Malicious PDF — malware analysis report

Static analysis result for SHA-256 a35963f1ff85812b…

MALICIOUS

PDF

70.2 KB Created: 2021-04-18 15:48:18 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 4.8.7) First seen: 2021-05-29
MD5: f856751445d7a196867aa79382038c9b SHA-1: 1599dc0d5d206110a61c2ec4bc61c7360e86b079 SHA-256: a35963f1ff85812ba62588c4fc3727e7d073cfb7a4f8d63f346f5e42fa1b2530
134 Risk Score

Malware Insights

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

The PDF document is identified as malicious by ML classifiers and ClamAV, indicating a phishing or trojan payload. The presence of numerous external URIs, many pointing to disposable hosting, suggests a link farm designed to obscure the ultimate malicious destination. While no scripts were explicitly extracted, the PDF structure and heuristic firings point towards a malicious workflow, likely involving the exploitation of PDF vulnerabilities or social engineering to trick the user into downloading further malware.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9998

Heuristics 6

  • 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.
  • Visual download / call-to-action button lure low SE_DOWNLOAD_BUTTON
    Document contains a call-to-action phrase ('Click here to download', 'Download Now', etc.) — low-signal unless other findings point to a malicious workflow
  • 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://www.sumnercountyhospital.org/sites/default/files/webform/72664382884.pdf In PDF document text
    • https://www.enwidth.com/sites/default/files/webform/resumes/75468476758.pdfIn PDF document text
    • https://www.woonsocketri.org/system/temporary/webform/mupiroto.pdfIn PDF document text
    • https://ambrose.edu/sites/default/files/webform/59680287402.pdfIn PDF document text
    • http://russian-ice-spb.ru/sites/default/files/webform/files/77599308563.pdfIn PDF document text
    • https://architecturaldesigninc.com/sites/default/files/masugikiretige.pdfIn PDF document text
    • https://ambrose.edu/sites/default/files/webform/juremetepatofuf.pdfIn PDF document text
    • https://ambrose.edu/sites/default/files/webform/61391242106.pdfIn PDF document text
    • https://www.a1touchsolution.nl/sites/default/files/dovav.pdfIn PDF document text
    • https://www.osgeurope.com/sites/osg-corporate.dev/files/webform/memirudomonejusowanasu.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/PmAiG5ZyT-k/uplcv?utm_term=the+go-giver+chapter+summaryPDF link annotation
    • https://www.ice.cam.ac.uk/sites/www.ice.cam.ac.uk/files/webform/7842358922.pdfIn PDF document text
    • https://www.vub.be/sites/vub/files/webform/ludazerubadariwevulefaxu.pdfIn PDF document text
    • https://www.vub.be/sites/vub/files/webform/lijulur.pdfIn PDF document text
    • https://thesanfordschool.asu.edu/sites/default/files/webform/moxogugudufagelo.pdfIn PDF document text
    • https://minorsoncampus.princeton.edu/system/files/webform/xadumiwedom.pdfIn PDF document text
    • https://community.princeton.edu/system/files/webform/setokan.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_off0000d629.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xD629 5456 bytes
SHA-256: 58026cd8019f22b4411ff018208c63d914018123ed359b9d0beb62e5e0abe6a4
font_01_sfnt_off0000e8ac.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xE8AC 10244 bytes
SHA-256: 0fce74a652a762220fcb9ce31c69822803364194018c9dc09d91c4d4b189c0a0

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