Malicious PDF — malware analysis report

Static analysis result for SHA-256 81c5fd3d88424528…

MALICIOUS

PDF

79.2 KB Created: 2021-09-17 16:56:41 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-10-24
MD5: 7e3ebdeb14c3279242257bb4598adfe7 SHA-1: 5e7513d8faddbc8137696f4f575fb778963062a1 SHA-256: 81c5fd3d88424528b576260e551ea0e9800dbc6060dfd80f79d8a035f0a4dd9e
194 Risk Score

Malware Insights

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

This PDF file exhibits multiple indicators of malicious activity, including malformed streams indicative of exploit code and a high ML classifier score. The presence of numerous embedded URLs, many pointing to disposable hosting and employing UTM parameters, suggests a link farm designed to redirect users to malicious content. The 'Payment redirection / bank-detail change lure' heuristic strongly indicates a business email compromise (BEC) or phishing attempt, aiming to trick users into altering payment instructions. While no scripts were explicitly extracted, the PDF structure and exploit indicators suggest it may leverage embedded JavaScript or other exploits to facilitate the download of a secondary payload.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9949

Heuristics 8

  • ClamAV: Pdf.Phishing.Trojan-d2568dad23a94d95-d2568dad23a94d95-10044375-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Phishing.Trojan-d2568dad23a94d95-d2568dad23a94d95-10044375-0
  • Payment redirection / bank-detail change lure high SE_PAYMENT_REDIRECT_LURE
    Document describes new or changed bank, wire, ACH, IBAN, SWIFT, or routing instructions — a high-value business-email-compromise pattern
  • Malformed active-content stream length medium PDF_MALFORMED_EXPLOIT_STREAM_LENGTH
    A PDF stream that carries active/exploit-looking content has a declared /Length that does not match the recovered stream body. Malformed stream boundaries and length mismatches are common parser-evasion/supporting evidence around Reader exploit streams.
  • 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.
  • Visual download / call-to-action button lure low SE_DOWNLOAD_BUTTON
    Document contains a call-to-action phrase ('Click here to download', 'Download Now', etc.) — low-signal unless other findings point to a malicious workflow
  • 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://crewmak.ru/uplcv?utm_term=how+to+send+large+video+files+from+android+to+android PDF link annotation
    • https://kcss.hu/korosi/userfiles/file/3019084186.pdfIn PDF document text
    • https://restaurant-kamkok.fr/img/Data/file/bomidaritad.pdfIn PDF document text
    • https://oferta.lt/i/File/77422963987.pdfIn PDF document text
    • http://maychebiengoduykhuong.com/media/ftp/file/23348768516.pdfIn PDF document text
    • http://89928386.com/uploads/files/202109162310443110.pdfIn PDF document text
    • http://elektron.be/public/userimgs/files/jovewamebed.pdfIn PDF document text
    • http://es-manzokudou.com/yamituki-n/uploads/files/5819210526.pdfIn PDF document text
    • http://fujieshubao.com/zk/UploadFile/file/2021091419170173499.pdfIn PDF document text
    • https://dmshospital.com/mm_engg/files/vunebo.pdfIn PDF document text
    • http://kaus21.com/userData/board/file/54794994374.pdfIn PDF document text
    • http://files.ibiza-ferien.de/file/vetulijezizagimejepej.pdfIn PDF document text
    • http://alphasigmaoverseas.com/userfiles/file/fidonidi.pdfIn PDF document text
    • http://www.physedu.in/newsite/userfiles/files/nalavirexogawexiwatavi.pdfIn PDF document text
    • http://bora.su/ckfinder/userfiles/files/8467719399.pdfIn PDF document text
    • http://abwcolley.com/uploads/files/webukix.pdfIn PDF document text
    • https://harpethvalleyhealth.com/wp-content/plugins/super-forms/uploads/php/files/9a4a935994c7e89fa74ead0275cacbd7/jumoxalelexerefewezotab.pdfIn PDF document text
    • http://extreamtuning.ru/wp-content/plugins/formcraft/file-upload/server/content/files/1613cbe0019348---34447546779.pdfIn PDF document text
    • http://americasbestwingsbeltsville.com/uploads/files/69765637453.pdfIn PDF document text
    • http://braghieriarchitettura.com/userfiles/files/kapewiranibuki.pdfIn PDF document text
    • https://olgunbey.com/upload/ckfinder/files/gijizirapeg.pdfIn PDF document text
    • https://infotechsystemsonline.com/ital/www/img/file/12931688580.pdfIn PDF document text
    • https://chorland-dining.com/webroot/editor-uploads/files/kuvofu.pdfIn PDF document text
    • https://hoanghaie.com/Images_upload/files/kugosabol.pdfIn PDF document text
    • https://npkfertilizerproduction.com/d/files/nulapibapo.pdfIn PDF document text
    • http://cu-hinothai.com/ckfinder/userfiles/files/ximelo.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://dejavu.sourceforge.netIn PDF document text
    • http://dejavu.sourceforge.net/wiki/index.php/LicenseIn PDF document text

Extracted artifacts 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
font_00_sfnt_off0000d026.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xD026 17872 bytes
SHA-256: dbad75a5b270f8959c919b535e8428671b84f51bd94f12d1c1b3442675c9421e
font_01_sfnt_off0000fe4b.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xFE4B 10840 bytes
SHA-256: 305a52f9d3f088bde89a01d41529c8176695299eea021fc941f22fcfe7f577f4
font_02_sfnt_off00011720.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x11720 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1

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