CentOS 7: Accidentally Secure by Being Obsolete

Level 1: Old Phone Immunity

Imagine you have a really old phone, like a flip phone from way back, and all your friends have the newest smartphones. Now suppose a new phone virus (a bad app or malware) starts infecting all the latest smartphones, making them act weird. Your friends are panicking, installing updates to fix their phones. But your little old flip phone? It’s absolutely fine – that virus can’t affect it at all, because it can only run on those fancy new smartphones. Your phone is too simple and too old for the virus to even work on it.

This meme is joking about something similar in the computer world. CentOS 7 is like that old phone. It’s an old computer operating system. New bugs and “viruses” came out that hurt newer systems (the fancy smartphones of computers), but CentOS 7 didn’t get hurt because it’s so old that those bugs don’t work on it – the new tricks just don’t apply. It’s like saying: sometimes being old-fashioned can save you from today’s trouble because you’re not involved in the new risky thing at all.

So the funny part is, usually old stuff is not considered very safe (just like an old phone might not have modern security features). But in this story, the old thing turns out to be the hero for the week, simply by being out of date. It’s a bit like a grandpa who avoids getting a new sickness going around because he never leaves his old house – he’s safe, but only because he’s not out there where the germs are. The meme makes us laugh because it’s backwards from what we expect: here, old and outdated = safe, just for this moment, which is a silly and surprising situation.

Level 2: Safe Because Ancient

Let’s break this down for those not steeped in sysadmin lore. CentOS 7 is an older version of a Linux operating system (CentOS is basically the free community version of Red Hat Enterprise Linux). It was super popular for servers in the 2010s. By 2023, it’s considered a legacy system – old, past official full support, and generally due for an upgrade. Now, normally running such an old OS is considered risky because it might not get updates anymore. But this meme jokes that for this particular week in 2023, being old was actually good for security. Why? Because the new security holes discovered that week don’t apply to software as old as what CentOS 7 has.

The tweet (by user @faker_) lists three lines with green check marks ✅:

• “cURL too old for CVE-2023-38545” – cURL is a widely used tool and library for transferring data with URLs (you use it to make web requests from the command line or in code). A CVE (Common Vulnerabilities and Exposures) is basically an ID for a specific security flaw. CVE-2023-38545 is a vulnerability found in 2023 affecting newer versions of cURL. When the tweet says “cURL too old,” it means CentOS 7’s version of cURL is so outdated that the vulnerability doesn’t exist in it. Imagine cURL as a book – the vulnerability was introduced in a chapter that was written after the edition that CentOS 7 has. CentOS 7’s cURL stopped at chapter 7, and the bug was in chapter 10, so to speak.

• “glibc too old for CVE-2023-4911 / Looney Tunables” – glibc stands for GNU C Library. It’s a core part of Linux systems, basically the helper library for C programs doing things like opening files, allocating memory, etc. It’s extremely crucial – if glibc has a flaw, it’s a big deal (because so many programs rely on it). CVE-2023-4911, nicknamed “Looney Tunables,” was a vulnerability discovered in 2023 in newer glibc versions. “Tunables” are a feature that let you configure certain low-level settings via environment variables (think of environment variables as little notes you can hand to programs to tweak their behavior). The “Looney Tunables” bug means if someone set a specially crafted environment variable, they could exploit a bug in glibc to potentially gain control (like an attacker on the same machine gaining root access – very bad). But CentOS 7’s glibc is old (version 2.17 from 2012). It doesn’t even have the Tunables feature at all! So it’s not vulnerable to this Looney Tunables bug simply because that part of the code isn’t there. It’s like having a car so old it doesn’t have a modern electronic ignition – you can’t hack the ignition computer if there isn’t one.

• “httpd too old for CVE-2023-44487 or any HTTP/2 support” – httpd here refers to Apache HTTP Server, a popular web server software (the program that serves web pages to your browser). HTTP/2 is the newer version of the HTTP protocol (which is what browsers and servers use to communicate). It brings features like multiplexing requests for speed, but also has added complexity. CVE-2023-44487 was a vulnerability in HTTP/2 discovered in 2023 (often called the “HTTP/2 Rapid Reset” attack). It let attackers overwhelm servers by abusing a feature of HTTP/2, effectively knocking them offline (a denial-of-service attack). Now, if your server doesn’t support HTTP/2 at all, you’re immune to this particular attack. CentOS 7’s Apache httpd is so old (the version is from around 2013) that it either doesn’t have HTTP/2 capability or it’s not enabled by default. In plain terms, CentOS 7’s web server speaks only the older HTTP/1.1 language and just ignores anything HTTP/2 related. So that whole fancy new attack is like speaking in an alien language to it – it doesn’t understand, and therefore it doesn’t crash from it.

