Malicious PDF — malware analysis report

Static analysis result for SHA-256 251284616dfa8a81…

MALICIOUS

PDF

82.2 KB Created: 2021-10-10 00:08:43 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3)
MD5: 56c83e88cf0f635a4346ce95569c317f SHA-1: d6d1f2a7d21369066a7499fed33419654904da4a SHA-256: 251284616dfa8a810b6e53136e88171231ebf2e09c0b6aba950df0fa11401fdd
156 Risk Score

Malware Insights

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

The sample is identified as malicious by ML classifiers and ClamAV, indicating a high likelihood of malicious intent. It contains numerous external URLs, many pointing to compromised CMS uploads or disposable hosting, suggesting a link farm designed to redirect users. The presence of PDF-specific heuristics like PDF_URI and PDF_SEO_DISPOSABLE_LINK_FARM further supports this, indicating the document's primary function is to lead users to external, potentially malicious, content.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9990

Heuristics 6

  • ClamAV: Pdf.Phishing.Trojan-d2568dad23a94d95-d2568dad23a94d95-10044375-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Phishing.Trojan-d2568dad23a94d95-d2568dad23a94d95-10044375-0
  • 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 https://smidgel.ru/uplcv?utm_term=make+the+most+of+your+day+quotes
    • https://creativenursery.net/home/creative/public_html/ckfinder/userfiles/files/xetenutipuxalupewavoxes.pdf
    • https://www.web2business.pt/wp-content/plugins/formcraft/file-upload/server/content/files/1615f7ffd6856b---55343817829.pdf
    • https://mycultureis.com/FileData/ckfinder/files/20210929_376B9E4386BB7DFF.pdf
    • http://asr-net.ru/uploads/files/89932494111.pdf
    • https://hankilfood.com/upfile/files/rojajumodufafoduvej.pdf
    • http://hoitruyengiaocodocvietnam.com/uploads/image/files/51737517039.pdf
    • https://rjiminfra.com/wp-content/plugins/super-forms/uploads/php/files/f3f4f822b322f45ebff141e10a718b83/70989477904.pdf
    • http://gurmanosypsnys.lt/userfiles/file/89098682555.pdf
    • http://lorofilmes.com/Uploads/ckfinder/userfiles/files/pubuwazuxafo.pdf
    • http://investin-khj.ir/ckfinder/userfiles/files/zamedekukizanagakuge.pdf
    • https://123kozijnofferte.nl/wp-content/plugins/super-forms/uploads/php/files/524c23a5a3e8cd5971bda6f82a1b417f/dagakidaluliduruvaxapo.pdf
    • https://namdolove.com/FileData/ckfinder/files/20210929_FC6C83C4EE7C9E75.pdf
    • https://ispartaprefabrik.com/ckfinder/upload/files/libilajipov.pdf
    • http://archive-2014.humandoc.pl/attachments/file/jipusujavolemevunasa.pdf
    • http://bakefruit.com/uploads/files/202109031655442294.pdf
    • http://www.alwaysflorida.com/wp-content/plugins/formcraft/file-upload/server/content/files/16143c9b2edb3b---13146258095.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://dejavu.sourceforge.net
    • http://dejavu.sourceforge.net/wiki/index.php/License

Extracted artifacts 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
font_00_sfnt_off0000d945.bin
c03d6375550cb745a0c9b261574a8332ac60ee1b6f7271e85e115dcc04189c93		 pdf-font-stream PDF embedded font (sfnt) at offset 0xD945 19068 bytes
font_01_sfnt_off00010a99.bin
28c2a5cafe727f8e0e64922df3a9b937c7b377de4dcf14f9f801880db239fb4f		 pdf-font-stream PDF embedded font (sfnt) at offset 0x10A99 10820 bytes
font_02_sfnt_off00012370.bin
9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1		 pdf-font-stream PDF embedded font (sfnt) at offset 0x12370 16792 bytes

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