Malicious PDF — malware analysis report

Static analysis result for SHA-256 9db1bbe36beda13c…

MALICIOUS

PDF

79.5 KB Created: 2021-04-25 15:34:35 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 4.8.7)
MD5: 571786a14e161c1c396f1c44c86938f0 SHA-1: 2e954b827d696df274e604bfa917cebd3d39a35a SHA-256: 9db1bbe36beda13c549b0b14172c6405131f7df0208ba9981ac0c165ae708e20
156 Risk Score

Malware Insights

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

The PDF file is identified as malicious by ClamAV and an ML classifier, and it contains a large number of external links, suggesting a link farm or phishing attempt. The document body, though heavily obfuscated, contains a reference to 'Huckleberry Finn audiobook chapter 28' and the authoring application 'wkhtmltopdf', indicating a lure to disguise malicious intent. The presence of numerous external PDF links points towards a strategy to distribute further malicious content or engage in SEO manipulation for malicious purposes.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9998

Heuristics 5

  • 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.
  • ClamAV: Pdf.Phishing.Trojan-d2528dad23a95d95-d2528dad23a95d95-10044376-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Phishing.Trojan-d2528dad23a95d95-d2528dad23a95d95-10044376-0
  • 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/strik?utm_term=huckleberry+finn+audiobook+chapter+28
    • https://fufivivol.weebly.com/uploads/1/3/0/8/130873849/3f6267b6950.pdf
    • https://cdn.sqhk.co/jopuromug/jILX59B/12931608785.pdf
    • https://static.s123-cdn-static.com/uploads/4461249/normal_5fc99410bbd64.pdf
    • https://cdn.sqhk.co/vawapisoxe/sacYGja/blue_bot_class_bundle.pdf
    • https://bubokadorododu.weebly.com/uploads/1/3/4/7/134758236/rozobojobibudun-lakaloxedim-piwopokisu-beburefe.pdf
    • https://static.s123-cdn-static.com/uploads/4495976/normal_5fca732531b6f.pdf
    • https://kakejomoweva.weebly.com/uploads/1/3/4/6/134674311/kiporulewowukipowa.pdf
    • https://soxoxalumowaju.weebly.com/uploads/1/3/4/7/134768556/5539282.pdf
    • https://cdn-cms.f-static.net/uploads/4368976/normal_60654c726f583.pdf
    • https://betutinixe.weebly.com/uploads/1/3/4/4/134481053/savasovige_poduxuketoneva_zudovuvekiz_rosavoti.pdf
    • https://zonerizarom.weebly.com/uploads/1/3/4/3/134310007/likado.pdf
    • https://xumipapabof.weebly.com/uploads/1/3/4/6/134609146/484999.pdf
    • http://www.ascendercorp.com/
    • http://www.ascendercorp.com/typedesigners.html
    • http://www.daltonmaag.com/
    • https://4c2674ec-1430-4cec-a455-d6a35d10586e.filesusr.com/ugd/38955b_95a4ca960c404f9a9a271ee96ba7bf55.pdf?index=true
    • https://d1ced4a1-fa29-4c66-b583-77209f32159a.filesusr.com/ugd/c88d8b_105e033dabbf4b20a93f528fa264b5e7.pdf?index=true
    • https://945c5b1a-9feb-4a08-b72d-c905ca1b1520.filesusr.com/ugd/27135d_f896e63ea42848118f44ebe3ec4fbb70.pdf?index=true
    • https://a9864912-ad24-422b-99f3-2d90f7703507.filesusr.com/ugd/d6af85_d79941c0beaf40838cd8e00a93a8773d.pdf?index=true
    • http://www.w3.org/1999/02/22-rdf-syntax-ns#
    • http://purl.org/dc/elements/1.1/
    • http://ns.adobe.com/pdf/1.3/
    • http://ns.adobe.com/xap/1.0/
    • http://ns.adobe.com/xap/1.0/mm/
    • http://ns.adobe.com/xap/1.0/rights/
    • http://scripts.sil.org/OFL

Extracted artifacts 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
font_00_sfnt_off0000e9bc.bin
cc4b6eb8898b9847387bf4fc4adb60305eaedd398d5d654970abe8b65f5ce064		 pdf-font-stream PDF embedded font (sfnt) at offset 0xE9BC 5540 bytes
font_01_sfnt_off0000fc7f.bin
6635cce8e926e17992cf60b652f7b726f14b8a3332431e63b9b127d9abe6d4dd		 pdf-font-stream PDF embedded font (sfnt) at offset 0xFC7F 11400 bytes
font_02_sfnt_off0001227e.bin
cd94ef65598b1866d0653cdd88243d989fd81359c0e770c2d3a4858f1c2f6d34		 pdf-font-stream PDF embedded font (sfnt) at offset 0x1227E 4324 bytes

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