Malicious PDF — malware analysis report

Static analysis result for SHA-256 a4a831f73b4cb724…

MALICIOUS

PDF

71.6 KB Created: 2021-02-13 17:01:18 +02:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 4.8.7) First seen: 2021-05-22
MD5: f59e59477cd85b563c138fecc53811e6 SHA-1: 847f17948c6fbd0dbd317dd974e30357cbe40e7f SHA-256: a4a831f73b4cb724745ade2b688d344b19eb0df22e8475ca1363532270c46856
184 Risk Score

Malware Insights

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

The PDF contains multiple embedded links pointing to known malicious redirector infrastructure and disposable hosting, as indicated by the PDF_MALICIOUS_REDIRECTOR_LINK and PDF_SEO_DISPOSABLE_LINK_FARM heuristics. The ML classifier and ClamAV also flagged this file as malicious, specifically as a phishing trojan. The document body, though heavily obfuscated, appears to be a lure related to educational worksheets, likely intended to trick users into clicking the malicious links.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9998

Heuristics 5

  • ClamAV: Pdf.Phishing.Trojan-d2528dad23a95d95-d2528dad23a95d95-10044376-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Phishing.Trojan-d2528dad23a95d95-d2528dad23a95d95-10044376-0
  • PDF links to known malicious redirector infrastructure critical PDF_MALICIOUS_REDIRECTOR_LINK
    PDF contains a clickable URI to redirector infrastructure used by a known malicious PDF SEO/adware delivery campaign. These documents typically rely on user interaction and redirect chains rather than a PDF parser vulnerability.
  • 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.
  • 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://yafferge.ru/wix?keyword=linear+inequalities+in+one+variable+worksheet In PDF document text
    • https://static.s123-cdn-static.com/uploads/4372982/normal_5fcea6e45989b.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4448992/normal_5fda6c1ee282e.pdfIn PDF document text
    • http://pakisonuzaruwav.iblogger.org/anbanavan_asaradhavan_adangadhavan_full_movie_tamil.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4404520/normal_5fe615ef68cf9.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4474989/normal_6024588d703f1.pdfIn PDF document text
    • http://geesecam.com/puxofetitolabifocm571.pdfIn PDF document text
    • http://businessmentality.com/6594257242344be1.pdfIn PDF document text
    • https://static.s123-cdn-static.com/uploads/4485329/normal_5ff134cdee918.pdfIn PDF document text
    • http://apparentlyopt.com/beautiful_in_white_piano_sheetzzjpj.pdfIn PDF document text
    • http://zunejabilake.22web.org/13542002628.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4405197/normal_600a9a045b258.pdfIn PDF document text
    • http://teplotronic.ru/email_template_to_inquiry_about_a_jobcvlc2.pdfIn PDF document text
    • https://cdn.sqhk.co/wujukipako/a8icoid/warlings_armageddon_hack_apk_android_1.pdfIn PDF document text
    • http://jsexj.fun/zupasuqixo.pdfIn PDF document text
    • http://www.ascendercorp.com/In PDF document text
    • http://www.ascendercorp.com/typedesigners.htmlIn PDF document text
    • http://rukinemofe.rf.gd/voot_app_colors_tv_naagin_3.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_off0000d9e6.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xD9E6 5196 bytes
SHA-256: 98533af6e39ec50c8e7bba36cd29b0b92d0230069b08a6399f7c8947a0e65649
font_01_sfnt_off0000eba8.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xEBA8 10980 bytes
SHA-256: 21493faf835d70655f837a357a40c597f0bede35fed53f38a3e6d5745bf4412b

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