Malicious PDF — malware analysis report

Static analysis result for SHA-256 51f8aeba165d4b2b…

MALICIOUS

PDF

81.6 KB Created: 2021-03-02 01:45:03 +02:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 4.8.7) First seen: 2021-11-22
MD5: 6e1a51e0d7551297de3edbe13bff7d0d SHA-1: 7e090b8dec3fd38c5b3dda461bdfcbae384cdbf3 SHA-256: 51f8aeba165d4b2be6c74233075fbb0eedad3b7c289d36fe478e079bf038842c
126 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1059.007 JavaScript

The PDF file was flagged by ClamAV as a phishing trojan and a machine learning classifier indicated a high probability of maliciousness. It contains numerous embedded URLs, with one prominent URL pointing to 'zajinet.ru' and containing a search term related to Excel VBA, suggesting a lure. The heuristic 'PDF_SEO_DISPOSABLE_LINK_FARM' indicates the PDF is part of a link farm on disposable hosting, further supporting a malicious intent to redirect users. No scripts were extracted, but the overall structure and URL distribution point towards a phishing or malware distribution campaign.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9997

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 https://zajinet.ru/123?utm_term=excel+vba+find+text+between+two+strings PDF link annotation
    • https://cdn-cms.f-static.net/uploads/4370073/normal_5fdb11463af60.pdfIn PDF document text
    • http://ruwemipuwev.mypressonline.com/kifukoso.pdfIn PDF document text
    • http://eglo.club/5814953975094spz.pdfIn PDF document text
    • https://static.s123-cdn-static.com/uploads/4459777/normal_6002aa28548db.pdfIn PDF document text
    • http://storezone.info/widaxititezemazoytp.pdfIn PDF document text
    • https://static.s123-cdn-static.com/uploads/4392210/normal_5fca150c7cca4.pdfIn PDF document text
    • http://mosuxuvemuzuwex.mywebcommunity.org/ginukowoniwomo.pdfIn PDF document text
    • http://uose.xyz/can_you_capitalize_fatherrydf1.pdfIn PDF document text
    • http://pazadixokumox.sportsontheweb.net/76784725844.pdfIn PDF document text
    • http://artdebug.site/85795208258ttnsr.pdfIn PDF document text
    • http://www.ascendercorp.com/In PDF document text
    • http://www.ascendercorp.com/typedesigners.htmlIn PDF document text
    • http://jimarol.myartsonline.com/sekiti.pdfIn PDF document text
    • http://vurisadazuxe.epizy.com/nuguguxozelimikebap.pdfIn PDF document text
    • http://pikubub.onlinewebshop.net/2021021941.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://scripts.sil.org/OFLIn PDF document text

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
font_00_sfnt_off00010104.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x10104 5508 bytes
SHA-256: 9fa5feb90141a89874b6b2034da95f64dc1dfb2ec8a65d5159594f07cfbe3ea9
font_01_sfnt_off000113ea.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x113EA 10912 bytes
SHA-256: 20fd585e1afe7b12f842cc183ebb8887ea2e41155c490c27a2fa200a43502c1d

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