker 1: actually been part of computing for decades. Foundational really exactly,
Speaker 1: but it's becoming super critical now in cybersecurity. Okay, let's
Speaker 1: unpack this. We are talking about cybersecurity operations, but maybe
Speaker 1: not with the fancy, expensive tools you might think of. First,
Speaker 1: we're talking about the command line.
Speaker 2: Ah, yes, good old command line, specifically the Bash Shehell.
Speaker 1: Our guide for this is a really practical book, Cybersecurity
Speaker 1: Ops with Bash, Attack, Defend and Analyze from the command
Speaker 1: Line by Paul Truncone and Carl Alvin. Great resource, totally,
Speaker 1: and our mission today is to give you a shortcut
Speaker 1: a way to see how Bash isn't just you know,
Speaker 1: for developers coding away or cised men's managing servers. It's
Speaker 1: this incredibly flexible multi tool anyone interested in computer security,
Speaker 1: whether you're on the offense probing systems or on defense
Speaker 1: building walls, attack or defend. Yeah, and the cool thing
Speaker 1: is the techniques work, whether you're on Linux, mac Os,
Speaker 1: even Windows these days.
Speaker 2: And what's truly fascinating here, I think is just how
Speaker 2: fundamental the command line is. I mean, most of us, right,
Speaker 2: we spend our time clicking around in graphical interfaces. Guisappoint
Speaker 2: click and they're great, super easy to use, no doubt,
Speaker 2: but that ease it often costs you something speed, maybe flexibility,
Speaker 2: and you definitely get distanced from what the system is
Speaker 2: actually doing.
Speaker 1: Underneath, like a layer of abstraction exactly.
Speaker 2: GUIs are like that nice dashboard in your car. Looks good,
Speaker 2: tells you the basics, but the command line that's like
Speaker 2: lifting the hood. You're right there with the engine.
Speaker 1: Okay. I like that analogy, and this.
Speaker 2: Deep dive hopefully will kind of reconnect you to that
Speaker 2: raw power, show you that Bash is this direct, super
Speaker 2: efficient way to tap into everything your operating system can do.
Speaker 1: Getting under the hood. I like, yeah, So, okay, why
Speaker 1: Bash specifically for cybersecurity? It still feels a bit basic.
Speaker 2: Well, it's basic in the best sense, you know, it's foundational.
Speaker 2: It's universal. Bash started in the Unix and Linux world obviously,
Speaker 2: but it's just everywhere now. It's standard on macOS, and
Speaker 2: you can get it really easily on Windows is get
Speaker 2: Bash seguine or the Window subsystem for Linux WSL WSL. Yeah,
Speaker 2: which means the stuff we talk about today. These aren't
Speaker 2: niche skills. They are incredibly transferable. You learn the stuff once,
Speaker 2: you can probably use it almost any way you might
Speaker 2: need to secure a system or figure out what.
Speaker 1: Happened on one. Okay, So it's like the ultimate cross
Speaker 1: platform utility belt for security folks pretty much. But to
Speaker 1: really use that belt effectively, especially for tricky security tasks,
Speaker 1: we probably need to nail down some and core ideas first.
Speaker 1: What are the essential bits of Bash that make it
Speaker 1: so good for this?
Speaker 2: Yeah, definitely if we connect this to the bigger picture,
Speaker 2: the real power often comes from how Bash handles data,
Speaker 2: how it moves information around data streams exactly. Every program
Speaker 2: fundamentally has like three channels, one for input coming in stin,
Speaker 2: one for normal output going out strout, and one for
Speaker 2: error messages.
Speaker 1: Sure, okay, in out and oops.
Speaker 2: Yeah basically. But the magic and where Bash really shines
Speaker 2: for security work is redirection and piping.
Speaker 1: Right.
Speaker 2: This is what lets you chain simple commands together to
Speaker 2: build surprisingly powerful custom tools like right on the spot.
Speaker 1: So redirection is sending stuff places.
Speaker 2: Yep. You can send the normal output of a command
Speaker 2: straight into a file maybe command results dot out, or
Speaker 2: if you want to add to a file that's already there,
Speaker 2: you use up and it tended exactly and you can
Speaker 2: send just the error messages somewhere else. Maybe two aero
Speaker 2: loog dot txt, or combine both normal output and errors
Speaker 2: into one file with evan in handy, or just make
Speaker 2: output disappear entirely if you don't need it, send it
Speaker 2: to dubnel, kind of like a black hole for data. Okay,
Speaker 2: And one more really full one is t That command
Speaker 2: lets you see the output on your screen while it's
Speaker 2: also saving it to a file. Great for monitoring something
Speaker 2: live but also keeping a record.
