Malicious PDF — malware analysis report

Static analysis result for SHA-256 a91306071bae2c1b…

MALICIOUS

PDF

73.7 KB Created: 2021-10-01 15:15:23 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-11-25
MD5: 7b3df6762d162bad3d6dce46dc8d4d2b SHA-1: 8086436763ce7d6e0efd5a1e9595fa68a74fa722 SHA-256: a91306071bae2c1b271f1b41a124e4a8551f296586bc198ecc1e8f950871575c
116 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1203 Exploitation for Client Execution

The PDF contains numerous embedded URLs that point to other PDF files hosted on various domains, many of which appear to be compromised or disposable. The ML classifier strongly indicated maliciousness, and the link farm heuristic suggests a tactic to distribute further content or manipulate search engine results. No scripts were extracted, limiting the analysis of direct execution vectors.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9973

Heuristics 6

  • PDF link farm points to compromised-WordPress upload storage medium PDF_COMPROMISED_CMS_UPLOAD_LINK_FARM
    PDF contains multiple clickable links, across many distinct hosts, whose targets are random-slug files parked in the upload directories of vulnerable WordPress form plugins (FormCraft, Super Forms). This is the hallmark of the 'free document/template' SEO phishing PDF family, which ranks for search queries and routes users into payload/redirect chains hosted on compromised sites. The PDF itself carries no exploit — the risk is the linked destinations.
  • 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.
  • QR-code redirect lure medium SE_QR_LURE
    Document instructs the user to scan a QR code with a phone — consistent with QR phishing, but also common in legitimate documents
  • 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 http://massintech.ru/img/outer/files/20869048224.pdf In PDF document text
    • http://sushiosushi.com/uploads/files/povetaw.pdfIn PDF document text
    • http://laibros.com/ckeditor/userfiles/files/petakotivinenilig.pdfIn PDF document text
    • http://www.mearesandassociatesllc.com/siteuploads/editorimg/file/vuxenabobuwuputa.pdfIn PDF document text
    • http://dichvuhieuchuan.com/upload/files/manupuzalivomomewi.pdfIn PDF document text
    • https://www.hs-hofgastein.salzburg.at/ckfinder/userfiles/files/wevosara.pdfIn PDF document text
    • http://www.1000ena.com/wp-content/plugins/formcraft/file-upload/server/content/files/16148b1821fef5---32941174768.pdfIn PDF document text
    • http://dpholding.ru/uploads/files/kadaxorepumilupur.pdfIn PDF document text
    • http://lifecontinues.ru/images/files/zofiwazowodajupewafepazek.pdfIn PDF document text
    • http://lexprikson.com/admin/style/images/userfiles/file/finobite.pdfIn PDF document text
    • http://rbtyutj01.com/userfiles/files/modinaluwakujofuk.pdfIn PDF document text
    • https://churchosonline.com/wp-content/plugins/super-forms/uploads/php/files/25fef89155fc71fb9c5225cd3b566cc7/14432455836.pdfIn PDF document text
    • http://discarga.com/wp-content/plugins/formcraft/file-upload/server/content/files/161352303aacc4---9642238408.pdfIn PDF document text
    • http://tanphatinst.com/vietkiendo/upload/file/giregoguxefekusuzi.pdfIn PDF document text
    • http://chamdure.com/DATA/files/rekajojuwosejuxe.pdfIn PDF document text
    • https://growyourmoney.in/userfiles/files/bodujipodexuxexezewugen.pdfIn PDF document text
    • http://klasykarozrywki.pl/public/images/fck/file/vaxonefolumibalavep.pdfIn PDF document text
    • http://dalnoboy.net/data/filestorage/upload/files/nifelorokotatevixek.pdfIn PDF document text
    • https://llbyggodesign.se/UserFiles/files/kupodomiwudititafuxaziso.pdfIn PDF document text
    • https://infotechloyalty.com/bot/ckfinder/uf/files/defitek.pdfIn PDF document text
    • http://www.kevinbrooks.ca/wp-content/plugins/formcraft/file-upload/server/content/files/16147565462a4d---worob.pdfIn PDF document text
    • http://finalbrand.cz/upload/file/47928479943.pdfIn PDF document text
    • http://eiffelflowersquesnel.com/userfiles/file/lomudukumiwi.pdfIn PDF document text
    • http://mstreatmentadvances.com/userfiles/files/59635477294.pdfIn PDF document text
    • https://feedproxy.google.com/~r/skout/mBVl/~3/S30rS-6n6vg/uplcv?utm_term=adobe+after+effect+cc+2015+full+crackPDF link annotation
    • 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_off0000b5b1.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xB5B1 10844 bytes
SHA-256: b4f780108a56620b5a40e2ba9140c3552806e721dce488307d67454673749653
font_01_sfnt_off0000cf0a.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xCF0A 19132 bytes
SHA-256: bd60acd2befd6f98bbb76e9b1c497576fd67b2509e5fe101125932f8c54c3cdf
font_02_sfnt_off000100db.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x100DB 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1

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