Malicious PDF — malware analysis report

Static analysis result for SHA-256 81a9c5a30ea7b7e3…

MALICIOUS

PDF

84.2 KB Created: 2021-06-06 05:54:50 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 4.8.7) First seen: 2021-11-24
MD5: 03e504ddd435418d6e0fe392f804c119 SHA-1: eb320e3a4dd36e253adeab6d4577aafb2f80e949 SHA-256: 81a9c5a30ea7b7e3b211f1b0a66ec17607c99b07739d40f961708517e99a272d
126 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1059.007 JavaScript

The PDF file was flagged as malicious by ML classifiers and ClamAV, indicating a high likelihood of malicious intent. It contains numerous embedded URLs, with one specifically pointing to a link farm designed for disposable hosting, suggesting a phishing or malware distribution scheme. The document body, though heavily obfuscated, contains metadata related to 'wkhtmltopdf' and a date, but lacks clear instructional text, reinforcing the reliance on external links for the attack.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9998

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 https://cructi.ru/pbw?utm_term=collections+close+reader+student+edition+grade+7+pdf PDF link annotation
    • https://static.s123-cdn-static.com/uploads/4426571/normal_5fe1592e18520.pdfIn PDF document text
    • https://xixurisegiwawaz.weebly.com/uploads/1/3/4/0/134012782/jijutidoribimi.pdfIn PDF document text
    • https://pujuxapalijened.weebly.com/uploads/1/3/6/0/136009243/tuwisuxavovegu.pdfIn PDF document text
    • https://sozivaxuzafuzi.weebly.com/uploads/1/3/1/8/131856435/1983219.pdfIn PDF document text
    • https://xudixakutax.weebly.com/uploads/1/3/0/7/130776611/sirugowof-kenoginaxat-gubadenijobiwa-kananutowa.pdfIn PDF document text
    • https://static.s123-cdn-static.com/uploads/4454544/normal_5fced27a643a6.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4416504/normal_602c160c42097.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4447630/normal_60129f46dd858.pdfIn PDF document text
    • http://www.ascendercorp.com/In PDF document text
    • http://www.ascendercorp.com/typedesigners.htmlIn PDF document text
    • https://uploads.strikinglycdn.com/files/66c11b75-b020-4854-bf0b-88a7f3b38ef8/44562706143.pdfIn PDF document text
    • https://uploads.strikinglycdn.com/files/1ed2d230-78c6-459b-86e2-cdf20b08af82/toro_gas_trimmer_carb.pdfIn PDF document text
    • http://dujimowiwup.pbworks.com/w/file/fetch/144694131/manuale_duso_frigorifero_whirlpool_sesto_senso.pdfIn PDF document text
    • http://sejuworepow.pbworks.com/w/file/fetch/144419013/54771498722.pdfIn PDF document text
    • http://sijomirurefi.pbworks.com/f/exercises_on_adjectives_for_class_3.pdfIn PDF document text
    • https://uploads.strikinglycdn.com/files/1f4309bd-38e0-4eb7-b616-a017d93a41f2/phrasal_verbs_meaning_in_tamil.pdfIn PDF document text
    • https://uploads.strikinglycdn.com/files/8739fb42-a664-4488-8a53-716fec6a9285/50061448962.pdfIn PDF document text
    • 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://scripts.sil.org/OFLIn PDF document text

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
font_00_sfnt_off000108ec.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x108EC 5308 bytes
SHA-256: a52226f71658d12dcf7493afacb856e61bcc601e7b0f2e3006b151ed6976db5b
font_01_sfnt_off00011b11.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x11B11 11808 bytes
SHA-256: ffd0fd274c76f83fe529b98a5795c17c6c1359d53bf5c77bfa2a65c773ce4ffe

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