Malicious PDF — malware analysis report

Static analysis result for SHA-256 a5ff9ec0c4ba7822…

MALICIOUS

PDF

84.3 KB Created: 2021-04-25 20:41:54 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 4.8.7)
MD5: 584e491b3dd27a622c7c3c2e4962ff63 SHA-1: 330022ac1ffead91170b313aca0fee308379b7f4 SHA-256: a5ff9ec0c4ba78220b7d82400394c40422a2b8d47c8c8f44ae7f12e6e8e65fde
126 Risk Score

Malware Insights

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

The sample is a PDF file flagged by ClamAV as Pdf.Phishing.Trojan and a machine learning classifier as malicious. It contains numerous external URIs, many hosted on disposable domains, suggesting a link farm or phishing lure. The document body, though heavily obfuscated, contains references to wkhtmltopdf and creation dates, indicating it was likely generated programmatically. The presence of multiple suspicious URLs points towards an attempt to redirect the user to malicious content.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9995

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
  • 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://nipisod.ru/strik?utm_term=how+to+learn+a+piano+song+by+ear
    • http://dalnoboyi.xyz/irregular_verbs_spanish_meaningpm5o7.pdf
    • http://totalcreditcheck.info/is_2.9_gpa_good_for_law_school7tiux.pdf
    • http://biomaniks.website/what_courses_do_you_need_to_be_a_vet_teche940t.pdf
    • http://mestikon.online/bilenujexewamewosupilanum7izez.pdf
    • http://acupofjacob.com/carbonyl_reactioncpmq0.pdf
    • http://verapubudal.22web.org/apocalypse_meltdown_espaol.pdf
    • http://wordwild-store.com/85797316079ajgeb.pdf
    • http://nukels.xyz/pudigakokano078oc.pdf
    • http://espacecmb.xyz/vuwupavorememidusobasowol5q21l.pdf
    • http://xaxikobovivo.22web.org/peripheral_arteriovenous_malformations_embolization.pdf
    • http://arfeshome.com/the_hollow_restaurant_franklin_wv_menuenmvk.pdf
    • http://www.ascendercorp.com/
    • http://www.ascendercorp.com/typedesigners.html
    • http://www.daltonmaag.com/
    • https://d7ae471b-a447-437d-81b4-4e603f8679d9.filesusr.com/ugd/0a3240_09372d4e493240a4a2f5b5d07491a52d.pdf?index=true
    • http://dulubuli.rf.gd/birdland_sheet_music_bass.pdf
    • https://s3.amazonaws.com/lixuduwonifa/google_docs_template_design.pdf
    • https://s3.amazonaws.com/sepovutapakogaf/how_long_to_learn_algebra_2.pdf
    • http://burupopevetu.rf.gd/integrative_approaches_to_psychology_and_christianity_entwistle.pdf
    • http://rilulavonepuv.epizy.com/13610452703.pdf
    • https://a0e9597c-cfbb-4fc1-b0e0-47ed6411b148.filesusr.com/ugd/24269e_bc028ba6cac54327b07fbffd54ec1fdf.pdf?index=true
    • http://popadugabi.rf.gd/69852872693.pdf
    • http://zifenefumob.rf.gd/39772379823.pdf
    • http://tupudenijusab.rf.gd/96029417149.pdf
    • https://s3.amazonaws.com/zizene/sodoregamarovalodonuge.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 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
font_00_sfnt_off0000fcf7.bin
a21edd8dfedacf8096de11ee3843a21c7998ef3b5d64305c0f6b5b9c091250c1
pdf-font-stream PDF embedded font (sfnt) at offset 0xFCF7 5068 bytes
font_01_sfnt_off00010e48.bin
faeb77e0d7c2aa542d55fe1cf9189664270a98ae1498ac62780017ad68f54740
pdf-font-stream PDF embedded font (sfnt) at offset 0x10E48 11896 bytes
font_02_sfnt_off0001359c.bin
0d0f64e27578eb124b8bc81c7eceacdd166e22eddd95c81328e9fbd7de2a6333
pdf-font-stream PDF embedded font (sfnt) at offset 0x1359C 4324 bytes