Malicious PDF — malware analysis report

Static analysis result for SHA-256 6cfdc6f9b972ece8…

MALICIOUS

PDF

64.6 KB Created: 2021-04-26 11:42:53 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 4.8.7) First seen: 2021-05-23
MD5: 4ccb6bac8562de54410e659b627922ed SHA-1: 4b0f0f427b4ea3debb9fa84ebed661f39bb3300d SHA-256: 6cfdc6f9b972ece8366d2bf4f72c3cc30344f1daca29006107ebe55017a38437
126 Risk Score

Malware Insights

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

The PDF file was flagged by ML classifiers and ClamAV as malicious, specifically as a phishing trojan. It contains numerous embedded URLs, with one pointing to a suspicious domain ('klm3fg.grhosting.cz') that is likely part of a link farm designed to redirect users. The document body, though heavily obfuscated, suggests a lure related to a 'digital signal processing proakis 3rd edition solution manual pdf', indicating a phishing attempt to trick users into visiting a malicious site.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9996

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://klm3fg.grhosting.cz/sites/default/files/webform/files/40110328039.pdf In PDF document text
    • http://www.guninetwork.org/system/files/webform/heirri_proposals/nuxikovevevugodir.pdfIn PDF document text
    • https://ambrose.edu/sites/default/files/webform/82598578892.pdfIn PDF document text
    • https://www.enwidth.com/sites/default/files/webform/resumes/noranixuguwetepefosobad.pdfIn PDF document text
    • http://www.muttypawsacademy.com/sites/default/files/webform/vaccines/89533113822.pdfIn PDF document text
    • https://vectorcorp.net/sites/default/files/webform/resume/tefofavokalozigukar.pdfIn PDF document text
    • http://www.pbttphtk.gov.my/sites/default/files/webform/vojazasazobixupolaxi.pdfIn PDF document text
    • https://www.enwidth.com/sites/default/files/webform/resumes/95374483905.pdfIn PDF document text
    • http://www.ascendercorp.com/In PDF document text
    • http://www.ascendercorp.com/typedesigners.htmlIn PDF document text
    • https://feedproxy.google.com/~r/Uplcv/~3/BvfzZFkJO3s/uplcv?utm_term=digital+signal+processing+proakis+3rd+edition+solution+manual+pdfPDF link annotation
    • https://printandmail.princeton.edu/system/files/webform/26360011081.pdfIn PDF document text
    • https://www.healthdata.org/sites/default/files/resumes/18848190838.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_off0000baf1.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xBAF1 5704 bytes
SHA-256: b8e31263c5d3365b73184ee23a3a87044788abaa1a9a946c4fb7d16135e6c87e
font_01_sfnt_off0000ce51.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xCE51 10832 bytes
SHA-256: 41a17783e436eb720123a8e69a6199ec4d52be0b44c01fb59ed000f8e76c2411

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