Malicious PDF — malware analysis report

Static analysis result for SHA-256 55ef3e39bb3c6b87…

MALICIOUS

PDF

88.8 KB Created: 2021-09-11 03:05:38 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-11-02
MD5: 9ea40f86d061b91b56fc2553011443fb SHA-1: db1605d37dffe618e6fd0a0253db9d85a6e0e0c8 SHA-256: 55ef3e39bb3c6b870945b2fcba07eba3bd275502efc7cc64aefd8aa827f53e2f
156 Risk Score

Malware Insights

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

The PDF contains numerous links, many pointing to compromised CMS upload storage and disposable hosting, indicative of a link farm used for phishing or malware distribution. The ML classifier and ClamAV detection strongly suggest malicious intent. The document body is heavily obfuscated and appears to be generated by wkhtmltopdf, not containing user-readable content, further supporting the interpretation of the PDF as a malicious container for external links.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9973

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 http://duhochoangthanh.com/upload/files/78885355062.pdf In PDF document text
    • http://bobhendrix-law.com/customer/3/d/9/3d947ad6ce2568d98b832ccf5548371bFile/vitalam.pdfIn PDF document text
    • https://faguaflowers.com/images/admin/file/zejoxupojematupuripexur.pdfIn PDF document text
    • https://kratky.eu/files/file/6815941106.pdfIn PDF document text
    • http://clear-es.net/yamituki-n/uploads/files/37727241150.pdfIn PDF document text
    • https://rarahil.org.np/ckfinder/userfiles/files/52579292197.pdfIn PDF document text
    • http://gardensyellowcab.com/admin/images/file/wajidebodevotes.pdfIn PDF document text
    • https://www.opsclown.it/ckfinder/userfiles/files/50107696085.pdfIn PDF document text
    • https://duhocblueocean.vn/ckfinder/userfiles/files/luxobepivawaz.pdfIn PDF document text
    • http://www.sospapa24.com/lib/ckfinder/imgupload/files/1982020227.pdfIn PDF document text
    • https://senegal4d.com/contents/files/24724546211.pdfIn PDF document text
    • http://nnk.gr/wp-content/plugins/formcraft/file-upload/server/content/files/1613527f267567---mewekozudivuluzol.pdfIn PDF document text
    • http://compie.ru/wp-content/plugins/formcraft/file-upload/server/content/files/161382604411c9---molazezitusijudux.pdfIn PDF document text
    • http://fanghsin.com/uploads/files/202109100459504276.pdfIn PDF document text
    • http://feuerwehr-mittenwalde.de/mediathek/files/zijofanufapudunixibu.pdfIn PDF document text
    • http://hermanosgolbano.com/admin/fckeditor/editor/filemanager/connectors/phpfile/kekuwowerugogepevixo.pdfIn PDF document text
    • http://tuecpa.com/file_media/file_image/file/gewod.pdfIn PDF document text
    • https://www.pietri-automobiles.com/wp-content/plugins/super-forms/uploads/php/files/fmi52aurjonhvi55ikv69nd4kf/godijadufojapoparidilavi.pdfIn PDF document text
    • https://vegas-shop.net/uploads/files/zutasax.pdfIn PDF document text
    • http://aviafond.ru/userfiles/file/63604635718.pdfIn PDF document text
    • https://xn--atpta-nfb.lv/images/userfiles/files/zenapawunuzemubojug.pdfIn PDF document text
    • http://cluboutletmoto.net/campannas/file/65613990734.pdfIn PDF document text
    • http://dakhoanhanai.com/images/files/bumepa.pdfIn PDF document text
    • https://www.lesson-online.org/wp-content/plugins/super-forms/uploads/php/files/lno2u53vedr8v8sis3jqmoh0d1/busazivapiluwivenor.pdfIn PDF document text
    • https://feedproxy.google.com/~r/1eyvgo/aqOO/~3/3CAf4wW3hvY/uplcv?utm_term=restringing+a+classical+guitarPDF 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_off0000f694.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xF694 10432 bytes
SHA-256: da105faaa7910e9bd2bb8c75b74698d740ef05c53c0dba9cb5c7b4a79c7580ca
font_01_sfnt_off00010e5b.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x10E5B 18492 bytes
SHA-256: 66b3db9061c5abee27faa5730b1bb9a5fd5f7c2c7bdacffa5e84500c7d51fabc
font_02_sfnt_off00013d47.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x13D47 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1