Malicious PDF — malware analysis report

Static analysis result for SHA-256 41f52abaf4c73c41…

MALICIOUS

PDF

73.4 KB Created: 2021-02-25 05:40:31 +02:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 4.8.7) First seen: 2021-11-21
MD5: a53b174bfccc2fefd3b0f3081865c620 SHA-1: a922bfb53c5d8838bbfbf4cb24767c3e2f937c83 SHA-256: 41f52abaf4c73c4184ef144d61a2f0a74b763031630556059eaa06362dd84f32
156 Risk Score

Malware Insights

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

The file is a PDF that masquerades as educational content ('English grammar practice exercises online'). It contains a significant number of external links, as indicated by the PDF_SEO_LINK_FARM heuristic, with one prominent URL being https://jacksth.ru/strik. The ClamAV detection and ML classifier strongly suggest malicious intent, likely phishing or malware distribution via the numerous linked PDFs.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9997

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 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.
  • 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://jacksth.ru/strik?utm_term=english+grammar+practice+exercises+online PDF link annotation
    • http://vamoktin.ru/tijenutezesilixusykww.pdfIn PDF document text
    • https://fiwugepupuladav.weebly.com/uploads/1/3/4/7/134740110/jipute.pdfIn PDF document text
    • https://wifuduwelu.weebly.com/uploads/1/3/2/8/132814355/38e7ff.pdfIn PDF document text
    • https://gakujoxabusu.weebly.com/uploads/1/3/5/3/135394689/a0c2976.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/dujepav/5892924642.pdfIn PDF document text
    • https://s3.amazonaws.com/kakef/97177714653.pdfIn PDF document text
    • https://s3.amazonaws.com/ritoma/alcohols_and_phenols_lab_answers.pdfIn PDF document text
    • https://s3.amazonaws.com/lovomijelun/xizabibepelepezaseromij.pdfIn PDF document text
    • https://s3.amazonaws.com/purawuma/sijirezamewex.pdfIn PDF document text
    • https://s3.amazonaws.com/zulezov/bumedifigadatifum.pdfIn PDF document text
    • https://s3.amazonaws.com/lakujusitejojet/zusojofixenevobujedafiw.pdfIn PDF document text
    • https://s3.amazonaws.com/wisuw/padazisulipogutizasol.pdfIn PDF document text
    • https://s3.amazonaws.com/wupagivoz/android_checkbox_custom_background.pdfIn PDF document text
    • https://s3.amazonaws.com/rodiligarexo/82408081262.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_off0000e088.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xE088 5372 bytes
SHA-256: a1779ffd852e9296949685db973eadbddf932036cfdab01ac892ba950104c13f
font_01_sfnt_off0000f2ad.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xF2AD 11244 bytes
SHA-256: d66ec3e246ceedc8b41e8e6dd7417fd1d5ecfc673791c798fbdb77b96670c164

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