Updating or reverting a device's firmware seems as simple as "updating" it or "reverting it to its previous state," but the reality is much more complex. Every change to that internal software can affect the stability, safety and useful life from your mobile phone, your router, your server, or even your video surveillance cameras.
Many businesses and home users continue to use older firmware for fear that an update will break something: integration with other systems, data loss, or unexpected failures. However, leaving everything "as is" also comes at a price: malware risk and devices that literally turn into a brick if something goes wrong when reversing.
What is firmware really and why isn't it "just another update"?
Firmware is the low-level software that makes the hardware work: without it, the device won't even boot. It's located in routers, servers, mobile phones, printers, IP cameras, IoT and virtually any modern electronic device. Unlike a simple app, if you damage it, you don't have an "uninstall and go" button.
Manufacturers release new firmware versions for fix security flaws, fix bugs, and add featuresThese versions can modify how the device communicates with other systems, how manages memory, secure boot or even which operating systems it can run (in the case of mobiles and some servers).
Therefore, every firmware update—whether an upgrade or a rollback—involves touching the most critical part of the device. Any error during the update process or the rollback attempt can result in a software bricking. The device stops starting up, becomes unresponsive, and can only be recovered, if at all, through advanced procedures or technical service.
What does flashing and reverting firmware on a mobile phone mean?
In the context of a mobile phone, "flashing" firmware consists of manually install a system image (ROM) from a computer, using specific tools from the manufacturer or third parties. For example, on a Samsung Galaxy, this is often done with Odin and an official ROMOther manufacturers use fastboot, proprietary tools, or recovery modes.
A user with a Samsung Galaxy S9 stuck on Android 9 might wonder: “If I'm no longer receiving OTA updates, should I flash a newer ROM or try a different firmware region?” Technically, it's possible, but it's important to understand that flashing forces a reinstallation that skips certain automatic checks What does the system do when it updates through official channels?
In that same scenario, reverting to a previous version of Android or baseband would mean trying to go back to a previous version because the new version is worse, has bugs, or has removed features. That's where the... downgrade protections of the bootloader and the security mechanisms that can completely block that reverse gear.
Even if the user creates backups with Smart Switch or other tools, the risk remains. Incorrect firmware, a power outage, or a corrupted file can leave the device in a state where Even the standard recovery doesn't respond.Recovery, if possible, usually requires reflashing from scratch, and is not always within the reach of the average user.
Downgrade prevention: why your device won't let you revert to the old way of thinking
The so-called "downgrade prevention" is a set of mechanisms that prevent the installation of firmware on the device with a version number lower than the one already installed. It is usually implemented in the bootloader or boot manager and it acts even before the operating system boots up.
The process is automatic: when you try to flash, the bootloader compares the version identifier or "rollback index" of the new firmware with the one stored internally. If it detects that it's lower, it blocks the installation. In other cases, the manufacturer goes further and removes or invalidates digital signature keys associated with older versions. Thus, the system no longer even recognizes those previous firmwares as legitimate.
This translates into a dead end for the user. After a faulty update or one with unpopular changes, there is no longer an official route to... return to the previous stable stateIf performance drops, serious bugs appear, or features are lost, the user can only wait for a new patch. Or resign themselves and switch devices.
Manufacturers justify this downgrade prevention on the grounds of security and compatibility. They aim to prevent users from reverting to versions with known vulnerabilities and to avoid conflicts with new hardware or services. However, from the perspective of the right to repair and the real property over the deviceIt is perceived as a way of restricting the owner's freedom and, often, of accelerating planned obsolescence.
Specific risks of reverting firmware on mobile phones
When someone considers flashing or reverting firmware on an older mobile phone to continue receiving updates, they must assume several technical and legal risks. The first is the risk of partial or total brick. An incorrect, interrupted, or corrupted flashing process can render the device unusable.
Furthermore, even if the flashing seems to be working fine, there is always the possibility that other issues may arise. critical failures in retrospectLoss of coverage, baseband problems, cameras that stop working, extreme battery drain, or random boot errors. These symptoms may be due to minor incompatibilities between carrier firmware, region, or hardware.
To this we must add the issue of warranty. Although many phones that are flashed are already out of coverage, it's important to know that most manufacturers don't provide support or accept warranty claims for devices that have been modified at the firmware level. The simple fact of unlock the bootloader or install unofficial ROMs It usually invalidates any claim.
Another sensitive point is the firmware's origin. Not all sites offering ROMs are trustworthy, and downloading executable files or system images from unknown repositories opens the door to... Trojans or backdoorsWhenever possible, it is advisable to consult the manufacturer's official websites or reputable and verified community projects.
Finally, even after a successful flash, it's not guaranteed that the phone will receive OTA updates again. It depends on whether the installed firmware corresponds to a supported region and variantIn many cases, the user will be forced to manually repeat the process each time a new version is released.
