DLL hijacking is the broader technique of abusing Windows search and load order so an application loads a malicious library instead of the intended one. DLL sideloading is a common form of that abuse, usually involving a legitimate program tricked into loading a bad DLL from a nearby location. In practice, sideloading is one way hijacking is carried out.
How the terms differ in practice
dll hijacking is the umbrella abuse pattern: an application is induced to load a library other than the one its developer intended, often because of the Windows search order, unsafe paths, or weak DLL loading controls. dll sideloading is a narrower case within that pattern, where a legitimate, signed, or trusted executable is used as the delivery vehicle and a malicious DLL is placed beside it so the program loads the attacker-controlled code.
The practical distinction is not just vocabulary. Hijacking describes the broader loading weakness, while sideloading describes a common execution method that leverages trust in a known binary. A hijack can happen through several path and order mistakes; sideloading specifically relies on a nearby malicious DLL being found before the intended one.
That distinction matters to defenders because a sideloading event may preserve the appearance of normal execution more easily than a blunt path-abuse case. The executable may be legitimate, which means file reputation, allowlists, and process trust signals can look cleaner than the actual loading chain deserves. For context on how non-human or machine-oriented trust paths become risky when objects are over-privileged or poorly governed, see Ultimate Guide to NHIs and the related overview of Non-Human Identities.
What defenders should look for
For both techniques, the key question is whether a process is loading a library from a location that should not outrank the vendor or application directory. That includes writable application folders, user-writable locations, or directories that were not intended to host code. The difference is that DLL sideloading usually gives you a more believable host process, so you need to examine the full load chain, not only the executable name.
Good detection work focuses on library provenance and execution context. Look for unusual parent-child process relationships, DLLs loaded from non-standard paths, mismatches between a binary's signer and the DLL's origin, and repeated library loads immediately after software starts. If you are validating whether the loading behavior is a known hardening gap or a supply-chain style trust issue, the relevant control discussion overlaps with software integrity and load-path hygiene, which is why practitioners often pair this topic with SLSA and OWASP Cheat Sheet Series guidance on secure implementation practices.
In environments that rely on strong endpoint controls, the distinction also affects triage. A hijacking alert may indicate a broader configuration weakness, while sideloading often signals a more deliberate abuse of trust in an otherwise legitimate application. That makes the second case especially relevant for hunting, because the malicious DLL can be easy to miss if responders only whitelist the executable.
Risk and Threat Considerations
Both techniques can lead to code execution in a trusted process, which raises the stakes beyond a simple file-placement issue. The main risk is that attackers can blend malicious code into normal application startup, weaken attribution, and bypass controls that focus too narrowly on signed executables rather than the libraries they load.
Failure mechanism: An application resolves a DLL from an attacker-influenced location or search order, then executes the loaded code inside a trusted process context.
Impact: The attacker gains execution, persistence, or lateral movement opportunities while hiding behind a legitimate binary, and defenders may miss the compromise if they do not inspect library provenance.
Standards & Framework Alignment
This section maps relevant standards and security frameworks to the operational risks and controls described in this guidance.
MITRE ATT&CK address the attack and risk surface, while CIS Controls v8 set the governance and control requirements practitioners need to meet.
| Framework | Control / Reference | Relevance |
|---|---|---|
| MITRE ATT&CK | T1574.001 — DLL Search Order Hijacking | Directly covers abusing DLL load order to run attacker code in a trusted process. |
| T1574.002 — DLL Side-Loading | Directly matches the trusted-executable plus malicious-DLL abuse pattern described here. | |
| Recommendation — Hunt for DLLs loaded from unexpected paths and harden search order to block hijacking. Validate library provenance and flag trusted binaries that load unexpected DLLs from nearby locations. | ||
| CIS Controls v8 | 8.2 — Audit Log Management | Useful for detecting suspicious process and module-loading activity tied to DLL abuse. |
| 4.1 — Establish and Maintain a Secure Configuration Process | Applies because DLL abuse often exploits unsafe path and configuration choices. | |
| 2.4 — Address Unauthorized Software | Relevant when sideloading uses a legitimate host binary to introduce unauthorized code. | |
| Recommendation — Centralize and review module-load telemetry to spot anomalous DLL execution paths. Harden application directories and remove writable search paths that can be abused for DLL loading. Block or investigate unexpected binaries and adjacent DLLs in approved software locations. | ||
Practitioner Guidance
What to verify: Confirm which DLL path the process actually resolved at runtime, not just which executable launched. If the library came from a writable or user-controlled directory, treat it as a higher-confidence abuse case even if the host binary is legitimate.
Common mistake: Teams often hunt only for unsigned executables or obvious malware names. That misses the core issue here, which is trusted process abuse through library loading. Review application folders, load order behavior, and any software that routinely starts with elevated trust.
Practitioner takeaway: The operational distinction is that hijacking describes the load-order weakness, while sideloading is the more deceptive execution pattern, so detection and hardening must focus on where the DLL came from, not only on which program ran.
Related resources from NHI Mgmt Group
- What is the difference between fixing DLL hijacking in the application and blocking it at the endpoint?
- What is the difference between credential theft and session hijacking?
- What is the difference between session hijacking and credential theft?
- What is the difference between prompt injection and LLM hijacking in security operations?
Deepen Your Knowledge
Reviewed and updated by the NHIMG editorial team on September 18, 2026.
NHI Mgmt Group — the #1 independent authority on Non-Human Identity, IAM, and Agentic AI security. nhimg.org