Speaker 1: Right, see it and save it makes sense. And piping
Speaker 1: that's the connector right the symbol. That's the one.
Speaker 2: Piping takes the standard output from the command on the
Speaker 2: left and feeds it directly as the standard input to
Speaker 2: the command on the.
Speaker 1: Right, connecting the tools precisely.
Speaker 2: This is how you build those complex workflows from simple
Speaker 2: building blocks. It's like creating an assembly line for your
Speaker 2: data right there in the terminal okay, And one more thing.
Speaker 2: If you have a command that might take a while,
Speaker 2: like maybe pinging a machine constantly to see if it's up,
Speaker 2: you can run it in the background using the ampersand
Speaker 2: so like ping one two point one sixty eight point
Speaker 2: one point one and ping results do log. It just
Speaker 2: runs quietly, logs its output and gives you your prompt
Speaker 2: back immediately.
Speaker 1: Oh that's useful.
Speaker 2: Yeah, And you can check on those background tasks with
Speaker 2: the jobs command and bring one back to the foreground
Speaker 2: with FG if you need to interact with it.
Speaker 1: Got it.
Speaker 2: And beyond just moving data, remember Bash is a full
Speaker 2: on programming language too. You've got variables, you can read input,
Speaker 2: you have if statements, wild loops, functions, you can automate
Speaker 2: almost anything.
Speaker 1: That flexibility is huge. Okay, but here's something you mentioned
Speaker 1: in the book that seems to trip people up a lot. Honestly,
Speaker 1: it confused me at first too.
Speaker 2: Ah, let me guess shell patterns versus regular expressions.
Speaker 1: Bingo. It gets really interesting here. What's the fundamental difference
Speaker 1: and why is getting them mixed up such a potential
Speaker 1: problem in security?
Speaker 2: It's a great question, and yeah, it is critical for
Speaker 2: doing things accurately. So shell patterns think for match anything,
Speaker 2: for match any single character for a range like a
Speaker 2: ZA right the file globbing stuff exactly. They're primarily designed
Speaker 2: for matching filenames in the filesystem. When you type ls
Speaker 2: dot log, you're telling the shell itself to find all
Speaker 2: filenames ending in dot log.
Speaker 1: Okay, so it's about the names of files, correct.
Speaker 2: Now. Regular expressions or rejects are different beasts, which more
Speaker 2: powerful patterns designed for matching text content stuff inside files
Speaker 2: or within a stream of data.
Speaker 1: Like searching inside a log file.
Speaker 2: Precisely. Rejects has a much richer, sometimes more complex set
Speaker 2: of special characters and rules. And you use rejects with
Speaker 2: tools that process text like rep or AUC or said.
Speaker 1: So, different tools, different patterns, yeah.
Speaker 2: And confusing them. That can lead to you missing crucial
Speaker 2: evidence because you used a file name pattern to search
Speaker 2: file content, or maybe doing something unintended because your pattern
Speaker 2: match files you didn't expect.
Speaker 1: Can you give a quick example, sure.
Speaker 2: Find varlogdash name dot gz uses a show pattern dot
Speaker 2: gz to find filenames ending in GZ.
Speaker 1: Simple okay, But.
Speaker 2: Grep error zerosh nine plus farlow gap dot log uses
Speaker 2: a regular expression error zero zero nine plus to find
Speaker 2: lines inside the app dot log file that contain the
Speaker 2: word error followed by one or more digits.
Speaker 1: Ah, Okay, one looks at the label, the other looks
Speaker 1: inside the box.
Speaker 2: That's a great way to put it. Understanding that difference
Speaker 2: is vital for precise investigation.
Speaker 1: Definitely. Okay. Let's shift gears into our first deep dive
Speaker 1: area defensive security operations with Bash. Using Bash as the
Speaker 1: investigator's toolkit, how do we usually frame defensive thinking?