So all three check-mark lines are saying: “CentOS 7 doesn’t have the new vulnerable stuff – hooray!” It’s a bit like bragging that your 20-year-old car is immune to a new kind of computer carjacking virus because, well, it doesn’t even have a computer.

Now, let’s add some context for each component and why it’s notable:

• CentOS 7: Released in 2014, and as an enterprise Linux, it typically stuck with older versions of software for stability. Companies used it because it was stable and supported for a long time. Even though official CentOS Linux is kind of discontinued (replaced by CentOS Stream and such), many servers still run it. It’s now considered a legacy operating system.

• Security Vulnerabilities (CVEs): When you see CVE-XXXX-YYYY, it’s an identifier for a specific security issue disclosed in year XXXX. For example, CVE-2023-38545 means it was disclosed/found in 2023, and it’s a unique number 38545. CVEs allow everyone to talk about the same bug with a common name. When you hear “there’s a CVE in glibc” it means glibc has a known security hole that usually needs patching.

• Outdated Packages: In CentOS 7, the versions of software (like cURL, glibc, httpd) are old. But in enterprise distros, they usually backport important fixes. “Backport” means they take a fix from a newer version and apply it to the older version without upgrading everything. This way, they keep stability (same old version interface) but fix critical issues. However, they don’t add new features. That means CentOS 7’s packages lack any feature added after ~2014. For instance, Apache httpd in CentOS7 doesn’t have HTTP/2 because HTTP/2 support was a feature added to Apache in a later release around 2015-2016.

• LegacySystems vs Modernization: This meme highlights a quirk in how we manage systems. “Legacy system” is a polite term for “old system that probably should be upgraded, but is still running because it works (or nobody wants to touch it).” Modernization means bringing systems up-to-date (new OS versions, new libraries, etc.), usually to get better performance, security updates, and features. However, in modernization you sometimes encounter new bugs or need to rewrite parts of your application to be compatible. It’s often a risk and effort, so some places delay it. The joke here is that such delay (running CentOS7 instead of a newer OS) unintentionally had a benefit: not being affected by the latest bugs that hit new systems.

Put simply, the meme is saying CentOS 7 is like the unlikely hero that saved the day by being old. It’s safe this week because the particular bad things (vulnerabilities) everyone is worried about target stuff that CentOS7 doesn’t have. This resonates with system administrators and developers because it’s usually the opposite – older systems are a headache, not a hero. Seeing it jokingly praised flips the script, which is funny in a nerdy way. It’s a bit of sysadmin humor: only in IT would being “too old” qualify as “ahead of the game,” even if just for a moment. And trust me, plenty of IT folks have had that experience where keeping an old setup running ended up avoiding some new catastrophe. They’ll chuckle at this while probably thinking, “Yeah… but I really should upgrade that box… maybe next week.”

Level 3: Too Old to Exploit

On a senior engineer or security professional level, the humor hits close to home. The tweet effectively says: “Our beloved CentOS 7 – though basically a fossil – turned out to be the MVP of security this week.” Why? Because all the big scary vulnerabilities everyone’s scrambling to patch don’t affect it, thanks to its outdated packages. It’s the classic irony: a system long past End-of-Life is immune to cutting-edge threats simply by being obsolete. This is often jokingly called security by obsolescence. Seasoned sysadmins have seen this pattern before and likely smirk in recognition.

Consider the recent chaos in October 2023 with those CVEs:

• A critical flaw in cURL had teams rushing to update their libcurl.
• The “Looney Tunables” bug in glibc had ops folks sweating, as it could allow local privilege escalation.
• The HTTP/2 Rapid Reset attack (CVE-2023-44487) led to emergency mitigations on modern web servers to fend off a novel DDoS vector.

Every security bulletin that week basically screamed “Patch now, or you’re in trouble!” Yet someone running CentOS 7 could cheekily say, “Patch what? My cURL is so ancient it doesn’t even have that bug. Glibc tunables? Never heard of ’em. HTTP/2? Not in my house.” It’s a facetious brag born from relief: for once, procrastination and technical debt paid off (or so it seems).

