zlib1.dll threat report

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• Overview
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Analyst brief

What this report says

GridinSoft Anti-Malware detects zlib1.dll as PUP.SystemOptimizer. The sample was last observed on 2025-03-16 23:01:38 (a year ago) / zlib.

This page combines the detection verdict with file identity, publisher metadata, alternate names, observed paths, geography, OS signals, and PE details so the report reads as a triage record rather than a standalone download page.

GridinSoft Anti-Malware detection

Detected by GridinSoft before you download

The current ThreatInfo record shows this exact file hash detected as PUP.SystemOptimizer. Download GridinSoft Anti-Malware to scan the device, confirm whether this file is present, and remove the detected object if it is found.

Detection name

PUP.SystemOptimizer

Recommended action

Scan and remove

Last analysis

2025-03-16 23:01:38 (a year ago)

File hash

c126d5728f3e6de03fc83c82f0cfb5bf

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Why it matters

Why GridinSoft flags this file

Detection

GridinSoft identifies the sample as PUP.SystemOptimizer.

Timeline

First seen 2025-03-16 23:01:38 (a year ago); latest analysis 2025-03-16 23:01:38 (a year ago).

Publisher context

Product metadata: zlib.

Digital signature

Signed by Qiwang Computer. The signature is reported as valid, but signed files can still be bundled or abused.

Observed locations

ThreatInfo has seen this file in user or system paths listed below. Unexpected locations increase the need for local verification.

Recommended action

What to do next

1. Compare the MD5 above with the file found on the device.
2. Check whether the file appears in the observed locations or under one of the alternate names.
3. Run GridinSoft Anti-Malware to confirm the detection and remove the file if it is present.

zlib1.dll is a Windows file recorded in the ThreatInfo database. It is associated with zlib. The current detection status is PUP.SystemOptimizer, based on the latest analysis from 2025-03-16 23:01:38 (a year ago).

If zlib1.dll appears on your computer unexpectedly, treat it as suspicious. Check its location, digital signature, and recent system changes before allowing it to run. A full anti-malware scan is recommended when this file is detected as PUP.SystemOptimizer.

File Details

The screenshot is a visual record of a GridinSoft Anti-Malware detection for this sample. Use the hash and metadata above as the primary identifiers when comparing the file on your system.

Overview

The signature on zlib1.dll is reported as valid. A valid signature helps confirm publisher identity, but it does not automatically make the file safe if the installer was bundled, abused, or downloaded from an untrusted source.

ThreatInfo has observed zlib1.dll in the locations listed above. Files found in temporary folders, user profile folders, startup locations, or unusual application directories should be reviewed more carefully than files installed under a known program directory.

The strongest geographic signal for this file is Greece with 100.0% of observed hits. Geographic distribution can help identify targeted campaigns, regional software bundles, or where a file is most commonly reported.

The most common operating system signal for zlib1.dll is Windows 10 with 100.0% of observed hits. If your system differs from the common profile, check whether the file was introduced by a specific installer, archive, or removable device.

Analysis

zlib1.dll is identified as pe for 32 systems. The subsystem is Windows GUI. PE header values are useful for triage, especially when they do not match the expected publisher, product, or release timeline.

PE section names and hashes can reveal packing, injected resources, or unusual build artifacts. Sections with uncommon names, very large raw data, or hashes that differ from a trusted copy deserve additional review.