Unsigned DLL Loaded by a Trusted Process

Last updated 9 days ago on 2025-05-05
Created 2 years ago on 2023-07-12

About

Identifies digitally signed (trusted) processes loading unsigned DLLs. Attackers may plant their payloads into the application folder and invoke the legitimate application to execute the payload, masking actions they perform under a legitimate, trusted, and potentially elevated system or software process.
Tags
Domain: EndpointOS: WindowsUse Case: Threat DetectionTactic: Defense EvasionRule Type: BBRData Source: Elastic DefendLanguage: eql
Severity
low
Risk Score
21
MITRE ATT&CK™

Defense Evasion (TA0005)(opens in a new tab or window)

License
Elastic License v2(opens in a new tab or window)

Definition

Rule Type
Event Correlation Rule
Integration Pack
Prebuilt Security Detection Rules
Index Patterns
logs-endpoint.events.library-*
Related Integrations

endpoint(opens in a new tab or window)

Query
library where host.os.type == "windows" and
   (dll.Ext.relative_file_creation_time <= 500 or
    dll.Ext.relative_file_name_modify_time <= 500 or
    dll.Ext.device.product_id : ("Virtual DVD-ROM", "Virtual Disk")) and dll.hash.sha256 != null and
    process.code_signature.status :"trusted" and not dll.code_signature.status : ("trusted", "errorExpired", "errorCode_endpoint*") and
    /* DLL loaded from the process.executable current directory */
    endswith~(substring(dll.path, 0, length(dll.path) - (length(dll.name) + 1)), substring(process.executable, 0, length(process.executable) - (length(process.name) + 1)))
    and not user.id : "S-1-5-18" and
    not dll.hash.sha256 : (
        "19588e6a318894abe8094374bee233e666f319de909c69f12a6047b14473e299",
        "6e8bee250c8cc1b65150522f33794759f5c65f58fff17c5cbf6422ad68b421d2",
        "55de11531dc0e566cb91f26e48d1301a161a4b8b24abed42304d711412368760",
        "56a5148d00c2d9e58415be2d64eca922a58063fe26d9af1c87084aa383c9058e",
        "83ee0ff920144edb2c2f4ea10130f55443493290886985a63233fa2431e450f9",
        "0d0d8f2eaff6b5f75e63d9721d5a0480b30e70792fe0d3a24d76fd3e61b05982",
        "8b6ce3a640e2d6f36b0001be2a1abb765ae51e62c314a15911e75138cbb544bb",
        "ea02a19dd824cb7d611b8821d1b9e6a076714a195d027d1ff918128a64ac5220",
        "02a6d001e6dd944738e09b720e49dcb1272cb782b870e5ae319d4600bc192225",
        "e7714a1d6ac3f4c4ae22564b9ca301e486f5f42691859c0a687246c47b5cf5c9",
        "17f0f709fb7f6190c03b19b6198fd863b6f0d79f46ccfebac6064be747a4cb3e",
        "cb7ab3788d10940df874acd97b1821bbb5ee4a91f3eec11982bb5bf7a3c96443",
        "c944ee510721a1d30d42227cc3061dfdcbc144c952381afcfe4f6e82c5435ffc",
        "967189adfbc889fde89aafc867f7a1f02731f8592cf6fd5a4ace1929213e2e13",
        "4a824526749790603eb66777f79787128dd282162a3904a4c1135de43b14d029",
        "620a7e658af05cc848091b8a639854b9b15700a9061b4a3d078523653133a4af",
        "cb220267fb0116b298bab6a09a764420d630c52026f7d750f8ffca4818389327",
        "0da1f856d92d6b95f10ed8c3f629cd15468c906de9352fb4ae629139d1412eed",
        "e1646c7778c24407a17881908037a49ecfcb5a980d155212d544302653a3ef62",
        "e102c9c5b22ceb60dc516ab4124bea8ec8e808b08eec48ea7ac674d13fca82ef",
        "c7544e1f9927afdf6e8cd7063020b572e60fe8f00af39227eb831d331df38225",
        "3668c6749db59a6cbc5293d0a4f904f76d6fb5048704449dd53894916f408a57",
        "7705851ba047a8154402aca92621b60be0e0e9d9b52b19bf8be540305bd53dba",
        "b5acf358ff97127eac9ef4c664a980b937376b5295ef23d77ee338225de10d60",
        "394d2d862f2ddce71f28d9b933b21a7d6c621c80ef28652574f758f77f01f716",
        "e958d03db79e9f1d2770c70a5bc24904aa3e2d27a8d5637684cf8166b38908f2",
        "284701380f33a30b25e8eb9822e7f47179238e91d08bd3fb5a117145de7e0d8d",
        "497471497886f18ca16f7facab7d76dc9bfadd69deb9c6e4ea9bdc0869a15628",
        "739bedcfc8eb860927eb2057474be5b39518aaaa6703f9f85307a432fa1f236e",
        "8f4c72e3c7de1ab5d894ec7813f65c5298ecafc183f31924b44a427433ffca42",
        "1ac4753056179b358132c55ca3086d550849ae30259ba94f334826c2fbf6c57e",
        "53e8fecd7d4b1b74064eba9bfa6a361d52929f440954931b4ba65615148bf0ea",
        "e9088afd8871dbad5eda47a9d8abf3b08dd2e17c423ba8a05f9b6ad6751f9b7c",
        "ab27eb05130db2f92499234b69ff97ee6429c7824efcb7324ae3e404e2b405bf",
        "553451008520a5f0110d84192cba40208fb001c27454f946e85e6fb2e6553292"
    )

Install detection rules in Elastic Security

Detect Unsigned DLL Loaded by a Trusted Process in the Elastic Security detection engine by installing this rule into your Elastic Stack.

To setup this rule, check out the installation guide for Prebuilt Security Detection Rules(opens in a new tab or window).