The humor works because it flips best practice on its head. Normally, running outdated software is considered a bad practice – it’s a ticking time bomb of known vulnerabilities and lack of support. But here we have a rare moment where being behind the times feels like a win. It’s like a tortoise-and-hare story in cybersecurity. Everyone who dutifully upgraded to the latest and greatest versions got hit by these new problems (the hare runs ahead and trips over new bugs), whereas the laggards on old systems (the tortoise) just plod along unaffected, wryly saying, “What’s all the fuss about?” 💁‍♂️

There’s an underlying commentary on the trade-offs between modernization and stability. Senior folks know that upgrading core infrastructure (like moving from CentOS 7 to 8 or Stream, updating glibc, etc.) is a double-edged sword. On one edge, you get new features, performance improvements, and usually better security hardening overall. On the other edge, you open yourself to fresh, undiscovered bugs and have to re-test everything. CentOS 7 represents the extreme end of “if it ain’t broke, don’t fix it.” Enterprises often cling to such LTS (Long Term Support) releases for years beyond their prime because they’re battle-tested and all the integration quirks are figured out. The meme exploits the fact that in such an environment, “new” problems often simply don’t apply.

Real-world ops example: A company still running its internal apps on CentOS 7 might have felt a bit smug that week. While others scrambled to apply emergency patches or mitigations (maybe taking down servers at 3 AM to update cURL or glibc), the CentOS 7 holdouts were sipping coffee, secure by default 🙃. Of course, they won’t be smug for long – an older system like that could have its own unpatched issues (and come next vulnerability wave, they might be in bigger trouble because official support has ended). But the meme’s green checkmarks (✅) next to each “too old for X CVE” line playfully list out these improbable advantages as if CentOS 7 just aced a security exam without even studying. It’s a shared joke among seasoned devs and sysadmins: “Sometimes your legacy system dodges bullets simply because it’s a dinosaur that doesn’t go where the shooting is.”

We also recognize a bit of dark humor about technical debt. Usually, running on decade-old libraries is a risk we document in red ink. But here that technical debt is momentarily portrayed as a heroic strength. It’s the inverse of the usual panic calls: “Update now or face the hacker music!” Instead, it’s “Don’t update, and you won’t even have that problem.” No one is seriously advocating to avoid updates as a security strategy, but the joke lands because every senior dev/op has had that wry thought when reading a new CVE report: “Hah, we’re still on the old version, so we’re not affected… Should we feel relieved or embarrassed?”

This hits on a common industry theme: version pinning and long-term support versus the pressure to stay current. CentOS (Community ENTerprise Operating System) 7 was released in 2014 and aligned with Red Hat Enterprise Linux 7. It’s been around nearly a decade, and in enterprise IT, you’ll find mission-critical systems stubbornly still running it. Upgrading those is often non-trivial – there are legacy apps, configurations, even hardware that might not play nice with newer OS versions. So teams delay and delay… and sometimes, like a stopped clock that’s right twice a day, that delay accidentally sidesteps a nasty issue. The meme exaggerates that scenario for comedic effect.

In summary, at the senior level we’re laughing with a bit of pain behind it. We’ve all overseen systems held together by duct tape and legacy code. We know the relief of “not my problem” when a hyped vulnerability drops – and the twist of irony when the reason is “oh, because we never upgraded that thing.” It’s a moment of vindication for every grizzled sysadmin who’s ever said, “See? Sometimes inertia is the best security policy!” (uttered with heavy sarcasm, of course). The tweet taps into that shared experience, making a hero out of what is normally a liability, and that role-reversal is pure comedic gold in the tech world.

Level 4: Stale Software Shield

At the deepest technical level, this meme riffs on the paradox of security through obsolescence – the idea that software can be safer because it’s outdated. It’s a tongue-in-cheek nod to attack surface theory: every new feature or code path (like HTTP/2 support in a web server, or new tunable parameters in a C library) introduces complexity and potential vulnerabilities. Here, CentOS 7 – an old Linux distribution – has frozen-in-time versions of key components (cURL, glibc, httpd). These versions are so ancient that they predate the recently disclosed vulnerabilities (identified by those CVE numbers). In other words, the vulnerable code simply does not exist in CentOS 7’s packages, making it immune by default. It’s an ironic application of the maxim: the most secure code is code that never runs (or in this case, was never written).

