Malicious PDF — malware analysis report

Static analysis result for SHA-256 f8f49942442545bf…

MALICIOUS

PDF

69.2 KB Created: 2021-09-16 03:31:51 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-10-26
MD5: a3f40d5d5c62b6f823cad27d74804c2b SHA-1: a5e34688adc3a6d7d526c7d982f4318b349ec378 SHA-256: f8f49942442545bf37d9ccf43148f3560bb58ea4247c46d19c3e2deaf590f0ce
126 Risk Score

Malware Insights

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

The file was detected as malicious by ClamAV and an ML classifier, indicating a high likelihood of malicious intent. It contains numerous embedded URLs, many of which point to PDF files hosted on various domains, suggesting a link farm or redirection mechanism. The heuristic 'PDF_SEO_DISPOSABLE_LINK_FARM' specifically flags the sample as a link farm on disposable hosting, reinforcing the phishing or malware distribution lure. No scripts were extracted, but the presence of multiple external URIs and the link farm heuristic strongly suggest the PDF's purpose is to redirect the user to malicious content.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9993

Heuristics 5

  • ClamAV: Pdf.Phishing.Trojan-d2568dad23a94d95-d2568dad23a94d95-10044375-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Phishing.Trojan-d2568dad23a94d95-d2568dad23a94d95-10044375-0
  • 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://rubyyadav.com/nbloom/fckuploads/file/ripixukuloriteme.pdf In PDF document text
    • http://kite-surf.sk/files/potafunizovitoguligutok.pdfIn PDF document text
    • http://www.ibadirect.com/wp-content/plugins/formcraft/file-upload/server/content/files/161316a1bb06b8---51386581374.pdfIn PDF document text
    • https://ylwlgwadmin.ylwl.cn/upload/files/vupusugekeromuxojemuxak.pdfIn PDF document text
    • http://nemochem.cn/upload/files/jipij.pdfIn PDF document text
    • http://hoanggiaphatstone.com/upload/files/wuvuguzokanobojuvave.pdfIn PDF document text
    • http://22vek-omsk.ru/fck_editor_files/files/95645832771.pdfIn PDF document text
    • http://giaodantanthaison.com/Images_upload/files/kabiforodoxubejowewu.pdfIn PDF document text
    • https://skillmapmagazine.com/ckfinder/userfiles/files/gisagizo.pdfIn PDF document text
    • https://piphoto.tw/uploads/files/202109031927523844.pdfIn PDF document text
    • https://littleedupark.com/ckfinder/userfiles/files/18306102283.pdfIn PDF document text
    • http://fatimaartwork.com/userfiles/file/98321859933.pdfIn PDF document text
    • http://mouaumfb.com/wp-content/plugins/formcraft/file-upload/server/content/files/1614261e0a5f3e---puluzi.pdfIn PDF document text
    • https://betalinktech.com/blmedia/file/nodiz.pdfIn PDF document text
    • https://sasalidayanisma.org/uploads/file/23306047738.pdfIn PDF document text
    • https://adamant54.ru/userfiles/files/filimodiwodosenosit.pdfIn PDF document text
    • http://erodiertechnik-wenzel.de/userfiles/file/mutosobosurul.pdfIn PDF document text
    • https://feedproxy.google.com/~r/Uplcv/~3/1xuhb7AK25c/uplcv?utm_term=harmonic+sum+formulaPDF 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_off0000aeb2.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xAEB2 10360 bytes
SHA-256: 0f026772b0443fed8cd3e3124578b2e46b235d3878f6fb72148735f337f7c7ab
font_01_sfnt_off0000c5fc.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xC5FC 16216 bytes
SHA-256: 3224c703f5f29d73a842532e7dfd954a50bfb57b9703b3616d7e98781e9963de
font_02_sfnt_off0000f018.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xF018 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1

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