PPSideLoader: The Clever PowerPoint Backdoor Bypassing Your Security In the ever-evolving landscape of cybersecurity, attackers are constantly refining their techniques to slip past traditional defenses. One such method that has gained traction among Advanced Persistent Threat (APT) groups and cybercriminals is PPSideLoader . While the name sounds like a piece of malware, PPSideLoader is actually a technique —a specific method of sideloading malicious code using Microsoft PowerPoint files ( .pps or .ppsx ). Here is everything you need to know about how it works, why it is dangerous, and how to stop it. What is PPSideLoader? PPSideLoader is a DLL sideloading attack that leverages Microsoft PowerPoint’s slide show mode. In a standard DLL sideloading attack, an attacker tricks a legitimate application into loading a malicious Dynamic Link Library (DLL) file instead of the legitimate one. PPSideLoader takes this concept and applies it specifically to PowerPoint. Attackers package a malicious DLL alongside a legitimate PowerPoint executable (or related component). When PowerPoint runs a slideshow, it looks for specific supporting files. If an attacker has placed a poisoned DLL in the same directory, PowerPoint will load it—granting the attacker code execution on the victim’s machine. How It Works: Step-by-Step Unlike macro-based attacks (which require the user to enable scripts), PPSideLoader relies on file system behavior and search order hijacking. The typical attack chain looks like this:
The Lure: The victim receives a ZIP archive or a phishing email attachment containing two files:
A legitimate PowerPoint slide show file (e.g., Invoice_Details.ppsx ) A malicious DLL file (e.g., mscoree.dll or system.data.dll )
The Extraction: The victim extracts the archive to a local folder (e.g., their Downloads or Desktop). The Execution: The victim double-clicks the .ppsx file to open the presentation. The Hijack: When PowerPoint (POWERPNT.EXE) launches the slideshow, it follows Windows’ DLL search order. It looks first in the directory where the presentation is located. It finds the attacker’s malicious DLL and loads it into memory. The Payload: The malicious DLL runs code in the context of the legitimate PowerPoint process, bypassing application control policies and antivirus scanners that trust Microsoft-signed binaries. ppsideloader
Why Is This Technique So Effective? PPSideLoader is dangerous because it exploits trust and visibility gaps:
No Macros Required: Many organizations block macros by default. PPSideLoader requires no user interaction beyond opening the file. Living off the Land: It uses a legitimate Microsoft binary ( POWERPNT.EXE ) as the host process. Security teams often whitelist these processes, allowing the malicious activity to blend in. Bypasses Application Allowlisting: If your policy allows powerpnt.exe to run, and you don’t hash-check every DLL it loads, the attack will succeed. Evades Static AV: Traditional antivirus scans the .ppsx file, which is clean. The malicious payload is in a separate .dll file that may not be scanned until execution.
Real-World Examples Cybersecurity researchers have observed PPSideLoader being used by APT groups, including those targeting government and financial sectors in East Asia and Europe. In many observed campaigns: Here is everything you need to know about
The legitimate PowerPoint file was an unrelated, benign presentation. The malicious DLL acted as a loader for Cobalt Strike or a remote access trojan (RAT). The attack was delivered via spear-phishing with a password-protected ZIP file to evade email gateway scans.
Detection & Mitigation Because PPSideLoader abuses a legitimate feature, traditional blocking is difficult. Instead, focus on behavioral detection and hygiene. Detection Strategies:
Monitor for Unusual DLL Loads: Look for POWERPNT.EXE loading DLLs from non-standard paths (e.g., C:\Users\Public\ , C:\Temp\ , or the Downloads folder). File Creation Events: Alert on the simultaneous appearance of a .ppsx or .ppam file and a .dll with a suspicious name in the same directory. Network Egress: Even if the DLL loads, watch for powerpnt.exe making outbound connections to unknown IP addresses (a sign of beaconing). In a standard DLL sideloading attack, an attacker
Mitigation Steps:
Block Executables from Archives: Use email filtering to strip .dll , .exe , and .scr files from ZIP/RAR attachments, even if password-protected. Restrict DLL Search Order: Configure Windows to disable searching the current working directory for DLLs (via CWDIllegalInDllSearch registry key or Group Policy). Endpoint Detection & Response (EDR): Deploy EDR that can detect process injection and sideloading patterns, not just static file signatures. User Training: Teach users never to open PowerPoint files extracted from archives alongside mysterious ".dll" files. If a presentation comes with a DLL, it is an attack.