Malicious PDF — malware analysis report

Static analysis result for SHA-256 833e3ccd138fb87c…

MALICIOUS

PDF

80.9 KB Created: 2021-09-14 06:21:49 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-10-16
MD5: 2391e13ab43089ce9e4f6b3ba8080067 SHA-1: 17a7ae0e06c04b9e72037fa051fdd9d018741adb SHA-256: 833e3ccd138fb87cf9d54f16ad4090b0bd4f6cd13fe35d159ebacac803654db1
156 Risk Score

Malware Insights

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

The PDF file was identified as malicious by ML classifiers and ClamAV, indicating a high likelihood of malicious intent. It functions as a link farm, with numerous URLs pointing to external sites, many of which are hosted on compromised or disposable domains. The presence of PDF_SEO_DISPOSABLE_LINK_FARM and PDF_COMPROMISED_CMS_UPLOAD_LINK_FARM heuristics further supports this, suggesting the document is used to distribute malicious content or phish users. No scripts were extracted, but the structure and URL patterns are indicative of a phishing or malware delivery attempt.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9968

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 https://dongytueduc.com/wp-content/plugins/super-forms/uploads/php/files/jtommra25a9ah2dlop02hdv7sc/99085345128.pdf In PDF document text
    • http://xinchenfast.com/upload/file/55015250205.pdfIn PDF document text
    • http://aquamedia.cn/ckfinder/userfiles/files/jufomadiputar.pdfIn PDF document text
    • http://taemyung.com/data/upload/file/semitaruxalovep.pdfIn PDF document text
    • http://thanhnienxp.com/vietkiendo/upload/file/jusabuwebaruzaba.pdfIn PDF document text
    • http://biancoacolori.it/userfiles/files/71928117939.pdfIn PDF document text
    • http://xn--b1adbbbaeqjtsflbfms0e.xn--p1ai/pict/file/23390979601.pdfIn PDF document text
    • http://aftckwt.com/uploads/file/duranaluzulujorog.pdfIn PDF document text
    • https://maydangson.com/vietkiendo/upload/file/fazed.pdfIn PDF document text
    • https://voziky-paletove.cz/mctree.cz/pictures/other/files/30209326553.pdfIn PDF document text
    • http://yongqingtech.com/d/files/kufalenovizevesak.pdfIn PDF document text
    • http://www.workbythai.com/admin/assets/images/biduda.pdfIn PDF document text
    • https://www.uflo.edu.ar/ckfinder/archivos/documentos/dabane.pdfIn PDF document text
    • http://ablerexthailand.com/userfiles/files/81334984161.pdfIn PDF document text
    • https://dcoderesearch.com/uploads/27772709002.pdfIn PDF document text
    • https://saraelv.no/wp-content/plugins/formcraft/file-upload/server/content/files/161337acdc08c6---42265446450.pdfIn PDF document text
    • http://debten.net/UserFiles/File/59047479526.pdfIn PDF document text
    • http://tongchangkj.com/uploadfile/file///2021091018025377.pdfIn PDF document text
    • http://oletrans.sk/editor_uploads/files/80323581356.pdfIn PDF document text
    • https://www.delaneyllc.com/ckfinder/userfiles/files/dolowejaxezolukabikuralu.pdfIn PDF document text
    • http://www.dr.schure.net/ckfinder/userfiles/files/riwukese.pdfIn PDF document text
    • https://insights3.com/wp-content/plugins/super-forms/uploads/php/files/1c9d2a539a1bec008cee70f972c5226a/14916017619.pdfIn PDF document text
    • https://feedproxy.google.com/~r/1eyvgo/aqOO/~3/GLLx1DTH0VQ/uplcv?utm_term=messenger+video+call+qualityPDF 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_off0000d615.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xD615 18204 bytes
SHA-256: 8c236d987835661eaa8aa547be122ecbb54abee1cf9c76e709671041350a567b
font_01_sfnt_off0001055a.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x1055A 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1
font_02_sfnt_off00011d71.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x11D71 10964 bytes
SHA-256: 72abb12f6cc71512125e7f47d1fd6d6973db1dd659ebfcb00daca46b143ac784

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