Malicious PDF — malware analysis report

Static analysis result for SHA-256 af93ddff1fb187b7…

MALICIOUS

PDF

74.2 KB Created: 2021-03-14 19:55:56 +02:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 4.8.7)
MD5: 48fb532867faba100ac6304b9d3ad612 SHA-1: 13f735ecffd50e911eaceb60537470df0fe60e3c SHA-256: af93ddff1fb187b79b8ffbcd9612f40f80a00a105e90f611a462f528be81f7d4
156 Risk Score

Malware Insights

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

The PDF file, generated by wkhtmltopdf, contains a large number of external links, identified as a 'PDF_SEO_LINK_FARM' heuristic. The document body, though heavily obfuscated, contains text related to 'infinitives exercises with answers for class 7', suggesting a lure. The presence of ClamAV detection and ML classification strongly indicates malicious intent, likely related to phishing or distributing malware via the numerous linked PDFs.

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-d2568dad23a94d95-d2568dad23a94d95-10044375-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Phishing.Trojan-d2568dad23a94d95-d2568dad23a94d95-10044375-0
  • 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/123?utm_term=infinitives+exercises+with+answers+for+class+7
    • https://cdn.sqhk.co/benanejufa/UlQW8jh/age_of_conquest_iv_hack_download.pdf
    • https://xakowuval.weebly.com/uploads/1/3/5/3/135316831/1217742.pdf
    • https://vuwonogi.weebly.com/uploads/1/3/5/3/135300132/9986414.pdf
    • http://lubevos.scienceontheweb.net/maven_tutorial_udemy.pdf
    • http://figejewumoposes.getenjoyment.net/how_many_volumes_of_saga_are_out.pdf
    • https://gazobibulome.weebly.com/uploads/1/3/4/7/134775133/491727123b7a54.pdf
    • https://cdn-cms.f-static.net/uploads/4454301/normal_600b441150d8d.pdf
    • https://fawukudaboguris.weebly.com/uploads/1/3/4/3/134353338/d7bb5ce433.pdf
    • https://static.s123-cdn-static.com/uploads/4421049/normal_5ffa2d6a6b1b7.pdf
    • https://cdn.sqhk.co/zejegure/yYhiXrg/nike_sport_apple_watch_band_38mm.pdf
    • http://www.ascendercorp.com/
    • http://www.ascendercorp.com/typedesigners.html
    • http://www.daltonmaag.com/
    • https://uploads.strikinglycdn.com/files/b4284592-6c36-4cb5-96e7-e8aff2170f53/97832613919.pdf
    • https://uploads.strikinglycdn.com/files/31e9d9a8-3d7e-4729-ad1d-f66723a4c0b3/papaxesobovi.pdf
    • https://uploads.strikinglycdn.com/files/35a238cf-49a7-4fe6-aa73-d83a112fd92a/60938053274.pdf
    • https://uploads.strikinglycdn.com/files/3f98208f-a252-45cd-b7ab-fa344c7be6df/football_exercises_for_8_year_olds.pdf
    • https://uploads.strikinglycdn.com/files/14baa4da-4ce4-4943-9e87-130bbec7f7d3/jolalareparimo.pdf
    • https://uploads.strikinglycdn.com/files/33cd1ee6-87e7-469d-a5ec-20beec4601ce/how_much_to_replace_lost_nhs_hearing_aid.pdf
    • 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_off0000d977.bin
ff4031411069e6aa1c59da5269375e0f526459d36a1030deb0ddd5eb754734af		 pdf-font-stream PDF embedded font (sfnt) at offset 0xD977 4992 bytes
font_01_sfnt_off0000ea7c.bin
087ac5b38714484c6b0f805f34c795fe671f62856f9743148fde360bd2c53e5a		 pdf-font-stream PDF embedded font (sfnt) at offset 0xEA7C 10256 bytes
font_02_sfnt_off00010d91.bin
9f355172d696dda274cac500966718f112ce76951f19577ac4888987ea6471b2		 pdf-font-stream PDF embedded font (sfnt) at offset 0x10D91 4324 bytes

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