Speaker 2: Well, A really helpful framework is the five principles of
Speaker 2: cybersecurity Confidentiality, integrity, availability, non repudiation, and authentication, often called
Speaker 2: CIANA for short CIA. Briefly, confidentiality is about keeping secrets
Speaker 2: secret only authorized access. Integrity means making sure data hasn't
Speaker 2: been messed with it's trustworthy. Availability is ensuring systems and
Speaker 2: data are there when you need them right. Non Repudiation
Speaker 2: is about proof linking in action to a specific user
Speaker 2: so they can't deny it. And authentication is simply proving
Speaker 2: you are who you say you are.
Speaker 1: Okay, the core security goals.
Speaker 2: Exactly, So the important question for us becomes, how does Bash,
Speaker 2: this command line tool actually help us maintain these principles,
Speaker 2: or maybe more importantly, how does it help us investigate
Speaker 2: when we suspect one of them has been violated?
Speaker 1: That makes sense. It grounds what we're doing. So if
Speaker 1: we're thinking about actually doing defense or investigating an incident,
Speaker 1: say checking data integrity or figuring out the confidentiality impact
Speaker 1: of a breach, Bash becomes our hands on toolkit. Where
Speaker 1: do we start maybe data collection and analysis.
Speaker 2: Absolutely, when something happens you need to gather evidence quickly
Speaker 2: and thoroughly. Bash gives you these direct tools. You've got
Speaker 2: simple things like cut to pull out specific columns of
Speaker 2: data file to quickly tell you what kind of file
Speaker 2: you're looking at, header tail to peak at the starter
Speaker 2: end of logs. The basics, the powerful, basic, And what's
Speaker 2: really neat is this isn't just a Linux Mac thing.
Speaker 2: If you're using git Bash on a Windows machine, you
Speaker 2: can call native Windows command line tools directly, things like
Speaker 2: reg to query the Windows registry oh wow, or web
Speaker 2: toodle to work with Windows event logs. You can investigate
Speaker 2: Windows systems using the same Bash skills. That cross platform
Speaker 2: ability is a huge win for analysts.
Speaker 1: So you're not constantly switching mental gears between operating systems.
Speaker 1: What about grabbing log files, say for later analysis.
Speaker 2: Super efficient. On Linux, you can package up all the
Speaker 2: logs in varlog into one compressed file, like sealing an
Speaker 2: evidence bag, with a command like tarh ccf O scs
Speaker 2: ez name logs, dot tr dot gz varlog easy.
Speaker 1: Nice.
Speaker 2: On Windows, you can script webtoodle to export all the
Speaker 2: different event logs. And here's a really powerful technique for
Speaker 2: remote systems, dotsh.
Speaker 1: It cure shell.
Speaker 2: Yeah, you don't even need to log into the remote machine.
Speaker 2: Sometimes you can run a command remotely like swash user
Speaker 2: at remote server command and get the output back on
Speaker 2: your local machine, or even run a local script on
Speaker 2: the remote machine like swash user at remote server, Bash,
Speaker 2: dash s dot mylocalscript, dot sh The script itself never
Speaker 2: has to be copied over there. It's efficient and sometimes stealthier.
Speaker 1: Okay, that's very cool for quick data grabs. So once
Speaker 1: you have the data, maybe logs or files from a system,
Speaker 1: it can be a lot of data. How do you
Speaker 1: start searching through it effectively? With Bash?
Speaker 2: Yeah, finding the needle in the haystack. Bash's fine command
Speaker 2: is your go to for searching based on filenames and
Speaker 2: other file attributes.
Speaker 1: Like finding suspicious file.
Speaker 2: Names exactly find dash name password. Could search the whole
Speaker 2: system for files with password in the name, use in
Speaker 2: name for case insensitive, or find hitting files which often
Speaker 2: start with a dot on Linux or Mac fine home
Speaker 2: name maagine. Remember that dot is a shell pattern matching
Speaker 2: file names starting with a dot.
Speaker 1: Got it filenames? What about searching inside the files for
Speaker 1: keywords or indicators.
Speaker 2: That's where GRIP comes in. Grap ir some directory suspicious pattern.
Speaker 2: The I makes it case insensitive, R makes it recursive
Speaker 2: through directories, and E specifies the pattern, which would typically
Speaker 2: be a regular expression here that you're looking for within
Speaker 2: the files.
Speaker 1: Okay, find for names grap for content makes sense. What
Speaker 1: about checking if files have been tampered with that integrity piece?
