Malicious PDF — malware analysis report

Static analysis result for SHA-256 b91ac31be7d4f9eb…

MALICIOUS

PDF

69.3 KB Created: 2021-10-04 03:54:41 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-11-20
MD5: a3e75005cc6d4662eeb073bd49d24ee0 SHA-1: 5285d5074879a08feae80eac07aebe61573dfa3b SHA-256: b91ac31be7d4f9ebc59fe5aad89ff8e686020e1f157754d5ef072e24448aa31c
126 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment

The file was detected as malicious by ML classifiers and ClamAV, indicating a high likelihood of malicious intent. It contains numerous embedded URLs, many of which point to PDF files on potentially disposable domains, suggesting a link farm or redirection mechanism. The PDF_SEO_DISPOSABLE_LINK_FARM heuristic further supports this, indicating a tactic to obscure the true destination. While no scripts were explicitly extracted, the nature of the heuristics and the presence of many external links suggest the PDF is designed to redirect users to malicious sites, likely for phishing or further payload delivery.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9965

Heuristics 5

  • ClamAV: Pdf.Phishing.Trojan-d2528dad23a95d95-d2528dad23a95d95-10044376-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Phishing.Trojan-d2528dad23a95d95-d2528dad23a95d95-10044376-0
  • 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://ume.civilkozpont.hu/uploads/file/91167931548.pdf In PDF document text
    • http://www.siscbolivia.com/admin/uploaded/fck/file/36850205006.pdfIn PDF document text
    • http://capableapp.com/uploads/files/buwazudomuseva.pdfIn PDF document text
    • http://image.dlib.vn/libedu/news/bachviet/20210927/file/wijavogujetakumemozikav.pdfIn PDF document text
    • https://www.autopsrus.com/ckfinder/userfiles/files/lulubupupulokasirakedife.pdfIn PDF document text
    • http://escuelasfutbol8.com/docs/files/35080798550.pdfIn PDF document text
    • https://institut-arabe.org/ckfinder/userfiles/files/fuxudejorikubinizorazak.pdfIn PDF document text
    • https://eltdb.com/UserFiles/files/zokapigemeji.pdfIn PDF document text
    • https://ximangcampha.vn/upload/files/ridifoniboxepiwep.pdfIn PDF document text
    • http://www.benyowsky.com/resources/files/98981808284.pdfIn PDF document text
    • http://stowarzyszeniemalyksiaze.eu/img/upload/files/18714169408.pdfIn PDF document text
    • http://kaitianjinghua.cn/admin/userfiles/file/202109170705246754.pdfIn PDF document text
    • http://goddesshair.net/upload/users/files/15939729359.pdfIn PDF document text
    • http://dgkno.cn/upload/sojoxiporut.pdfIn PDF document text
    • https://elegune.net/files/galeria/files/tilofisi.pdfIn PDF document text
    • http://ottomaniantextile.com/userfiles/file/24032637382.pdfIn PDF document text
    • https://livresdarts.com/ckfinder/userfiles/files/78449392412.pdfIn PDF document text
    • http://labotinnghia.com/img/files/33858023519.pdfIn PDF document text
    • http://numere-mopede.ro/mm/file/nesiram.pdfIn PDF document text
    • https://gimenezricarte-deltabogados.com/ckfinder/userfiles/files/dogaxinolifexigubebaliv.pdfIn PDF document text
    • http://dc-a0dcf319a153.breakthroughsport.com/userfiles/files/70333500194.pdfIn PDF document text
    • https://listocrm.com/userfiles/files/mubobuxotogix.pdfIn PDF document text
    • https://feedproxy.google.com/~r/Uplcv/~3/GLLx1DTH0VQ/uplcv?utm_term=termination+letter+due+to+non+performancePDF 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_off0000ae10.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xAE10 10676 bytes
SHA-256: 11c95e58e1f7cc146571e07ed7cb01466aed9cc60e43861128c1f84510e6d8e1
font_01_sfnt_off0000c672.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xC672 16184 bytes
SHA-256: bf185c8e139a16b089e491458ae3ffc5886a123a2004f08054ab51c017a5cf1f
font_02_sfnt_off0000ef91.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xEF91 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1