Malicious PDF — malware analysis report

Static analysis result for SHA-256 3873cef8b962dc3b…

MALICIOUS

PDF

70.6 KB Created: 2021-10-06 19:11:48 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-11-24
MD5: 9b7e109cef8fb088b5828260161abb4a SHA-1: 15b2970efc5cb4747266ec32431764f3fb28b888 SHA-256: 3873cef8b962dc3b1e7b9bd839ea40fbc305a2be9f21d3de0e83aaee8b5fc851
126 Risk Score

Malware Insights

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

The PDF file was flagged by multiple heuristics, including a high-confidence ML classifier and ClamAV detection, indicating malicious intent. The PDF_SEO_DISPOSABLE_LINK_FARM heuristic specifically points to the document acting as a link farm, directing users to numerous distinct hosts, likely for phishing or malware distribution. No scripts were extracted, and the document body was unreadable, but the presence of many embedded URLs and the link farm heuristic strongly suggest a social engineering attack.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9982

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://geoman.cz/data/file/94946951024.pdf In PDF document text
    • http://velapower.com/glwh/UploadFile/file/2021092409052273499.pdfIn PDF document text
    • http://www.jhannahs.com/wp-content/plugins/formcraft/file-upload/server/content/files/16137e63619f62---kaluruwedo.pdfIn PDF document text
    • https://tekstilkentrehber.com/upload/ckfinder/files/reviderubunatorosa.pdfIn PDF document text
    • http://avemkz.internet-match.com/upload/files/pugepeponerawuleki.pdfIn PDF document text
    • http://giasudaihocsupham.com/Images_upload/files/85787477197.pdfIn PDF document text
    • https://aspirans.com/files/file/zonujazupenep.pdfIn PDF document text
    • http://laxycoffee.com/upload/files/lirojew.pdfIn PDF document text
    • http://motolargo.pl/userfiles/file/93414039488.pdfIn PDF document text
    • http://kpdb.org/userfiles/files/rifoxugare.pdfIn PDF document text
    • https://rayvoltbike.tw/geektic/files/wutorariresaledurumul.pdfIn PDF document text
    • https://ku4ysk-9lgp4y.com/contents/files/50432257160.pdfIn PDF document text
    • http://www.vljainandco.com/userfiles/files/47397775518.pdfIn PDF document text
    • http://oldmotorsclub.com/files/file/nutikuladiginagepelo.pdfIn PDF document text
    • http://akicgiyim.com/userfiles/file/lufopi.pdfIn PDF document text
    • https://bda.ch/ckfinder/userfiles/files/13007144331.pdfIn PDF document text
    • https://niboparis.com/upload/fckeditor/files/14419291355.pdfIn PDF document text
    • https://ensegun2.com/ckfinder/userfiles/files/73353941168.pdfIn PDF document text
    • http://patrickstaxi.fr/userfiles/file/77307424393.pdfIn PDF document text
    • http://niestachow.pl/data/aktualnosci_imgs/file/63874061783.pdfIn PDF document text
    • https://arbormaster.us/uploads/files/66599973020.pdfIn PDF document text
    • http://maksimetall.ru/files/45723527001.pdfIn PDF document text
    • https://feedproxy.google.com/~r/Uplcv/~3/YTWXjIUwRh0/uplcv?utm_term=ford+audio+system+manualPDF 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_off0000b43f.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xB43F 10600 bytes
SHA-256: 2e181c20050f82907dc9094d93515ded8f0e245647ad79a156f1f44ffac2c8b0
font_01_sfnt_off0000cc72.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xCC72 15744 bytes
SHA-256: 7d0fb35b1a65b5707e1657b2fbf3d4c3423f1f7a95bbb522aeb23a0b16c4940f
font_02_sfnt_off0000f4b3.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xF4B3 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1