Speaker 2: Ah? Yes, Message digests or hashes tools like chess on
Speaker 2: some or md fivesome creator a unique digital fingerprint for
Speaker 2: a file. I could check some sort of but much
Speaker 2: more cryptographically strong. The key property is that changing even
Speaker 2: one single bit in the file will produce a completely
Speaker 2: different hash value.
Speaker 1: Wow.
Speaker 2: Okay, So if you calculate the hash of a critical
Speaker 2: system file and compare it to a known good value,
Speaker 2: you can tell instantly if it's been modified. It's a
Speaker 2: fundamental integrity check. You can script Bash to check hashes
Speaker 2: of many files very quickly.
Speaker 1: Powerful stuff. Okay, moving on to data processing and analysis.
Speaker 1: You've collected logs, maybe found some interesting files. How does
Speaker 1: Bash help make sense of, say a massive web server log.
Speaker 2: This is where combining tools with pipes really shines. Think
Speaker 2: about an Apache Access dot log, huge file, lots of lines. Right,
Speaker 2: you can use cut to extract just the IP address
Speaker 2: a the first field, then pipe that into sort, then
Speaker 2: pipe that into unique miss to count occurrences, and finally
Speaker 2: pipe that into sort. Dice on to see which ips
Speaker 2: made the most requests. Four simple commands chained together give
Speaker 2: you a top talkers list.
Speaker 1: It's pretty neat turning raw logs into a summary exact.
Speaker 2: Or you could use ak, which is brilliant for field
Speaker 2: based processing. Maybe you want to find which ips are
Speaker 2: getting lots of four O four not found errors, AC
Speaker 2: nine dollars easials four O four print one dollar. Access
Speaker 2: dot log could print the IP address field one from
Speaker 2: lines where the status code field nine is four oh four.
Speaker 2: Pipe that through your sertunic chain again.
Speaker 1: Help spot reconnaissance scanning.
Speaker 2: Maybe could be or maybe you want to see who's
Speaker 2: transferring the most data, use cut or ok to get
Speaker 2: the IP address and the number of bytes transferred. Then
Speaker 2: use another script maybe like the summer chistish example from
Speaker 2: the book, to total the bytes per IP. Sort that
Speaker 2: and a huge spike for one IP that might warrant
Speaker 2: investigation for data exultration.
Speaker 1: Right, checking the confidentiality wasn't breached precisely, and you can
Speaker 1: even visualize this stuff simply in the terminal.
Speaker 2: The book has examples like histogram dot ash that can
Speaker 2: take counts or totals and draw basic bar charts right there.
Speaker 2: Quick visual checks.
Speaker 1: Very cool. Okay. One more defensive area real time log monitoring,
Speaker 1: watching things as they happen.
Speaker 2: Yeah, super important for catching things early. The classic command
Speaker 2: here is tail dash F PATHTOLG file follow the file right.
Speaker 2: It just sits there and prints new lines as they
Speaker 2: get added to the end of the file. But the
Speaker 2: real power comes when you pipe that live stream.
Speaker 1: Ah pipe tail dash f output.
Speaker 2: Yes, pipe it into rep or egrep using the line
Speaker 2: buffered options, so it processes each line immediately, and you
Speaker 2: can filter that live stream for keywords or patterns so
Speaker 2: you can.
Speaker 1: Watch for specific errors or maybe log in attempts exactly.
Speaker 2: You could even build a simple lightweight intrusion detection system
Speaker 2: and IDs have a file say ioc dot txt with
Speaker 2: known bad patterns indicators of compromise like attempts to access
Speaker 2: sensitive files et cetera, paswd, or run commands pinch. Then
Speaker 2: you tail dash f your weblog and pipe it into
Speaker 2: egrep lineh buffer dash fioc dot txt. It will only
Speaker 2: show you the lines that match your bad patterns, alerting
Speaker 2: you in real time.
Speaker 1: Wow. Okay, a homegrown IDs with just tail.
Speaker 2: And rep pretty much, and you can do similar things
Speaker 2: on Windows. The book has a windtail dot sh script
Speaker 2: that uses web toodle in a loop to simulate tail
Speaker 2: dash f for Windows event logs.
Speaker 1: Bringing that real time view to Windows logs too.
Speaker 2: And you can take it further. There are scripts like
Speaker 2: webdash dot sh that use terminal control commands to create
Speaker 2: simple dashboards. They repeatedly run several commands, maybe monitoring different
Speaker 2: logs or system stats, and repaint the screen, giving you
Speaker 2: multiple live views in one terminal window.
