Windows DLL Sideloading: libcurl.dll Loaded by gup.exe from Uncommon Location

Alerts when gup.exe loads libcurl.dll from a path that doesn’t match the excluded Notepad++ GUP.exe location.

FreeReviewedSigma · Medium · v2

Product: windows
Category: image_load
Author: Nasreddine Bencherchali (Nextron Systems) (SigmaHQ), DRL 1.1
Published: 2023-05-05
Updated: 2026-07-31

ATT&CK techniques

Execution → Defense Evasion

Recon
Resource Dev
Initial Access
Execution
- T1574.001DLL
Persistence
- T1574.001DLL
Priv Esc
- T1574.001DLL
Defense Evasion
- T1574.001DLL
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule flags when the gup.exe process loads libcurl.dll, with the DLL located in an uncommon path. Attackers may use DLL sideloading to execute malicious code by hijacking how a legitimate executable resolves dependencies. The detection relies on Windows image load telemetry, matching the loaded module name and the loader process path ending with gup.exe, while excluding a known benign Notepad++ updater path.

Reporting behind it

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Windows DLL Sideloading: libcurl.dll Loaded by gup.exe from Uncommon Location

Pivot detection · T1574.001 · 9 related

Changelog

v2
Candidate ingested via manual entry.2026-07-31
v1
No changelog recorded for this version.2026-07-30

Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.

windows-dll-sideloading-gup-exe-loading-libcurl-dll-from-uncommon-path-e49b5745

title: "Windows DLL Sideloading: libcurl.dll Loaded by gup.exe from Uncommon Location"
id: 890a6c9d-1f95-4c04-9df2-7f1b1c48b65c
status: test
description: This rule flags when the gup.exe process loads libcurl.dll, with the DLL located in an uncommon path. Attackers may use DLL sideloading to execute malicious code by hijacking how a legitimate executable resolves dependencies. The detection relies on Windows image load telemetry, matching the loaded module name and the loader process path ending with gup.exe, while excluding a known benign Notepad++ updater path.
references:
  - https://labs.withsecure.com/publications/fin7-target-veeam-servers
  - https://github.com/SigmaHQ/sigma/blob/master/rules/windows/image_load/image_load_side_load_gup_libcurl.yml
author: Nasreddine Bencherchali (Nextron Systems), Huntrule Team
date: 2023-05-05
tags:
  - attack.persistence
  - attack.privilege-escalation
  - attack.execution
  - attack.stealth
  - attack.t1574.001
logsource:
  category: image_load
  product: windows
detection:
  selection:
    Image|endswith: \gup.exe
    ImageLoaded|endswith: \libcurl.dll
  filter_main_notepad_plusplus:
    Image|endswith: \Notepad++\updater\GUP.exe
  condition: selection and not 1 of filter_main_*
falsepositives:
  - Unknown
level: medium
license: DRL-1.1
related:
  - id: e49b5745-1064-4ac1-9a2e-f687bc2dd37e
    type: derived

Convert

This rule as a query you can run. Uses no unlock credit.

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