Malicious PDF — malware analysis report

Static analysis result for SHA-256 b7a3b785a48ea1f0…

MALICIOUS

PDF

79.0 KB Created: 2021-03-28 22:22:49 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 4.8.7) First seen: 2021-08-25
MD5: 7b1834be173c0fe3861c28b5bc5d0591 SHA-1: d1f169d82fac8340c045f8d11ec0ed81ce09109c SHA-256: b7a3b785a48ea1f09ffbc0d49f9591131b3c3206d647acdba9b4c3183956d02f
186 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious Link

The PDF file was identified as malicious by ClamAV and an ML classifier, indicating a high likelihood of malicious intent. Heuristics indicate it functions as a link farm, containing numerous external links, with one prominent URL pointing to 'jacksth.ru'. The document body, though heavily obfuscated, contains metadata suggesting it was generated by wkhtmltopdf, a tool often used to create PDFs from web content, further supporting the link farm hypothesis.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9994

Heuristics 6

  • 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.
  • 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://jacksth.ru/award?keyword=bibliology+pdf+books PDF link annotation
    • https://cdn.sqhk.co/kugefiruxat/iehjrhk/95560471491.pdfIn PDF document text
    • http://beststudent.space/37545273423f6eqi.pdfIn PDF document text
    • http://fruittea.space/do_deep_freezers_have_a_reset_buttonengyj.pdfIn PDF document text
    • http://online-sistem.site/837683772458s22y.pdfIn PDF document text
    • http://myluckywin.site/wamanevib8n4qj.pdfIn PDF document text
    • http://bilkaita.space/psr_e463_owners_manualp8fbz.pdfIn PDF document text
    • https://cdn.sqhk.co/vimerokil/ha94hg3/sozidusofogomote.pdfIn PDF document text
    • http://www.ascendercorp.com/In PDF document text
    • http://www.ascendercorp.com/typedesigners.htmlIn PDF document text
    • https://0443db59-9f9d-4031-b786-8a5723798135.filesusr.com/ugd/ab62d6_adcd5bb67e3d4a2094969821b27a7a97.pdf?index=trueIn PDF document text
    • https://s3.amazonaws.com/wifukedot/developing_writing_skills_in_french.pdfIn PDF document text
    • https://50037ee0-0691-4a53-bdc2-b2f8f795cfa6.filesusr.com/ugd/b41a9a_c43c5f04527644ee81610e150175ac9f.pdf?index=trueIn PDF document text
    • https://e8b83640-91e4-44a0-a69f-c2468797902f.filesusr.com/ugd/ee4a13_fb406952dbb14c4298fd4f13a5574124.pdf?index=trueIn PDF document text
    • https://uploads.strikinglycdn.com/files/50d54e00-c997-4c43-8df4-c7ae3d69eb4c/will_durant_quotes_excellence.pdfIn PDF document text
    • https://d6504552-49b0-4b7d-b1ff-94f9e1082b83.filesusr.com/ugd/1f0558_49ed0dc095e74d7ea26a3d9dd854a83c.pdf?index=trueIn PDF document text
    • https://eee5dff6-7331-416e-acdf-593d0c386862.filesusr.com/ugd/21e9e0_e8766df9bf004a9ba4d6bfb92e966d76.pdf?index=trueIn PDF document text
    • https://uploads.strikinglycdn.com/files/81d0ae73-60a8-41a2-b412-1cc0967b735c/kaxepus.pdfIn PDF document text
    • https://2b08c346-38d8-4763-b559-bb9d4fff2313.filesusr.com/ugd/40c9d6_9a96e80440f14b6f8914b1c9d03d23d1.pdf?index=trueIn PDF document text
    • https://uploads.strikinglycdn.com/files/57e4d84a-04c2-44bf-82a3-725b09bd6d64/how_do_i_reset_my_pioneer_radio_bluetooth.pdfIn PDF document text
    • https://91c7bc9f-df77-4dbd-ae51-8bcf521f3e61.filesusr.com/ugd/1df9ea_743b1aac6b1b4beea5503a76411c1bdc.pdf?index=trueIn PDF document text
    • https://s3.amazonaws.com/tuxexi/hospital_exposure_narrative_report.pdfIn PDF document text
    • https://s3.amazonaws.com/jeworurowam/latest_itunes_windows_10.pdfIn PDF document text
    • https://383fd46b-cc41-47b7-9379-19c19d7bb1fe.filesusr.com/ugd/81c43a_b7f228f299b749d3ac3b75e4ca2fe056.pdf?index=trueIn PDF document text
    • https://uploads.strikinglycdn.com/files/2f8fd2fe-7473-45f9-b0a8-d3ea6e46cbe5/wonupul.pdfIn PDF document text
    • https://s3.amazonaws.com/padanivozeb/92313763648.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_off0000f73e.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xF73E 5256 bytes
SHA-256: 45f6f68c5a3abbcdcda380581b5a6492802d33e0489fc80cc0a0dbb6d11b2c7d
font_01_sfnt_off0001094a.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x1094A 10532 bytes
SHA-256: a0338bc2a175318b153a51150d74fa5ef9f3f6ed74a6ad0021cf0bf45b2a6c02