Speaker 1: Okay, so Bash is definitely a powerhouse for defense and investigation.
Speaker 1: Let's flip the coin now penetration testing with Bash. Thinking
Speaker 1: like an adversary. How does Bash fit into the attacker's toolkit?
Speaker 1: Is there a structure they follow?
Speaker 2: Often yes, especially for more organized attackers. It's rarely just
Speaker 2: random hacking. A useful model to understand the phases is
Speaker 2: Mandiance attack life cycle. It lays out typical steps.
Speaker 1: Okay, where are they?
Speaker 2: There are about eight phases in that model. Reconnaissance first,
Speaker 2: then initial exploitation, establish foothold, escalate, privileges internal reconnaissance, move
Speaker 2: laterally inside the network, maintain presence, and and finally complete
Speaker 2: the mission whatever.
Speaker 1: That might be. Recon exploit foothold, escalate, internal recon lateral movement,
Speaker 1: maintain complete. Got it?
Speaker 2: Understanding that flow helps you see where tools including bashcripts
Speaker 2: might be used. It gives context to offensive actions. Bash
Speaker 2: makes an attacker very agile within this cycle.
Speaker 1: That framework definitely helps visualize it. Given how quick and
Speaker 1: low profile Bash can be, where does it really shine
Speaker 1: in this attack cycle? Let's start at the beginning. Reconnaissance.
Speaker 2: Reconnaissance is all about gathering intel in the target. Bash
Speaker 2: is great here. You can use kerl for example, to
Speaker 2: download web pages, maybe follow redirects to l save the output.
Speaker 2: Basically crawl website looking for information or vulnerabilities.
Speaker 1: This is from the command line.
Speaker 2: Yeah, and another classic technique is banner grabbing. Lots of
Speaker 2: network services like web servers, HGTP file servers, FTP mail
Speaker 2: servers SMTP. They announce themselves with a banner when you.
Speaker 1: Connect, like a welcome message kind of.
Speaker 2: And that banner often reveals the software name and version,
Speaker 2: maybe even the operating system gold dust for an attacker
Speaker 2: looking for known exploits.
Speaker 1: And you can automate grabbing these banners with Bash absolutely.
Speaker 2: But here's where Bash gets really sneaky and powerful, something
Speaker 2: that surprises people. You don't always need a dedicated tool
Speaker 2: like telnet or nmap to connect to a port and
Speaker 2: see that banner. No, Bash itself has this built in capability.
Speaker 2: Using a special filepath deftcfos nameport.
Speaker 1: Wait, Bash can make TCP connections directly effectively.
Speaker 2: Yes, it's a fetcher of the show. So an attacker
Speaker 2: on a system where maybe tools like telnet are removed
Speaker 2: or blocked, they can still perform network reconnaissance using just
Speaker 2: built in Bash commands. The book shows an SMTP connect
Speaker 2: dotsh script that uses exec three DVTCP one twenty five
Speaker 2: dollars to open a connection to an SMTP server on
Speaker 2: port twenty five and read its banner. No external tools needed.
Speaker 1: WHOA Okay, that is sneaky, minimal.
Speaker 2: Footprint exactly, pure command line resourcefulness.
Speaker 1: Okay. So after recun the model had like establishing a foothold,
Speaker 1: getting persistence.
Speaker 2: Right right Once you're in, you want a way to
Speaker 2: stay in or get back in easily. NC or netcat
Speaker 2: is often called the Swiss Army knife for networking. You
Speaker 2: can use it to create simple listeners, nclap port or
Speaker 2: make outbound connections.
Speaker 1: For simple data transfer or shells.
Speaker 2: Yes, and one very common technique for footholds is a
Speaker 2: reverse shell, especially using.
Speaker 1: SSH versus SSH. How does that work?
Speaker 2: Instead of the attacker connecting into the target, which might
Speaker 2: be blocked by a firewall, the compromised target machine initiates
Speaker 2: an outbound SSH connection to the attacker's machine using the
Speaker 2: natch R option SSR one two three four five dot
Speaker 2: local host part two to two attacker at attacker. This
Speaker 2: punches a hole out through the firewall. The attacker then
Speaker 2: connects to port one two three four five on their
Speaker 2: own machine, and SSH tunnels that connection back to the
Speaker 2: SSH server on the compromise targetqwever bypasses inbound rules very common.