Why not updating (or reverting) firmware is a security problem
The temptation to “don’t touch anything, it works” is understandable, especially in business environments where a service interruption is very costly. However, leaving the firmware unupdated for years turns devices into easy targets for cybercriminals.
Outdated firmware often contains documented security vulnerabilities and, worse, publicly available exploits. This means routers, switches, NAS devices, cameras, or servers can be easily compromised and used as security devices. botnet nodes, cryptocurrency miners or platforms to launch attacks against third parties.
Organizations like the FBI have even issued specific alerts about end-of-life (EOL) routers that no longer receive patches. One of these warnings details how variants of the TheMoon malware exploit unsupported routers without requiring a password; they simply... scanning open ports and calling vulnerable scripts unpatched.
Once compromised, these routers are resold as proxy services on platforms like Anyproxy or 5Socks, serving to conceal the identity of criminals who commit financial fraud, attack IoT devices, or even critical infrastructure. If the router stops receiving firmware updates, the only truly secure path is replace it with a supported model.
Something similar happens with other network devices and servers. Without regular firmware updates, any subsequent security layer (antimalware, segmentation, EDR) rests on a foundation riddled with cracks. Firmware is the first line of defense, and if it fails, everything else becomes ineffective.
Firmware update for cameras and security devices
Something very similar happens in the field of video surveillance. Many organizations are reluctant to install new firmware on IP cameras because they fear losing access. stability or compatibility with your management software (VMS)They prefer to stick with an older version that they "already know" rather than risk an update that will stop communicating with their system.
The problem is that these cameras, over time, accumulate serious vulnerabilities that can allow an attacker to view the images, pivot to other parts of the network, or integrate them into a botnet. Forgoing firmware maintenance to avoid a potential service outage exposes the company to much greater and sustained risks over time.
To resolve this conflict, some manufacturers have begun offering Long Term Support (LTS) firmware models. In these programs, LTS updates only include Important bug fixes and security patchesHowever, they do not introduce functional changes to the camera. In other words, they do not touch the features or APIs used by the VMS.
This way, organizations can keep their cameras secure without having to constantly readjust integrations. The "active" firmware mode, with new features and major changes, is still available for those who want the latest version, but alongside it runs a stable LTS branch, designed to prioritize service continuity.
LTS versions are typically released periodically, starting from the active reference firmware. Subsequent revisions of that branch only incorporate... stability improvements and vulnerability patchesThe customer can decide when to upgrade to a new LTS version, aligning that upgrade with other system updates or hardware changes.
How to design a secure update and rollback policy
In a company, updating or reverting firmware should not be an impulsive act, but a controlled and documented process. The first step is to have a clear inventory of all firmware and software in use: which versions are installed, which equipment models, which manufacturer and what life cycle each product has.
With this inventory in hand, the technical team can closely monitor security bulletins, release notes, and public alerts (e.g., RSS feeds, Google Alerts, or official notices from manufacturers and agencies like the FBI). This allows for the rapid detection of vulnerabilities. critical updates that need to be prioritized.
Before updating, the technical department should choose the right time to avoid disrupting business operations and assess the functional impact of each change. Whenever possible, a testing environment or laboratory where to first install the new firmware and check that everything works as expected.
It is equally essential to determine beforehand if there is a supported way to undo the update. Some manufacturers allow reverting to a previously signed version. Others activate downgrade prevention and close that door. If there is no rollback option, even more caution is necessary. strengthen backups and contingency plans.
Finally, keeping a record of all updates performed (device, date, previous and new version, test result) allows you to know at all times what is in production, facilitates audits and narrows down the origin of incidents when failures appear after a firmware change.
The dark side of not updating: end of support and obsolescence
Even with best practices, all firmware has a limited life cycleThere comes a point when the manufacturer declares a product to be end-of-life (EOL) and stops releasing patches, even for critical vulnerabilities. From then on, each month the device remains in production increases the cumulative risk.
At this point, reverting to previous versions no longer makes any sense from a security perspective. Neither the current version nor past versions are patched. Any attempt to "go back to the one that worked better" can only worsen the vulnerability, especially if those older versions don't even pass bootloader checks.
The sensible thing to do when a device reaches its end of life (EOL) is to plan its replacement with another model whose manufacturer guarantees several years of firmware supportwith regular updates and a clear differentiation between feature versions and security versions.
Some companies indefinitely postpone this decision due to initial costs, but end up paying much more if an outdated router, camera, or server serves as a gateway to a serious incident: data theft, ransomware encryption of systems, or widespread production shutdowns.
For individual users, something similar happens with older phones that are left without patches: while continuing to use the device for very basic tasks may be acceptable, doing so constantly connected to open WiFi networks, with sensitive apps, and without firmware or system patches is... play with fire.
In short, updating and, where necessary, reverting firmware is not a technical whim but a strategic decision: poorly managed, it can leave devices unusable or entire networks vulnerable to attacks; well planned, with backups, testing, LTS cycles and attention to end-of-support, it allows you to extend the useful life of the hardware without sacrificing security or system stability.
