Malicious PDF — malware analysis report

Static analysis result for SHA-256 40b4d57d78975177…

MALICIOUS

PDF

73.6 KB Created: 2021-10-07 11:11:35 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-11-24
MD5: 450de5a6500a1f3272f09935c2bb4815 SHA-1: cc7ce163e1ebe6b3b86bb7db09443c5414adfd1c SHA-256: 40b4d57d78975177c707994cfd17c012d6aaf39294d90da683f41ae283720acc
126 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious Link

The sample is a PDF file flagged by ClamAV as Pdf.Phishing.Trojan and by an ML classifier as malicious. It contains numerous embedded URLs, many pointing to PDF files on various domains, suggesting a link farm or distribution network. One heuristic specifically identifies it as a link farm on disposable hosting, with a UTM term redirector, indicating a deceptive purpose.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9973

Heuristics 5

  • ClamAV: Pdf.Phishing.Trojan-d2568dad23a94d95-d2568dad23a94d95-10044375-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Phishing.Trojan-d2568dad23a94d95-d2568dad23a94d95-10044375-0
  • 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 http://dabaizhongxue.com/upload_fck/file/2021-9-6/20210906155717352019.pdf In PDF document text
    • http://astorandblack.net/emailer/userfiles/file/39795580365.pdfIn PDF document text
    • https://centar-znr-zop.hr/wp-content/plugins/formcraft/file-upload/server/content/files/16135bb5bdc26c---siwilevediwexuzusug.pdfIn PDF document text
    • https://arab-hams.com/Ups/files/98908766723.pdfIn PDF document text
    • http://gzlmjx.com/data/home/bxu2343160066/htdocs/uploadfile/files/zuvutuvabatinulujas.pdfIn PDF document text
    • http://geoodwierty.pl/files/file/999854167.pdfIn PDF document text
    • https://sterlingsez.com/ckfinder/userfiles/files/56391276036.pdfIn PDF document text
    • https://k-kompany.ru/wp-content/plugins/super-forms/uploads/php/files/6e74a83b20370494a1d7129189fe5834/32772670307.pdfIn PDF document text
    • https://sarenpinler.com/calisma2/files/uploads/70348072747.pdfIn PDF document text
    • http://hongshengfish.com/uploadfiles/2021090504081867224.pdfIn PDF document text
    • http://studiolegaletrotta.eu/userfiles/files/denenumamipafa.pdfIn PDF document text
    • http://cansuyu.org/resimler/files/63445991794.pdfIn PDF document text
    • http://vector-mebel.ru/uploads/files/defanetofagizopo.pdfIn PDF document text
    • http://highdeal.linkeo.net/ckfinder/userfiles/files/lilatuvozotekix.pdfIn PDF document text
    • http://shinies.ru/img/lib/file/zodukanugijerakititi.pdfIn PDF document text
    • http://happy-land.hu/editor_up/66302852095.pdfIn PDF document text
    • http://sweed-trans.eu/ckfinder/userfiles/files/kisutapogugutilo.pdfIn PDF document text
    • http://logicamail.it/draft/media/rajakike.pdfIn PDF document text
    • https://ckmusicdesign.nl/userfiles/file/21816561694.pdfIn PDF document text
    • http://sportingfoundation.com/uploads/file/22963449844.pdfIn PDF document text
    • http://demkapi.com/resimler/files/96277154547.pdfIn PDF document text
    • http://sport-zavora.cz/data/file/kubodifenonetebuj.pdfIn PDF document text
    • http://xn--dlek-5qa.com/admin/UserFiles/file/mevefosisoxujidakakifevi.pdfIn PDF document text
    • https://easresidence.ro/app/webroot/files/userfiles/files/toxobiwapujaxujelaf.pdfIn PDF document text
    • http://aksaaydinlatma.com/img/editor/image/file/kudete.pdfIn PDF document text
    • https://feedproxy.google.com/~r/1eyvgo/aqOO/~3/S30rS-6n6vg/uplcv?utm_term=dynamic+page+vs+static+pagePDF 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_off0000be80.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xBE80 16036 bytes
SHA-256: 8a43545065c6615ae1695f3353dd8dd1786a5c6747f9609633e2c616cdb023c6
font_01_sfnt_off0000e7fe.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xE7FE 10632 bytes
SHA-256: cec968218f00d3ad38199590d59cba94495c225479b6c1870b060113a729b609
font_02_sfnt_off00010067.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x10067 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1