Malicious PDF — malware analysis report

Static analysis result for SHA-256 51bb8aaf84c14798…

MALICIOUS

PDF

67.2 KB Created: 2020-11-24 04:36:12 +02:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 4.8.7) First seen: 2021-09-16
MD5: f87201e1ddad50c99f7666805f8cd3e6 SHA-1: 9e5b0a089b976ca56746f2ef8872fd4f21af4bde SHA-256: 51bb8aaf84c14798450b14365f57a889e33a07a4e7d24b83673d386c59ea5e3b
214 Risk Score
Tags
free-cdn-ebook-manual-lure

Malware Insights

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

The PDF contains a large number of embedded links, many of which point to redirector infrastructure or potentially malicious content, as indicated by the 'PDF_MALICIOUS_REDIRECTOR_LINK' and 'PDF_SEO_LINK_FARM' heuristics. The ML classifier and ClamAV also flagged this PDF as malicious, suggesting it is part of a phishing or malware distribution campaign. The document body, though heavily obfuscated, contains references to 'wkhtmltopdf' and a date, indicating it was likely generated programmatically to host these links.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9998

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
  • PDF links to known malicious redirector infrastructure critical PDF_MALICIOUS_REDIRECTOR_LINK
    PDF contains a clickable URI to redirector infrastructure used by a known malicious PDF SEO/adware delivery campaign. These documents typically rely on user interaction and redirect chains rather than a PDF parser vulnerability.
  • Small PDF contains mass external PDF link farm critical PDF_SEO_LINK_FARM
    Small PDF contains many clickable external PDF links, mostly clustered on one host. This matches generated SEO/link-farm PDF carriers used to route users into malicious or unwanted-software delivery chains, rather than a normal document citation pattern.
  • 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://ggtraff.ru/strik?utm_term=characters+in+annie+movie In PDF document text
    • https://cdn-cms.f-static.net/uploads/4475379/normal_5fbc1e5352294.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4420764/normal_5fa2a3c3da985.pdfIn PDF document text
    • https://bekijarodik.weebly.com/uploads/1/3/4/6/134617997/7237958.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4366351/normal_5fb3719739c85.pdfIn PDF document text
    • https://juladuwupib.weebly.com/uploads/1/3/4/7/134763366/13575b.pdfIn PDF document text
    • http://www.ascendercorp.com/In PDF document text
    • http://www.ascendercorp.com/typedesigners.htmlIn PDF document text
    • https://s3.amazonaws.com/jojitagifuva/gejaxiga.pdfIn PDF document text
    • https://s3.amazonaws.com/zirojopemup/74894152062.pdfIn PDF document text
    • https://s3.amazonaws.com/doxifuba/history_of_language_arts.pdfIn PDF document text
    • https://uploads.strikinglycdn.com/files/0dfc6ce8-de7a-4ebd-9e35-4a980618d50e/filafupetigewipibedid.pdfIn PDF document text
    • https://uploads.strikinglycdn.com/files/fc8ac119-8990-404b-9a82-e125844b1de3/zivanujixafalijukire.pdfIn PDF document text
    • https://s3.amazonaws.com/sazomo/certificato_di_conformit_auto.pdfIn PDF document text
    • https://s3.amazonaws.com/genedesowul/anatomy_and_physiology_visible_body_apk.pdfIn PDF document text
    • https://s3.amazonaws.com/tuxutedi/class_10_biology_chapter_2_notes.pdfIn PDF document text
    • https://uploads.strikinglycdn.com/files/f2349adb-7310-4abf-963f-b10aac6611a5/gakofosenujuvivelireg.pdfIn PDF document text
    • https://uploads.strikinglycdn.com/files/e0ce72e8-1fa8-461c-ad8b-2e3c1386c0fd/star_wars_essential_guide_to_warfare.pdfIn PDF document text
    • https://uploads.strikinglycdn.com/files/9f5a6d07-5ca4-41c0-af32-80ecd39d720b/20945823757.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_off0000cb92.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xCB92 4972 bytes
SHA-256: e2bdedb8e5a9e8297e887a5306a431dd98fb1874f0d23e69e6bc109be808b37b
font_01_sfnt_off0000dc4b.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xDC4B 10660 bytes
SHA-256: ef86df5a23604f153659d0b228915c671a2a2c2fc8755795cb5c5b29ed509973

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