Malicious PDF — malware analysis report

Static analysis result for SHA-256 a4ecd20d9e75e8f0…

MALICIOUS

PDF

68.8 KB Created: 2021-10-03 12:10:31 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-11-24
MD5: bca33dc3da8224fbc12e79599bfa61cf SHA-1: 9b4948a9d868742ad7c2e979ef6155ec8bbca1dc SHA-256: a4ecd20d9e75e8f0aba77ca82ac5ebc37615c5be76d45ecac2f6db58e7a6a6dd
126 Risk Score

Malware Insights

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

The PDF was flagged by ClamAV as Pdf.Phishing.Trojan and by an ML classifier with high confidence. Heuristics indicate it functions as a link farm, containing numerous embedded URLs pointing to other PDF files, likely to obscure the final malicious destination. The presence of a 'utm_term_redirector' and a high number of distinct hosts suggest a phishing or malware distribution campaign.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9992

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://vietnam-intraco.com/webroot/img/files/19838234591.pdf In PDF document text
    • http://yaqeen-eg.com/userfiles/file/76456239134.pdfIn PDF document text
    • http://masterref.ru/editorfiles/file/pugebadobipuxalob.pdfIn PDF document text
    • http://nitexprofi.cz/userfiles/file/papemetofabujeso.pdfIn PDF document text
    • https://concurs-euclid.ro/upload/fck/lasuresesan.pdfIn PDF document text
    • http://roocenter.ru/upload/file/tamodolugu.pdfIn PDF document text
    • https://webtechnocrats.com/upload/file/18179865289.pdfIn PDF document text
    • http://jatyn.cn/upfiles/202109/file/1632297829.pdfIn PDF document text
    • http://studiopassarotti.it/userfiles/files/80421639571.pdfIn PDF document text
    • http://sushinamu.com/uploads/files/67309641290.pdfIn PDF document text
    • http://multiflex.ru/userfiles/file/75828580393.pdfIn PDF document text
    • http://studiorumeo.it/userfiles/files/vefazaxajumuseniripugas.pdfIn PDF document text
    • https://estidevelopers.com/wp-content/plugins/super-forms/uploads/php/files/8aa9d2561e2b44996d67d7d8ffb32a02/nonezaxu.pdfIn PDF document text
    • https://sangolongphuong.vn/longphuong/news/files/gusovazekaf.pdfIn PDF document text
    • https://mayphotocopydogia.com/upload/files/wusixukos.pdfIn PDF document text
    • https://phu-komplex.pl/pliki/file/kewutoni.pdfIn PDF document text
    • http://xn--365-pn7mwb654m2qn.com/ckupload/files/kumosewibi.pdfIn PDF document text
    • http://www.beverburcht.nl/upload/files/26162171424.pdfIn PDF document text
    • https://skinrepublic.vn/webroot/img/files/mopinewojifasosa.pdfIn PDF document text
    • https://odontologosmalca.com/images/userfiles/file/kowowifavided.pdfIn PDF document text
    • https://feedproxy.google.com/~r/Uplcv/~3/BkSY9tpko7c/uplcv?utm_term=staph+infection+in+sinusesPDF 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_off0000abd2.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xABD2 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1
font_01_sfnt_off0000c3e9.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xC3E9 10604 bytes
SHA-256: 77ec0339d469559f4cf3470006a5e8ff494f71f9e0f347495929bf7c01972c2b
font_02_sfnt_off0000dc15.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xDC15 16712 bytes
SHA-256: 40352cc10b660dc9a1a4eb6796f0a90c991bdf474b06d091810844731b921ed4

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