Malicious PDF — malware analysis report

Static analysis result for SHA-256 37a19f1a4cd71a19…

MALICIOUS

PDF

70.5 KB Created: 2021-01-11 17:53:26 +02:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 4.8.7) First seen: 2021-11-02
MD5: 43d267c37c878e486aaa95e6d355b5e1 SHA-1: e7c29da826fae127c3ff0b6471d159d2c7690cd4 SHA-256: 37a19f1a4cd71a19ca0347b668f351f0113c5c9f20d8ce49cdf7b84dd4b3ed57
126 Risk Score

Malware Insights

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

The PDF file was flagged by ML classifiers and ClamAV as malicious, specifically as a phishing trojan. It contains numerous embedded URLs pointing to external domains, many of which are hosted on disposable domains and appear to be part of a link farm. The document body is heavily obfuscated and contains metadata suggesting it was generated by wkhtmltopdf, but no executable scripts were extracted.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9997

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 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://trafficel.ru/aws?utm_term=upsee+category+full+forms PDF link annotation
    • https://cdn-cms.f-static.net/uploads/4368998/normal_5f88fa757a4c3.pdfIn PDF document text
    • https://static.s123-cdn-static.com/uploads/4417664/normal_5ff867b1f3875.pdfIn PDF document text
    • https://site-1180563.mozfiles.com/files/1180563/nova_launcher_setup_twitter.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4449181/normal_5fa05d6f6d919.pdfIn PDF document text
    • https://site-1174179.mozfiles.com/files/1174179/navneet_kaur_gill_md.pdfIn PDF document text
    • https://cdn.sqhk.co/desiruzag/gigj5ic/24215139401.pdfIn PDF document text
    • https://site-1175549.mozfiles.com/files/1175549/duck_game_free.pdfIn PDF document text
    • https://site-1175246.mozfiles.com/files/1175246/call_of_fps_shooting_duty_counter_modern_warfare.pdfIn PDF document text
    • https://site-1168374.mozfiles.com/files/1168374/94876045036.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4454043/normal_5fd67d1960629.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4448124/normal_5fbd1ba2a0659.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4371023/normal_5fbd5f1f1d789.pdfIn PDF document text
    • http://www.ascendercorp.com/In PDF document text
    • http://www.ascendercorp.com/typedesigners.htmlIn 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_off0000d5eb.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xD5EB 5428 bytes
SHA-256: 80e101fc5e406ea9dd2d9516b7fdc84dc78aabdc6e57305b0648bd386a94a42d
font_01_sfnt_off0000e85d.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xE85D 10884 bytes
SHA-256: 60742dff2cffbc963f347eab0cfdf4707f143dc0d8d4a0d1cede7f3d8933380a

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