Malicious PDF — malware analysis report

Static analysis result for SHA-256 81613a226e3a16fd…

MALICIOUS

PDF

90.9 KB Created: 2021-09-02 15:47:37 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-10-05
MD5: b3b5447e1977a384697b7a9ab26ffd4c SHA-1: 595eaf92ac8f2a83bf71498dc426759ce523050a SHA-256: 81613a226e3a16fd42786e3a66f42e25da95427618af547c78c5a638a1d1801a
156 Risk Score

Malware Insights

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

The PDF contains numerous links pointing to other PDF files hosted on various domains, many of which are identified as compromised CMS uploads or disposable hosting. The ClamAV detection and ML classifier strongly indicate malicious intent, likely related to phishing or malware delivery through these linked documents. No scripts were extracted, and the document body was unreadable, so the attack pattern is inferred from the link farm structure and heuristic findings.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9973

Heuristics 6

  • ClamAV: Pdf.Phishing.Trojan-d2528dad23a95d95-d2528dad23a95d95-10044376-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Phishing.Trojan-d2528dad23a95d95-d2528dad23a95d95-10044376-0
  • 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.
  • 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://yogo110.com/userfiles/file/dosaloledasevokofuwigefa.pdf In PDF document text
    • http://boulderdivorcelaw.com/wp-content/plugins/formcraft/file-upload/server/content/files/160aa3478a1d78---vavixowikenarobako.pdfIn PDF document text
    • http://sklepjola.pl/userfiles/file/11310110479.pdfIn PDF document text
    • https://www.corridar.com/wp-content/plugins/super-forms/uploads/php/files/uecs878mafitim6oh0umgm6qbf/92515444302.pdfIn PDF document text
    • http://bergfin.se/wp-content/plugins/formcraft/file-upload/server/content/files/16082804078dc9---paboli.pdfIn PDF document text
    • http://pantryscan.com/123cars/imagefck/file/68002137092.pdfIn PDF document text
    • https://wcdt.co.th/wp-content/plugins/super-forms/uploads/php/files/ghkmrvsfn3sbclu1daj2a8iph3/44967781187.pdfIn PDF document text
    • https://digireg.dk/upload/25494825269.pdfIn PDF document text
    • https://useoneconvo.com/wp-content/plugins/super-forms/uploads/php/files/652e41fba31cd6e7b6e22ae847fa120c/40581749631.pdfIn PDF document text
    • https://mimpi1pusat.com/contents//files/8554986957.pdfIn PDF document text
    • https://brukspec.pl/upload/file/barufif.pdfIn PDF document text
    • https://www.teppiche-waschen-hamburg.de/wp-content/plugins/formcraft/file-upload/server/content/files/16094d399644b2---7388710828.pdfIn PDF document text
    • http://langmypham.com/luutru/files/tugirijava.pdfIn PDF document text
    • https://iveducentar.com/uploads/assets/file/68681725081.pdfIn PDF document text
    • https://www.hontoys.com.au/wp-content/plugins/super-forms/uploads/php/files/81019sg0cspn4e2emukb554j43/57400734925.pdfIn PDF document text
    • https://rclurie.com/wp-content/plugins/super-forms/uploads/php/files/6b1f8e894e81d668517a5e188c2bd617/budekobopujivogalasege.pdfIn PDF document text
    • http://studiodabo.eu/userfiles/files/34758401994.pdfIn PDF document text
    • http://laulumaja.fi/ckfinder/userfiles/files/79860311888.pdfIn PDF document text
    • http://grani-tonkogo-mira.ru/wp-content/plugins/super-forms/uploads/php/files/fe103c4c905beddfdb9b6caa6cd1a884/bitetanidimelanimekudejiz.pdfIn PDF document text
    • http://crystalnymph.by/wp-content/plugins/super-forms/uploads/php/files/afa260d4e0453705c04395e5218bf72b/vedosixurev.pdfIn PDF document text
    • http://cargo3030.ru/wp-content/plugins/formcraft/file-upload/server/content/files/1611aeb5868629---10654211448.pdfIn PDF document text
    • https://carthink.org/wp-content/plugins/formcraft/file-upload/server/content/files/16083f3043bf8c---fivefuloxoduzekirujup.pdfIn PDF document text
    • https://www.d-table.com/wp-content/plugins/super-forms/uploads/php/files/4a5ff3fb9529bbf9e500651b7a0c66f4/wirowaduxomadutigage.pdfIn PDF document text
    • https://equantumconsulting.com/files/files/99247144177.pdfIn PDF document text
    • https://seataclightingalaska.com/wp-content/plugins/super-forms/uploads/php/files/1fdf86ddbe1fa61397860345f5e37280/75201491596.pdfIn PDF document text
    • https://feedproxy.google.com/~r/Uplcv/~3/BkSY9tpko7c/uplcv?utm_term=software+engineering+pdf+notesPDF 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_off0000fd90.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xFD90 18588 bytes
SHA-256: 819f46b168c9b38d2b3d4fd40a51a063962965117a42b0bdd5b9e0fbd960065b
font_01_sfnt_off00012cec.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x12CEC 10788 bytes
SHA-256: 650dfa1067ef3f46ce319eb0412d30369fc20c40639460803177fa0bc2ed2ab6
font_02_sfnt_off000145c4.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x145C4 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1