Speaker 2: You can also create simpler, though less secure back doors
Speaker 2: just with Bash redirection and that devtsap trick again, something
Speaker 2: like exec binbash zero one one in two, two in
Speaker 2: one combined with connecting input output to a network socket
Speaker 2: instant remote shell Wow. Big warning though that kind of
Speaker 2: simple Bash backdoor. It's usually plain text unencrypted. Anyone stuffing
Speaker 2: the network can see everything risky, very so attackers might
Speaker 2: develop more sophisticated custom tools, maybe like the local rat
Speaker 2: dot show listener and remote rat dot ish client examples
Speaker 2: which use Bash scripting to provide more robust command execution
Speaker 2: and even file transfer capabilities over their backdoor channel.
Speaker 1: Makes sense now. If attackers are using these tools, they
Speaker 1: probably don't want defenders easily figuring them out if they
Speaker 1: get caught. That brings us to script obfuscation.
Speaker 2: Exactly, if your penetration testing script or your back door
Speaker 2: gets found, you don't want the blue team immediately understanding
Speaker 2: exactly how it works and what it did. Obfuscation makes
Speaker 2: reverse engineering harder.
Speaker 1: How do you obfuscate a Bash script?
Speaker 2: Several ways? Syntax obfuscation is the simplest. Just make the
Speaker 2: code hard to read. Put the whole script on one
Speaker 2: giant line, separated by semicolons. Use really meaningless variable and
Speaker 2: function names like afrioco.
Speaker 1: Or funky one annoying to read. That's the point.
Speaker 2: Then there's logic offuscation. This is where you add tons
Speaker 2: of useless code, pointless variables, functions calling other functions that
Speaker 2: do nothing important, complex loops that calculate something trivial. Makes
Speaker 2: a simple script look incredibly.
Speaker 1: Complicated, like hiding a needle in a bigger messier astac.
Speaker 2: Pretty much, but the most effective method is usually encryption. Okay,
Speaker 2: The basic idea is you have your real script plaintext.
Speaker 2: You encrypt it using a key producing ciphertext. You can
Speaker 2: use standard tools like ohensolars two thousand, CBC sll inrelscript
Speaker 2: dot sa outencrypted dot dot dot a password. Then you
Speaker 2: create a small rapper script. This wrapper contains the encrypted
Speaker 2: data and the password or prompts for it. When run,
Speaker 2: the rapper decrypts the real script into memory importantly, often
Speaker 2: without writing the decrypted version to disc, and then executes
Speaker 2: it using something like Bash open.
Speaker 1: Soli executes from memory much harder to recover the original script,
Speaker 1: much harder.
Speaker 2: Bash, which can even be used to demonstrate simple xor
Speaker 2: stream ciphers like the stream cipher dot sh example, using
Speaker 2: the random variable and a seed for educational purposes, showing
Speaker 2: the principles involved fascinating.
Speaker 1: Okay, one more offensive technique fuzzing. What is that exactly?
Speaker 2: Fuzzing is basically throwing junk at a program to see
Speaker 2: if it breaks. It's an automated way to find vulnerabilities,
Speaker 2: particularly thing like buffer overflows.
Speaker 1: Buffer overflows where the program tries to stuff too much
Speaker 1: data into a small.
Speaker 2: Space exactly classic C programming vulnerability With functions like strikeat
Speaker 2: they copy data from one place to another, but don't
Speaker 2: always check if the destination has enough room. If you
Speaker 2: send way too much data, it spills over overwriting adjacent memory,
Speaker 2: potentially crashing the program, or worse, allowing an attacker to
Speaker 2: inject malicious code. So a fuzzer, often just a simple script,
Speaker 2: systematically sends slightly different, often invalid or overly long inputs
Speaker 2: to the target program. The book has an example fuzzer
Speaker 2: dot is sha targeting a vulnerable C program fuzzme dot ex.
Speaker 2: The script just keeps sending longer and longer strings as
Speaker 2: command line arguments until fuzz me dot ex crashes. That
Speaker 2: crash point tells you roughly how much data causes the overflow.
Speaker 1: Automated vulnerability discovery yep.
Speaker 2: Bash is great for scripting that kind of repetitive testing.
Speaker 1: So we've seen Bash used for defense and offense. How
Speaker 1: do these two sides connect?
Speaker 2: Well? If we connect, this all back to the bigger picture.
