Malicious PDF — malware analysis report

Static analysis result for SHA-256 51ea0c24410413d4…

MALICIOUS

PDF

81.9 KB Created: 2021-09-08 13:50:06 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-10-16
MD5: 76c022c5bca1af3841b9c39d61007ee0 SHA-1: d7b5dd23b345f7653ebde2b6e909a0fc38549135 SHA-256: 51ea0c24410413d434673a73cd1ce23f44866e09081deb28b3b7f7cc9211f3c2
126 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious Link

The PDF was flagged by ML and ClamAV as malicious, with heuristics indicating it functions as a link farm. Multiple embedded URLs point to unknown or potentially malicious domains, suggesting an attempt to redirect users to harmful content. The document body is heavily obfuscated and appears to be non-readable content generated by wkhtmltopdf, further supporting the malicious intent.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9975

Heuristics 5

  • 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 http://thanhnienxp.com/vietkiendo/upload/file/63572316592.pdf In PDF document text
    • https://odlingfamily.com/userfiles/file/zatipetuwikuwim.pdfIn PDF document text
    • http://mingzhicc.com/userfiles/files/39492288108.pdfIn PDF document text
    • http://gzperson.com/uploadfile/files/retub.pdfIn PDF document text
    • https://grahampropertytax.com/wp-content/plugins/super-forms/uploads/php/files/b8c4966edf0657e7595d9e3d4f3a4e6b/tetisovafujusadufobojaxiv.pdfIn PDF document text
    • http://hoigolfbinhthuan.com/users/files/66690892721.pdfIn PDF document text
    • http://hk-bbc.com/upload/file/12370076728.pdfIn PDF document text
    • http://www.cerel.eu/images/wyswig_images/file/25360241583.pdfIn PDF document text
    • http://goodwill.pl/userfiles/file/16118225798.pdfIn PDF document text
    • https://gtnet-engine.com/ckfinder/userfiles/files/joduxatakal.pdfIn PDF document text
    • http://likebarcode.com/image/files/20210908_025800.pdfIn PDF document text
    • http://gurukripapublicschool.com/userfiles/file/vosebanat.pdfIn PDF document text
    • https://esteticarcare.com/wp-content/plugins/super-forms/uploads/php/files/d0631b4753d4cc87ff7f81a3a943a1a7/81234649589.pdfIn PDF document text
    • http://taiwangallant.com/uploads/files/202109030908077659.pdfIn PDF document text
    • https://hotelexpert.ro/uploads/files/57756748886.pdfIn PDF document text
    • https://arte-salon.ru/upload_picture/doregedu.pdfIn PDF document text
    • https://greenbins.ca/ckfinder/userfiles/files/76242571139.pdfIn PDF document text
    • http://hotelbasantresidency.com/uploads/tugosegataxo.pdfIn PDF document text
    • http://bebelino.ru/userfiles/file/nudikumowamubekatibufub.pdfIn PDF document text
    • https://festivaldelmaridaje.com/sgi_userfiles/userfiles/files/59480841743.pdfIn PDF document text
    • http://www.ortodonciaelisafarache.com/ckfinder/userfiles/files/58750211734.pdfIn PDF document text
    • http://wixoon.hu/upload/file/nivitubodezupapixelerapo.pdfIn PDF document text
    • https://www.jaegeraviation.com/ckfinder/userfiles/files/82300038846.pdfIn PDF document text
    • http://cloudinfo01.smartevolve.com/images/ckeditor/files/xejegurulosukofibamipib.pdfIn PDF document text
    • http://nriloan.jctoursandtravels.in/files/fixufu.pdfIn PDF document text
    • https://feedproxy.google.com/~r/1eyvgo/aqOO/~3/GLLx1DTH0VQ/uplcv?utm_term=dermatitis+seborreica+del+adulto+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://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_off0000d9a9.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xD9A9 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1
font_01_sfnt_off0000f1c0.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xF1C0 10920 bytes
SHA-256: 09f80d6ef2c3424c7a8cb19c6c89dc8bf6bda7ff0282d51bc6d99efc4c916a35
font_02_sfnt_off00010ad7.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x10AD7 18600 bytes
SHA-256: 6345621e912a3eff097c34d244ec232f535c56b0a20400c3da0be0c7c4bbcc75