Let’s break down the CVEs mentioned, because each is tied to a specific feature absent in CentOS 7’s prehistoric toolkit:

• CVE-2023-38545 (cURL) – This was a high-profile flaw in cURL discovered in 2023. It affected modern cURL versions with new functionalities (possibly in how cURL parses certain URLs or handles specific protocols). CentOS 7 ships with curl 7.29.0 (from ~2013), a version so old it doesn’t include the code that later became vulnerable. Essentially, the exploit code path is missing entirely. No code, no vulnerability – legacy immunity in action.

• CVE-2023-4911 “Looney Tunables” (glibc) – A severe bug found in the GNU C Library (glibc) that earned a quirky nickname. It involved the glibc tunables feature – an environment-variable-based tuning mechanism added in newer glibc versions to tweak low-level settings. This Looney Tunables bug allowed a buffer overflow via malicious environment variables, leading to potential root privilege escalation. But CentOS 7’s glibc is version 2.17 (circa 2012), way before tunables were introduced. That antique glibc never learned these new tricks: no tunables support, no vulnerable code. It’s like the flaw is in a chapter that CentOS 7’s glibc never had in its book.

• CVE-2023-44487 (HTTP/2 Rapid Reset, affecting httpd) – A vulnerability exploiting the HTTP/2 protocol by bombarding servers with rapid “RESET” frames, causing a denial of service. Modern web servers (like newer Apache httpd builds, Nginx, etc.) that enabled HTTP/2 were caught off-guard by this clever attack on the protocol’s design. Yet CentOS 7’s Apache httpd is an old 2.4.x version from an era when HTTP/2 either didn’t exist or wasn’t enabled by default. In fact, the Apache version packaged with CentOS 7 (e.g. Apache 2.4.6) has no HTTP/2 support out of the box. Thus, the entire class of HTTP/2 vulnerabilities sails right past – you can’t exploit HTTP/2 on a server that speaks only HTTP/1.1!

From a systems theory perspective, this is all about reducing the attack surface. CentOS 7’s frozen dependencies act like a shield because they exclude entire categories of modern functionality that attackers target. It’s a funny inversion of the usual security narrative – normally, outdated software is riskier due to unpatched old bugs, but here outdated software is incidentally safer against new bugs that didn’t exist when it was written. We essentially have “security by antiquity,” where yesterday’s software can’t be harmed by today’s exploits if those exploits target innovations of the last decade.

Of course, this stale software shield comes with caveats. CentOS 7 might dodge this week’s zero-days, but it carries its own baggage of older CVEs (hopefully patched over time by backported fixes, but certainly a few skeletons in the closet). In the long run, relying on “too old to be hacked (in that way)” is a sketchy strategy – akin to a castle with outdated defenses: it might ignore cannon fire simply because it’s tucked away in a valley the cannons can’t reach, but it might also crumble from internal rot. Nonetheless, the meme humorously celebrates this one week where being a fossil was a superpower. It’s a nerdy tribute to the complex dance between software evolution and new vulnerabilities: if you stand perfectly still in time, sometimes the bullets of progress whiz right by.

// Pseudocode metaphor for CentOS 7's "immune" versions:
if (!hasFeature("HTTP2")) {
    // No HTTP/2 feature, hence not vulnerable to HTTP/2 Rapid Reset (CVE-2023-44487)
    safe_from_http2_havoc();
}

if (curl.version < vulnerable_version) {
    // cURL version is so old that CVE-2023-38545 code isn't present
    ignore_modern_curl_exploit();
}

if (!glibc.hasTunables()) {
    // glibc predates Looney Tunables, skip that exploit entirely
    laugh_in_ancient();
}

In essence, the meme highlights an accidental security model: “security by outdatedness.” It’s a real-world example of how legacy systems sometimes avoid the cutting-edge flaws simply by virtue of running code frozen in a bygone era. As seasoned engineers know, every new library upgrade or protocol enablement can be a double-edged sword – you get improvements, but you also open yourself up to the next CVE. CentOS 7 has basically been sitting out the feature race, and ironically, it sat out some new security vulnerabilities too. This deep-dive context is what makes the tweet wryly amusing to kernel hackers, security researchers, and sysadmins: it’s a joke with a core of truth about how modernization and risk oftentimes go hand-in-hand.