Inside the most innocent-looking image, a breathtaking landscape, or a funny meme, something dangerous could be hiding, waiting for its moment to strike.
No strange file names. No antivirus warnings. Just a harmless picture, secretly concealing a payload that can steal data, execute malware, and take over your system without a trace.
This is steganography, a cybercriminal’s secret weapon for concealing malicious code inside harmless-looking files. By embedding data within images, attackers evade detection, relying on separate scripts or processes to extract and execute the hidden payload.
Let’s break down how this works, why it’s so dangerous, and most importantly, how to stop it before it’s too late.
Steganography is the practice of concealing data within another file or medium. Unlike encryption, which scrambles data to make it unreadable, steganography disguises malicious code inside harmless-looking images, videos, or audio files, making it nearly invisible to traditional security tools.
In cyberattacks, adversaries embed payloads into image files, which are later extracted and executed on the victim’s system.
Why cybercriminals use steganography:
Let’s have a look at a malware campaign analyzed inside the ANY.RUN Interactive Sandbox that showcases exactly how steganography can be used in a multi-stage malware infection.
View analysis session with XWorm
We see inside ANY.RUN’s sandbox session that it all begins with a PDF attachment. The document includes a malicious link that tricks users into downloading a .REG file (Windows Registry file).
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At first glance, this might not seem dangerous. But opening the file modifies the system registry, planting a hidden script that executes automatically when the computer restarts.
Once the .REG file is executed, it silently injects a script into the Windows Autorun registry key. This makes sure that the malware launches the next time the system reboots.
At this stage, no actual malware has been downloaded yet, just a dormant script waiting for activation. This is what makes the attack so sneaky.
After a system reboot, the registry script triggers PowerShell, which downloads a VBS file from a remote server.
Inside the ANY.RUN sandbox, this process is visible on the right side of the screen. Clicking on powershell.exe reveals the file name being downloaded.
At this stage, there is no obvious malware, just a script fetching what appears to be a harmless file. However, the real threat is concealed within the next step, where steganography is used to hide the payload inside an image.
Instead of downloading an executable file, the VBS script retrieves an image file. But hidden inside that image is a malicious DLL payload.
Using offset 000d3d80 inside ANY.RUN, we can pinpoint where the malicious DLL is embedded in the image file.
Upon static analysis, the image appears legitimate, but when we inspect the HEX tab and scroll down, we find the <<BASE64_START>> flag.
Directly after this flag, we see “TVq,” the Base64-encoded MZ signature of an executable file. This confirms that steganography was used to conceal the XWorm payload inside the image, allowing it to bypass security detection until extracted and executed.
The final step of the attack involves executing the extracted DLL, which injects XWorm into the AddInProcess32 system process.
At this point, the attacker gains remote access to the infected machine, allowing them to:
Steganography-based attacks are a growing challenge for businesses, as traditional security tools often overlook hidden malware inside images and other media files. This allows cybercriminals to bypass detection, steal data, and infiltrate systems without triggering alarms.
With tools like ANY.RUN’s interactive sandbox, security teams can visually track every stage of an attack, uncover hidden payloads, and analyze suspicious files in real time:
Proactively monitoring suspicious activity and testing potential threats in a controlled environment is key to strengthening your cybersecurity posture.
Try ANY.RUN’s advanced features and gain deeper visibility into threats, and make faster, data-driven decisions to protect your business.
