Malicious PDF — malware analysis report

Static analysis result for SHA-256 a1ca8737ce792dce…

MALICIOUS

PDF

77.8 KB Created: 2021-05-25 13:52:06 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 4.8.7) First seen: 2021-11-21
MD5: e35a9b7e1de7a8c9ef8b869e8cc69278 SHA-1: e05d9a6026d71aba78e8e230b05abe1188cb2e5b SHA-256: a1ca8737ce792dce5375cc9feb2795d920ac7f6be94df3c32c3e24a3d117fb8d
156 Risk Score

Malware Insights

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

The PDF contains a large number of external links, identified as a 'PDF_SEO_LINK_FARM' heuristic. One of these links, 'https://leonvi.ru/strik?utm_term=biddeford+school+department+teacher+contract', is flagged as an external URI. The ML classifier and ClamAV also strongly indicate maliciousness, suggesting the PDF is used to redirect users to potentially harmful content or for SEO abuse. No scripts were extracted, but the structure points to a malicious document.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9993

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://leonvi.ru/strik?utm_term=biddeford+school+department+teacher+contract PDF link annotation
    • https://static.s123-cdn-static.com/uploads/4460708/normal_5fe0bca36b3d0.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4380068/normal_603fd2574075d.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4368748/normal_600f02a6dceaa.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4401540/normal_601eacf71b36f.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4423714/normal_60380e751f6a8.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4425919/normal_6027dd1119246.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4410727/normal_6028b247c6144.pdfIn PDF document text
    • https://xugojegisonixen.weebly.com/uploads/1/3/4/6/134684264/407ed2dd.pdfIn PDF document text
    • https://bitojobuf.weebly.com/uploads/1/3/4/8/134892495/5fc08fa7db.pdfIn PDF document text
    • https://static.s123-cdn-static.com/uploads/4383572/normal_5fe35a6a746d2.pdfIn PDF document text
    • https://fapufeloku.weebly.com/uploads/1/3/1/0/131071019/gafufak_lugubasimamokiw.pdfIn PDF document text
    • https://bobuvuxatuf.weebly.com/uploads/1/3/7/5/137519798/6646613.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4449974/normal_60274deeb5dd4.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4480155/normal_604871160ecd0.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4501201/normal_601bb32248e67.pdfIn PDF document text
    • http://www.ascendercorp.com/In PDF document text
    • http://www.ascendercorp.com/typedesigners.htmlIn PDF document text
    • https://uploads.strikinglycdn.com/files/a43350fd-8757-4fde-95ce-dc1f9f722068/is_sodastream_really_better_for_the_environment.pdfIn PDF document text
    • https://uploads.strikinglycdn.com/files/29e0890a-aeeb-45a0-96ed-dbcc76bc8212/what_is_a_continuous_derivative.pdfIn PDF document text
    • https://uploads.strikinglycdn.com/files/6110c438-17af-4804-b898-4b441593f1ac/where_is_the_reset_button_on_oil_furnace.pdfIn PDF document text
    • https://uploads.strikinglycdn.com/files/01949398-5b19-4d45-bf97-19300bf42808/kexetavaxupupogijoluro.pdfIn PDF document text
    • https://uploads.strikinglycdn.com/files/9d489e70-45bc-4d0f-aaf0-8a564214500c/fovebudisetitajukajas.pdfIn PDF document text
    • https://uploads.strikinglycdn.com/files/721fa94d-09cb-435c-a97f-849e98af2f7e/13132544316.pdfIn PDF document text
    • https://uploads.strikinglycdn.com/files/f3ec41c2-8b05-4963-b7bd-1ec147100e76/37521877728.pdfIn PDF document text
    • https://uploads.strikinglycdn.com/files/7d8e4b62-b5a6-4842-a01b-7f284ac03764/what_if_netflix_series_season_2_release_date.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_off0000f3fd.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xF3FD 5444 bytes
SHA-256: 31286bfbecbebb7f8102ce5f819d5c8e095ae2404691e82705ec8a80e2c776eb
font_01_sfnt_off00010665.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x10665 10312 bytes
SHA-256: 34789d880e1f45f3af7b0090c5a47f90b155831dabefa2cdadbaa11bd0b7e3d1