Malicious PDF — malware analysis report

Static analysis result for SHA-256 a81af14d75e66aa3…

MALICIOUS

PDF

81.0 KB Created: 2021-05-20 01:30:14 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 4.8.7)
MD5: 5eaf3fe0d2d23e4f1c47aa6f65cd2e62 SHA-1: 7e9f17bb7aeade16c0e2cefbd44584668baa10dc SHA-256: a81af14d75e66aa31236056a553900a6943bb2ed1b5e49a8902964309e2200a5
186 Risk Score

Malware Insights

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

This PDF file is identified as malicious by ClamAV and an ML classifier. It contains a large number of external links, many of which point to disposable hosting services, suggesting a link farm or phishing attempt. The primary malicious URL identified is https://jacksth.ru/strik, which is likely used to redirect users to further malicious content. No scripts were extracted from this sample.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9997

Heuristics 6

  • Small PDF contains mass external PDF link farm critical PDF_SEO_LINK_FARM
    Small PDF contains many clickable external PDF links, mostly clustered on one host. This matches generated SEO/link-farm PDF carriers used to route users into malicious or unwanted-software delivery chains, rather than a normal document citation pattern.
  • 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://jacksth.ru/strik?utm_term=manual+de+kinesiologia+aplicada+pdf
    • https://cdn-cms.f-static.net/uploads/4391620/normal_6056d065900ce.pdf
    • https://cdn-cms.f-static.net/uploads/4473919/normal_603efdbf0e2fc.pdf
    • https://ferijivoko.weebly.com/uploads/1/3/5/3/135327637/33752b6d32c.pdf
    • https://zorisurirumu.weebly.com/uploads/1/3/4/6/134600588/7107438.pdf
    • https://static.s123-cdn-static.com/uploads/4413469/normal_5fce98fc90784.pdf
    • https://larojebuwovu.weebly.com/uploads/1/3/1/3/131382373/kaguk_zoduxadafejo_kozutukeb_zupevabujozi.pdf
    • https://xaweworamek.weebly.com/uploads/1/3/4/6/134610398/9d9288ddb.pdf
    • https://nowesepi.weebly.com/uploads/1/3/1/1/131164229/5916933.pdf
    • https://tawisowa.weebly.com/uploads/1/3/5/3/135315305/5822676.pdf
    • https://dagigofeno.weebly.com/uploads/1/3/4/8/134887245/8948751.pdf
    • https://cdn-cms.f-static.net/uploads/4495558/normal_60698cfca4a7c.pdf
    • https://kuwuxegizeduki.weebly.com/uploads/1/3/2/6/132695805/7441049.pdf
    • https://wuwexolajux.weebly.com/uploads/1/3/0/8/130814226/donoxawasitif.pdf
    • https://cdn-cms.f-static.net/uploads/4381541/normal_60329cb784e75.pdf
    • https://gerugufudob.weebly.com/uploads/1/3/4/8/134869234/6651757.pdf
    • https://lurenosofen.weebly.com/uploads/1/3/0/7/130740325/diguto.pdf
    • http://www.ascendercorp.com/
    • http://www.ascendercorp.com/typedesigners.html
    • https://uploads.strikinglycdn.com/files/922fd3be-8c1b-4796-b29d-df643313eb34/89298316904.pdf
    • https://uploads.strikinglycdn.com/files/0a9307cc-5fd5-442a-a219-9030aa4b23a2/tugukovaluvepexixozuduw.pdf
    • https://s3.amazonaws.com/sesijesule/98050996449.pdf
    • https://s3.amazonaws.com/sivanira/depazaju.pdf
    • https://s3.amazonaws.com/desenaz/71739880613.pdf
    • http://www.w3.org/1999/02/22-rdf-syntax-ns#
    • http://purl.org/dc/elements/1.1/
    • http://ns.adobe.com/pdf/1.3/
    • http://ns.adobe.com/xap/1.0/
    • http://ns.adobe.com/xap/1.0/mm/
    • http://ns.adobe.com/xap/1.0/rights/
    • http://scripts.sil.org/OFL

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
font_00_sfnt_off0000fa82.bin
54f682dcd352c77ab410e55bdf3629f827c8fd8aeb2af0825e86a9150fb72eea		 pdf-font-stream PDF embedded font (sfnt) at offset 0xFA82 5296 bytes
font_01_sfnt_off00010cb2.bin
5711ec858ab4889a2d0f1c0d959050b1d1541a7d31f18db97baedf525bec868b		 pdf-font-stream PDF embedded font (sfnt) at offset 0x10CB2 14084 bytes

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