Malicious PDF — malware analysis report

Static analysis result for SHA-256 52e8b75adf86d938…

MALICIOUS

PDF

71.2 KB Created: 2021-06-04 09:01:46 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 4.8.7)
MD5: f1035c5d3b1e7d9ee04ffec20dde5e36 SHA-1: cc8d4934aaf51bc7e327b68c952c6f9638d7dfa5 SHA-256: 52e8b75adf86d93869633d25f0089c8df2759a98622e75bb2bc497aee9d85ed1
186 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1203 Exploitation for Client Execution

The PDF file was identified as malicious by ClamAV and an ML classifier, exhibiting characteristics of a link farm. It contains numerous external URIs, with a significant number pointing to disposable hosting services, suggesting an attempt to distribute malicious content or redirect users to phishing sites. The presence of a link farm indicates a broad distribution strategy, likely initiated via spearphishing.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9998

Heuristics 6

  • 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-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.
  • 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://cructi.ru/pbw?utm_term=spelling+rules+workbook+joanne+rudling+pdf
    • https://guvoxokogavi.weebly.com/uploads/1/3/4/3/134374443/6f10ed63.pdf
    • https://gigunomivu.weebly.com/uploads/1/3/0/9/130970016/d4ae1bc.pdf
    • https://cdn-cms.f-static.net/uploads/4421940/normal_6011b4554bb2e.pdf
    • https://static.s123-cdn-static.com/uploads/4450734/normal_5fdfcc0dc1af5.pdf
    • https://kobipisi.weebly.com/uploads/1/3/4/3/134312725/2185684.pdf
    • https://mebudowafiwene.weebly.com/uploads/1/3/4/6/134629245/lafufurakad_tanazudobigal_bapisa_kaxiki.pdf
    • https://vegivuben.weebly.com/uploads/1/3/4/6/134660922/83e28.pdf
    • https://cdn-cms.f-static.net/uploads/4444649/normal_60378c5560162.pdf
    • https://cdn-cms.f-static.net/uploads/4473375/normal_6058dc5183dcd.pdf
    • https://cdn-cms.f-static.net/uploads/4451350/normal_60156cd4049cb.pdf
    • http://www.ascendercorp.com/
    • http://www.ascendercorp.com/typedesigners.html
    • http://zewalar.pbworks.com/f/family_guy_the_quest_for_stuff_hack_ios.pdf
    • http://gosirata.pbworks.com/w/file/fetch/144443472/watch_hunger_games_mockingjay_-_part_1_online_free_-_123movies.pdf
    • http://pupowivala.pbworks.com/f/29577383576.pdf
    • http://lekipirunezi.pbworks.com/f/my_boy_emulator_apk_ios.pdf
    • http://vawaguzidatu.pbworks.com/w/file/fetch/144427227/77776924278.pdf
    • http://gijorugisaw.pbworks.com/f/the_nullification_crisis_worksheet_answers.pdf
    • http://gudikijuruf.pbworks.com/w/file/fetch/144600723/the_alchemist_characters_part_1_summary.pdf
    • http://pudamalulera.pbworks.com/f/sidurer.pdf
    • http://lopofemusun.pbworks.com/f/rogoluwibazu.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 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
font_00_sfnt_off0000d626.bin
16c604119b9ade348d1e6098946270bc40c1665903cb3eadd95577bdeb42fb58		 pdf-font-stream PDF embedded font (sfnt) at offset 0xD626 5684 bytes
font_01_sfnt_off0000e999.bin
ca8c59fc7ffc128e3c94be85e0baaf2e2a18799555f3971da7ebc35e5fa5311e		 pdf-font-stream PDF embedded font (sfnt) at offset 0xE999 11004 bytes

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