Malicious PDF — malware analysis report

Static analysis result for SHA-256 be44387d5526a1d0…

MALICIOUS

PDF

99.3 KB Created: 2021-09-05 10:06:04 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-10-23
MD5: 3a6ab09602b82e4ce7d57fbe406b2a93 SHA-1: 546c8fe65dbd0fd0c54184323667b07f896d0738 SHA-256: be44387d5526a1d07b91c297f7e07665d71f1b699b44b35f2aadb65dc0fb27b4
156 Risk Score

Malware Insights

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

The PDF was flagged by ClamAV as Pdf.Phishing.Trojan and an ML classifier indicated a high probability of maliciousness. Multiple heuristics identified the document as a link farm, with many URLs pointing to compromised WordPress upload directories and disposable hosting. The document body is heavily obfuscated and appears to be generated by wkhtmltopdf, suggesting it's not intended for direct user reading but rather to host links.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9964

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://frontiersneurophotonics.org/wp-content/plugins/formcraft/file-upload/server/content/files/1/16093a26b5695c---60385227956.pdf In PDF document text
    • https://www.alpha-dynamics.gr/wp-content/plugins/formcraft/file-upload/server/content/files/160b110bd0af27---gidevixonejedavuv.pdfIn PDF document text
    • http://krcatikyonetimi.com/userfiles/file/27657200201.pdfIn PDF document text
    • http://cosyromania.com/media/file/sevowumujigarebuzaf.pdfIn PDF document text
    • http://naturallabs.fr/userfiles/file/3451680144.pdfIn PDF document text
    • http://penoplex24.ru/wp-content/plugins/formcraft/file-upload/server/content/files/160adc3c3bec9d---fufoki.pdfIn PDF document text
    • https://www.alphaveneers.com/wp-content/plugins/super-forms/uploads/php/files/e6feb6d74a9f6401975ea5393db9d28d/febugizutotuxakajexewu.pdfIn PDF document text
    • https://amblamy.ee/upload/file/1237801445.pdfIn PDF document text
    • http://bon-mar.com/fck_user_files/file/furukuzujavupagelajuw.pdfIn PDF document text
    • http://emannsltd.com/userfiles/pejinegunudopiga.pdfIn PDF document text
    • http://mbjarrahi.com/UploadedFiles/New/file/71663992080.pdfIn PDF document text
    • https://upbfassadenbau.com/upload/file/68425820591.pdfIn PDF document text
    • http://parvazyab.net/basefile/api203/files/kutedodixa.pdfIn PDF document text
    • http://remont-elektro.eu/archiv/file/mominevubamujoder.pdfIn PDF document text
    • https://daluxerealty.com/wp-content/plugins/super-forms/uploads/php/files/aa9060dsedbbol8464jm7vn424/20451258201.pdfIn PDF document text
    • http://xn--vb0b83rba554gca.kr/page_data/file/20210509195114.pdfIn PDF document text
    • http://martonelektro.hu/files/file/zajelerusofotafazedimom.pdfIn PDF document text
    • https://fortlauderdale-carservice.com/wp-content/plugins/formcraft/file-upload/server/content/files/161295ab092d9e---tenaseli.pdfIn PDF document text
    • http://phillipwhiting.com/wp-content/plugins/formcraft/file-upload/server/content/files/160e53722004a9---33969082514.pdfIn PDF document text
    • https://acethamessecurity.co.uk/wp-content/plugins/super-forms/uploads/php/files/e90d740d415924677086f2316fac3827/42291121274.pdfIn PDF document text
    • http://www.immiflex.com/wp-content/plugins/formcraft/file-upload/server/content/files/160735f7c254de---tekalasudukapisaja.pdfIn PDF document text
    • https://www.gml.de/wp-content/plugins/formcraft/file-upload/server/content/files/16085d9e9f240c---69071383640.pdfIn PDF document text
    • https://bataretak.com/img/files/file/18140958827.pdfIn PDF document text
    • https://homini.eu/wp-content/plugins/formcraft/file-upload/server/content/files/160a305e317d9c---sabatoruradufinuwowalig.pdfIn PDF document text
    • https://c4ir.ae/wp-content/plugins/super-forms/uploads/php/files/ibqhh0nba2tdk2c5207qdgked7/kasawutisisuwise.pdfIn PDF document text
    • https://feedproxy.google.com/~r/Uplcv/~3/3vuEKuznOb8/uplcv?utm_term=nutrition+et+hypertension+art%C3%A9rielle+pdfPDF link annotation
    • 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_off0001142a.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x1142A 22032 bytes
SHA-256: c8327a1d556e05d996cbb8c4d52cfcae4680e69f62d0e7816719070339696467
font_01_sfnt_off00014bc1.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x14BC1 10940 bytes
SHA-256: b14b3b5b7e4b5573d684e365b30ade3c27509a80f8b0c4ecb4cca144c27158a0
font_02_sfnt_off000164c0.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x164C0 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1

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