Malicious PDF — malware analysis report

Static analysis result for SHA-256 81b7a4fa620a57d3…

MALICIOUS

PDF

90.4 KB Created: 2021-07-02 11:25:09 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3)
MD5: 219597b108e57a041858e371c5804539 SHA-1: 95fc1c3311e70d88ba3ee3c35dd70d9fbdc3b2aa SHA-256: 81b7a4fa620a57d3d8ca81eee574585d0741a18fa5b9e50e7302465f79a7e1ca
156 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment

The file was detected as malicious by ClamAV and an ML classifier, indicating a high likelihood of malicious intent. It contains numerous URLs that form a link farm, likely intended to redirect users to phishing or scam websites. The presence of PDF_SEO_DISPOSABLE_LINK_FARM and PDF_COMPROMISED_CMS_UPLOAD_LINK_FARM heuristics further supports this, suggesting the use of compromised or disposable hosting for malicious redirection. No scripts were extracted, but the PDF structure itself facilitates the attack.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9835

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
  • PDF link farm points to compromised-WordPress upload storage medium PDF_COMPROMISED_CMS_UPLOAD_LINK_FARM
    PDF contains multiple clickable links, across many distinct hosts, whose targets are random-slug files parked in the upload directories of vulnerable WordPress form plugins (FormCraft, Super Forms). This is the hallmark of the 'free document/template' SEO phishing PDF family, which ranks for search queries and routes users into payload/redirect chains hosted on compromised sites. The PDF itself carries no exploit — the risk is the linked destinations.
  • 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://synerhu.ru/uplcv?utm_term=seed+treatment+with+biofertilizers+pdf
    • http://vasilii-orlov.fun/wp-content/plugins/super-forms/uploads/php/files/3923d8a3a0f94ee59d00c7b68ed9a9e9/56947620361.pdf
    • https://organicfertilizerproduction.com/d/files/82139759324.pdf
    • https://expobar.vn/app/webroot/files/images/pages/files/dokexomafif.pdf
    • https://rebates.forex/wp-content/plugins/super-forms/uploads/php/files/qfb3maed92u930dvrnp5ig7bo4/83711986712.pdf
    • http://iphysiology.ru/upload/46396064325.pdf
    • https://cortopolis.ar/userfiles/file/lemugoxovebofifupiput.pdf
    • http://pantryscan.com/123cars/imagefck/file/426826500.pdf
    • https://daleplumbinginc.com/wp-content/plugins/super-forms/uploads/php/files/b312fa8b76ab409dedc998a34c20aa57/tunokoxoxogamovimaneto.pdf
    • https://kachhiproperties.com/wp-content/plugins/super-forms/uploads/php/files/mp6vlhi82imbgss9tdb8fd6aq7/51824805332.pdf
    • https://a1-recruitment.fr/v2011/Files/fck_upload/file/talubod.pdf
    • http://aucoindeshalles.com/menu/file/73966373631.pdf
    • https://www.northamericatalk.com/wp-content/plugins/formcraft/file-upload/server/content/files/160a155f11b9a4---fuzafakisumiga.pdf
    • https://cananalimdar.com/wp-content/plugins/super-forms/uploads/php/files/fvn04a1u7324im7uvb6qnv5mt1/83985870698.pdf
    • http://www.justgiveahand.org/wp-content/plugins/formcraft/file-upload/server/content/files/160abe6f365df0---58879887609.pdf
    • https://georgiamusicpartners.org/wp-content/plugins/super-forms/uploads/php/files/5090cf353eed52b808dc54d80fbf953d/meduxarivolovokumosetal.pdf
    • http://www.cuerpomenteyespiritu.es/wp-content/plugins/formcraft/file-upload/server/content/files/160715302593ff---44992153237.pdf
    • https://www.physioaktivkramer.de/wp-content/plugins/formcraft/file-upload/server/content/files/160a8de32f0655---lidunizaposapowewal.pdf
    • http://fogathajtohirek.hu/fckfiles/file/56007267858.pdf
    • http://skuplaptop.pl/wp-content/plugins/formcraft/file-upload/server/content/files/160aec56261eb5---96536043365.pdf
    • http://www.sunarsurdurulebilir.com/wp-content/plugins/super-forms/uploads/php/files/20gnsd2m8lukseehqcdd5fkfj0/11817711269.pdf
    • https://canadiancontractorservices.com/wp-content/plugins/super-forms/uploads/php/files/lvrqsqq6k1ribn5dd7dgud9k24/sadunufep.pdf
    • http://sevoir.hu/uploads/file/12064914843.pdf
    • https://mosoptagro.ru/wp-content/plugins/super-forms/uploads/php/files/fa31f3f298ceec7282bd60f4b1ee73c8/ketuxarube.pdf
    • https://realestateconnect.biz/wp-content/plugins/super-forms/uploads/php/files/q0vvlhtt0nks23tv3mdp0jq1q3/vugasexaligoreniwebexasoz.pdf
    • http://www.eflox.net/wp-content/plugins/formcraft/file-upload/server/content/files/160ad4bcd01b09---6312721501.pdf
    • https://feriaesotericadeatocha.com/wp-content/plugins/formcraft/file-upload/server/content/files/1608116b71d2f4---xufiserimuxerezuvibu.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://dejavu.sourceforge.net
    • http://dejavu.sourceforge.net/wiki/index.php/License

Extracted artifacts 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
font_00_sfnt_off0000fcf9.bin
52e8f7d6022ad4fb7c6a6bb596285988f809cbf7669cf92a1a70ab78252eac3a
pdf-font-stream PDF embedded font (sfnt) at offset 0xFCF9 17476 bytes
font_01_sfnt_off00012a8b.bin
998a71617dd7222e570095a34eb5d09fbcdf4084768f188f31c3d14bb07f8376
pdf-font-stream PDF embedded font (sfnt) at offset 0x12A8B 11124 bytes
font_02_sfnt_off00014424.bin
9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1
pdf-font-stream PDF embedded font (sfnt) at offset 0x14424 16792 bytes