Malicious PDF — malware analysis report

Static analysis result for SHA-256 8c31115fd6257f09…

MALICIOUS

PDF

70.5 KB Created: 2021-09-28 09:09:22 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-11-02
MD5: 41e76b0a3861bcbda5f2d797875d82dc SHA-1: 7445271eb3726c4ea04a96409d72cb595d8b2a1c SHA-256: 8c31115fd6257f09432cef7474f461e4d4fa081aac7361f6c24a52cd090ac358
66 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment

The sample is a PDF file that contains numerous external links, many of which are embedded within the document's structure and appear to be part of a link farm. The ML classifier strongly indicates maliciousness. The presence of external URIs and the link farm heuristic suggest the primary goal is to redirect users to potentially malicious websites, likely for phishing or to download further malware.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9978

Heuristics 4

  • Small PDF is a non-clustered link farm on disposable hosting medium PDF_SEO_DISPOSABLE_LINK_FARM
    Small PDF contains many clickable external PDF links spread thin across many distinct hosts (no single dominant host), corroborated by a utm_term SEO-redirector link and/or links parked on free/disposable content hosts. This is the 'free document/template' SEO phishing PDF family, which ranks for search queries and routes users into payload/redirect chains, rather than a normal document citation pattern. The PDF itself carries no exploit — the risk is the linked destinations.
  • External URI info PDF_URI
    PDF contains an external URL action
  • Object number defined twice with different bodies info PDF_DUPLICATE_OBJ_BODY_INCREMENTAL
    The same indirect object (N G) is defined more than once with different body bytes. First-wins and last-wins readers will resolve different content, which is a parser-confusion shape used by targeted PDFs. Body-only differences are common in benign incremental updates, so severity is raised only when the duplicate carries active content.
  • Embedded URL info EMBEDDED_URL
    One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.
    URL https://infrive.ru/uplcv?utm_term=a+mind+for+numbers+barbara+oakley+pdf PDF link annotation
    • https://newoptic.sas-global.mn/uploads/files/tomodufawi.pdfIn PDF document text
    • http://rrarental.org/upload/file/sigutumus.pdfIn PDF document text
    • http://yao-cheng.com/uploadfiles/20210919202141.pdfIn PDF document text
    • https://highlander-inn.com/assets/userfiles/files/vokupaturato.pdfIn PDF document text
    • http://gardensyellowcab.com/admin/images/file/nudotiwemegitatoxoto.pdfIn PDF document text
    • http://hstairan.com/FCKeditor/editor/filemanager/connectors/php/userfiles/file/24519439723.pdfIn PDF document text
    • http://inphilong.com/upload/files/56273685528.pdfIn PDF document text
    • https://kuwaitpolyurethane.com/ckfinder/userfiles/files/pisebutugorof.pdfIn PDF document text
    • http://www.timtransportes.com/home/wp-content/plugins/formcraft/file-upload/server/content/files/161414ca09d458---nesedofiritufakudebinapa.pdfIn PDF document text
    • http://www.mezmat.ru/ckfinder/userfiles/files/30791452494.pdfIn PDF document text
    • http://hyunshin.net/userfiles/file/fababijivigowivamofage.pdfIn PDF document text
    • http://majedalkarkhi.com/pics/file/65917027145.pdfIn PDF document text
    • http://wefocusdesign.com/upload/files/mozoto.pdfIn PDF document text
    • http://seidels-mineralienwelt.de/images/uploaded/file/nufepujetagakasekamagar.pdfIn PDF document text
    • http://thaifilmind.com/UserFiles/file/jobajawegur.pdfIn PDF document text
    • https://www.horisunmauritius.com/wp-content/plugins/super-forms/uploads/php/files/3cc4d5b3fea9d158c21ff6ab002c217d/mezitarimaditiv.pdfIn PDF document text
    • http://cmtsport.com/pliki/luvipirudulu.pdfIn PDF document text
    • https://g4m3s-4p1-12s1.com/contents/files/66459166400.pdfIn PDF document text
    • http://cdjuchuan.com/upload/files/pobige.pdfIn PDF document text
    • http://erpos.sk/data/files/92786438571.pdfIn PDF document text
    • https://inverpalmas.com/aym_image/files/pajorifijoverevigo.pdfIn PDF document text
    • http://soskuwait.com/outscapes/admin/ckeditor/uploads/ck/files/17569528189.pdfIn PDF document text
    • http://johnmarzillier.com/ckfinder/userfiles/files/22842614272.pdfIn PDF document text
    • http://www.w3.org/1999/02/22-rdf-syntax-ns#In PDF document text
    • http://purl.org/dc/elements/1.1/In PDF document text
    • http://ns.adobe.com/pdf/1.3/In PDF document text
    • http://ns.adobe.com/xap/1.0/In PDF document text
    • http://ns.adobe.com/xap/1.0/mm/In PDF document text
    • http://ns.adobe.com/xap/1.0/rights/In PDF document text
    • http://dejavu.sourceforge.netIn PDF document text
    • http://dejavu.sourceforge.net/wiki/index.php/LicenseIn PDF document text

Extracted artifacts 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
font_00_sfnt_off0000b1e6.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xB1E6 16100 bytes
SHA-256: 85ad03a9c111a64fafe50c0b238bd91a905350c82b90781d9835e48afc9b47b2
font_01_sfnt_off0000dad7.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xDAD7 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1
font_02_sfnt_off0000f2ee.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xF2EE 10988 bytes
SHA-256: 822fda357c69f8fcb59528989d8a85c30cc4f629fe52c22b656890a9b38bab35

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