Malicious PDF — malware analysis report

Static analysis result for SHA-256 83d3ea8bf74d3fd1…

MALICIOUS

PDF

94.1 KB Created: 2021-06-25 08:28:17 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 4.8.7) First seen: 2021-10-27
MD5: 355d759e171724f05514be0e7f79bf34 SHA-1: 5f4c29fa40e330ee39224429c21e6c6740000e49 SHA-256: 83d3ea8bf74d3fd1fb2f252bc80a36af4365eb52e2faadc6092bd5aa87c94459
96 Risk Score

Malware Insights

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

The ML classifier strongly indicated maliciousness, and multiple heuristics identified the PDF as a link farm pointing to compromised CMS uploads and disposable hosting. The document body, though heavily obfuscated, contains metadata suggesting it was generated by wkhtmltopdf, and the presence of numerous external URLs indicates an attempt to redirect the user to potentially malicious content. The primary attack pattern involves luring users to external sites, likely for further exploitation or phishing.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9998

Heuristics 5

  • 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://aeskulap24h.com/wp-content/plugins/formcraft/file-upload/server/content/files/160b46a0acf851---rimaso.pdf In PDF document text
    • http://ck-tct.ru/userfiles/file/34310228386.pdfIn PDF document text
    • https://arch.ua/ckfinder/userfiles/files/91551076203.pdfIn PDF document text
    • http://braintradingbcn.com/wp-content/plugins/super-forms/uploads/php/files/c0b5416d9d8d15d8d1201e4ccbc25573/tuporixidijibi.pdfIn PDF document text
    • http://oticonshop.net/ckfinder/userfiles/files/wimomuwelo.pdfIn PDF document text
    • https://clap-bas.com/userfiles/file/witanalepulixaxogud.pdfIn PDF document text
    • http://csc025.com/userfiles/file/20210610092114_kmyur9.pdfIn PDF document text
    • http://dui-antidote.com/images/userfiles/file/kiwexizovelarerelujuzu.pdfIn PDF document text
    • https://genesislighting.net/wp-content/plugins/super-forms/uploads/php/files/86cfa5a4d4e43a524be9caade8732d86/xipapusimexawaxer.pdfIn PDF document text
    • https://glosunspa.com/wp-content/plugins/formcraft/file-upload/server/content/files/16073233c9de92---16398246946.pdfIn PDF document text
    • http://ampletrekking.com/userfiles/file/womarim.pdfIn PDF document text
    • http://aberdeeneyes.co.uk/wp-content/plugins/formcraft/file-upload/server/content/files/160956e75a2534---14299418509.pdfIn PDF document text
    • http://pho32shabu.com/uploads/files/68818616798.pdfIn PDF document text
    • https://dungcuruamui.com/wp-content/plugins/super-forms/uploads/php/files/7mh8ra53sauit61rlrsqo07d95/jifomuvizusufovusipe.pdfIn PDF document text
    • http://www.ascendercorp.com/In PDF document text
    • http://www.ascendercorp.com/typedesigners.htmlIn PDF document text
    • https://feedproxy.google.com/~r/skout/mBVl/~3/S30rS-6n6vg/uplcv?utm_term=mary+higgins+clark+pdfPDF 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://scripts.sil.org/OFLIn PDF document text

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
font_00_sfnt_off00012e02.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x12E02 5588 bytes
SHA-256: d49bb77ec85ea9629445432e9b380cf82a8c2e2472b72841c3c1533e79eb95dd
font_01_sfnt_off0001411a.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x1411A 12640 bytes
SHA-256: 8ec3ade107defb8e25f51293be02e184e5e3a0f3fcb4ea90a7ed579707d291cf

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