Speaker 2: Understanding these attack methods is directly useful for defense. Knowing
Speaker 2: your enemy precisely. If you know how an attacker might
Speaker 2: use DEVTCP for banner grabbing or set up a reverse
Speaker 2: SSH tunnel, you know what kind of network traffic or
Speaker 2: process behavior to look for on your systems, you can
Speaker 2: figure firewalls better, maybe monitor for suspicious outbound connections. Knowing
Speaker 2: how a Bash backdoor works helps you spot those weird
Speaker 2: Bash processes talking over the network. Understanding fuzzing helps you
Speaker 2: appreciate why validating INP and properly in your own applications
Speaker 2: is so critical. Defense and offense really inform each other.
Speaker 2: Using Bash for offense gives you insight into how to
Speaker 2: use Bash for defense and vice versa.
Speaker 1: So what does this all really mean for you? The
Speaker 1: listener trying to learn this stuff? This deep dive? I
Speaker 1: think really Hammers home that Bash isn't just some utility
Speaker 1: for moving files around, not at all. It's this incredibly powerful,
Speaker 1: versatile language right at the heart of cybersecurity. Doesn't matter
Speaker 1: if you're Red Team or Blue Team. It's a foundational
Speaker 1: skill that just amplifies everything else.
Speaker 2: You do, which raises the important question, how can you
Speaker 2: actually practice these skills? Make them real?
Speaker 1: Good question? Reading is one thing doing as another exactly, And.
Speaker 2: The book actually has some really good practical workshop props
Speaker 2: to get you hands on. They're great starting points.
Speaker 1: Oh yeah, like what well?
Speaker 2: For example, you could try modifying one of the data
Speaker 2: collection scripts like get local dot shsh to automatically upload
Speaker 2: its findings to a secure server using CPP automate your
Speaker 2: evidence collection.
Speaker 1: Okay, practical.
Speaker 2: Or take the hash search dot s script, the one
Speaker 2: that finds files by their hash. Modify it so it
Speaker 2: stops searching as soon as it finds the first match.
Speaker 2: Make it more efficient, or maybe simplify the output paths
Speaker 2: it displays, tidying it up. Or for Windows, enhance the
Speaker 2: windlogs dot sh sh script to show a progress bar
Speaker 2: while it's working using tiput make it more user friendly.
Speaker 1: Nice little touches.
Speaker 2: On the offensive side. You could expand the fuzzer dot
Speaker 2: sh syncrypt to fuzz more than one command line argument
Speaker 2: at a time, make it a bit more thorough, or
Speaker 2: modify the banner grabber dot sh script instead of just
Speaker 2: one target, make it read a whole list of IPS
Speaker 2: from a file and output the results neatly into an
Speaker 2: htmel table for reporting. That sounds useful, and definitely try
Speaker 2: encrypting a simple script yourself using open sale or even
Speaker 2: the xor method and then write the rapper script to
Speaker 2: decrypt and run. It really helps understand that obfuscation technique.
Speaker 1: Get your hands dirty with encryption exactly.
Speaker 2: This kind of exercises really bridge that gap from just
Speaker 2: reading about it to actually doing it.
Speaker 1: Absolutely so, mastering the command line using Bash like this.
Speaker 1: It's not about throwing away your fancy graphical security tools, noah,
Speaker 1: not at all. It's about augmenting them, adding this fundamental
Speaker 1: layer of control and insight that maybe you didn't realize
Speaker 1: you had access to.
Speaker 2: Well said, I mean, the command line is your direct
Speaker 2: pipe to the OS. Right. All that power refined over
Speaker 2: decades in a world where we're increasingly using these slightly
Speaker 2: opaque GUIs understanding and being able to wield this direct power.
Speaker 2: That's not just another skill. It really is a critical
Speaker 2: advantage whether you're protecting systems or probing them, Which maybe
Speaker 2: leads to a final thought, what other lost arts, maybe
Speaker 2: in computing or even your own field, holds similar kinds
Speaker 2: of untapped power just waiting to be rediscovered.
Speaker 1: That's a great question to chew on something powerful hidden
Speaker 1: in plain sight. Well that's all the time we have
Speaker 1: for this deep dialk into cybersecurity ops with Bash. We
Speaker 1: hope you found it useful.
Speaker 2: Yeah, hope it sparks some ideas.
Speaker 1: Thanks for joining us, and we'll catch you on the
Speaker 1: next deep dive.