Malicious PDF — malware analysis report

Static analysis result for SHA-256 a81498af53e39fc0…

MALICIOUS

PDF

77.9 KB Created: 2021-08-31 22:27:32 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-10-27
MD5: 4a18c4ab95de1ade746feb2965bf0d26 SHA-1: 6e3f4135c6b56567b7a434bc0ff09be6d2ef9721 SHA-256: a81498af53e39fc07971f7ba821900496989765eed451e0bda610250c242ccb3
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 it is likely a phishing or malware distribution tool. It contains numerous external links, many pointing to compromised WordPress upload directories, suggesting a link farm designed to redirect users to malicious content. The document body is heavily obfuscated and unreadable, providing no direct user-facing lure.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9976

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://laborke.ru/uplcv?utm_term=words+that+start+with+d+and+end+with+l PDF link annotation
    • https://bowenpainter.com/wp-content/plugins/formcraft/file-upload/server/content/files/1608f4ca12c508---visikavukodudodezar.pdfIn PDF document text
    • http://privateeducation.sg/verzsape/demo/upload/admin/files/5119790741.pdfIn PDF document text
    • http://denda.co.kr/ckfinder/userfiles/files/46436942517.pdfIn PDF document text
    • http://www.esthemed.ch/wp-content/plugins/formcraft/file-upload/server/content/files/160c8c66041db8---63049181346.pdfIn PDF document text
    • https://www.icslights.com/wp-content/plugins/super-forms/uploads/php/files/f3cc646b8838a95b6a5720d6c38b3d09/82164218352.pdfIn PDF document text
    • http://www.kmclogistics.com/wp-content/plugins/super-forms/uploads/php/files/df81888c1a0ec7602628c7519784481f/36112092965.pdfIn PDF document text
    • http://www.kinoimaging.nl/wp-content/plugins/formcraft/file-upload/server/content/files/160a6093930f93---4814174033.pdfIn PDF document text
    • https://debo-fit.be/userfiles/file///libivabopizatesal.pdfIn PDF document text
    • http://www.marsagri.com/wp-content/plugins/formcraft/file-upload/server/content/files/1606cc10c3bcbb---pafaxij.pdfIn PDF document text
    • http://aj-freight.com/ckfinder/userfiles/files/pabetam.pdfIn PDF document text
    • http://imssp.by/data/images/fxeditor/file/4955897780.pdfIn PDF document text
    • http://www.hollyskauaicondo.com/wp-content/plugins/formcraft/file-upload/server/content/files/161060aa44d75b---nabukarojadejitavonuwena.pdfIn PDF document text
    • https://www.criteriainvest.com.br/wp-content/plugins/super-forms/uploads/php/files/h1h5g05bgcaq5hq9j4b6bmj61e/82151533176.pdfIn PDF document text
    • https://studiogreenwich.ru/wp-content/plugins/super-forms/uploads/php/files/5e0ac89ff2ed932a952a8cbf99bab05a/xerafujomuxejimipuduz.pdfIn PDF document text
    • http://svx.su/ffile/file/90686005587.pdfIn PDF document text
    • https://shared401k.com/wp-content/plugins/super-forms/uploads/php/files/34f7d778e56212a87733e50c450c18d5/menak.pdfIn PDF document text
    • http://es-manzokudou.com/yamituki-n/uploads/files/41577988989.pdfIn PDF document text
    • http://southportrubbish.com/wp-content/plugins/formcraft/file-upload/server/content/files/160c45ff42c4ee---begutomiguxemopopirubije.pdfIn PDF document text
    • https://primeodontorj.com/wp-content/plugins/super-forms/uploads/php/files/f3fe7bd55e7058ba780382f388a77b92/vevowubeber.pdfIn PDF document text
    • https://accesoriosalmayor.com/images/userfiles/file/50302622162.pdfIn PDF document text
    • http://www.maoles.com/wp-content/plugins/formcraft/file-upload/server/content/files/160adea5fd9225---93853496505.pdfIn PDF document text
    • https://arerp.kr/data/file///82379860408.pdfIn PDF document text
    • https://asi-filter.pl/files/file/karedi.pdfIn PDF document text
    • 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_off0000ceef.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xCEEF 17288 bytes
SHA-256: af8b0c1bdf9d5f7210cc0b29fcca89aa72f597db1bdaf142361b31b205d07208
font_01_sfnt_off0000fa35.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xFA35 10424 bytes
SHA-256: 2f9f1dc0d64bfc676e3dabb9c3683ab8e91e7a0fe5afe806a78a0cd17f7cf9af
font_02_sfnt_off000111d4.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x111D4 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1

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