Malicious PDF — malware analysis report

Static analysis result for SHA-256 f1c4946d8dd734c6…

MALICIOUS

PDF

73.8 KB Created: 2021-03-28 02:16:00 +02:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 4.8.7)
MD5: 0b3cbbb835af04fd948531730de798ee SHA-1: e7c15f7537fe2910350123bcc9df8d3685d43174 SHA-256: f1c4946d8dd734c6e17905e099737907dca506256fce8dc501112fc9376343ce
156 Risk Score

Malware Insights

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

This PDF file was detected as malicious by ClamAV and an ML classifier. It contains a large number of external links, many pointing to other PDFs, suggesting a link farm or SEO manipulation tactic. One of the embedded URLs, 'https://zajinet.ru/strik?utm_term=reading+comprehension+worksheets', is likely the primary lure. No scripts were extracted, but the PDF structure itself is used to host numerous external links.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9997

Heuristics 5

  • Small PDF contains mass external PDF link farm critical PDF_SEO_LINK_FARM
    Small PDF contains many clickable external PDF links, mostly clustered on one host. This matches generated SEO/link-farm PDF carriers used to route users into malicious or unwanted-software delivery chains, rather than a normal document citation pattern.
  • ClamAV: Pdf.Phishing.Trojan-d2568dad23a94d95-d2568dad23a94d95-10044375-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Phishing.Trojan-d2568dad23a94d95-d2568dad23a94d95-10044375-0
  • 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://zajinet.ru/strik?utm_term=reading+comprehension+worksheets
    • https://cdn-cms.f-static.net/uploads/4443819/normal_605278bbcb6d6.pdf
    • https://static.s123-cdn-static.com/uploads/4373504/normal_5fefe4f3e8b9a.pdf
    • https://cdn-cms.f-static.net/uploads/4450042/normal_605a17d38e334.pdf
    • https://fovibera.weebly.com/uploads/1/3/5/3/135324383/5044794.pdf
    • https://nuxajitavira.weebly.com/uploads/1/3/1/8/131871558/1997212.pdf
    • https://radinake.weebly.com/uploads/1/3/1/8/131856095/tosunawuwogunuwadiv.pdf
    • https://jerolota.weebly.com/uploads/1/3/4/8/134859034/dfa2c83b6f.pdf
    • https://cdn-cms.f-static.net/uploads/4385011/normal_600e52dfbb430.pdf
    • https://cdn-cms.f-static.net/uploads/4366055/normal_5fe8e864841ec.pdf
    • https://segunimumise.weebly.com/uploads/1/3/1/0/131070895/3955769.pdf
    • https://vanufutalolu.weebly.com/uploads/1/3/1/1/131164160/bupijenofizetof_sitizadesu.pdf
    • https://dalulasu.weebly.com/uploads/1/3/4/4/134493325/9422837.pdf
    • https://static.s123-cdn-static.com/uploads/4393358/normal_5fc5a93ac2c03.pdf
    • https://dutukoviwu.weebly.com/uploads/1/3/0/8/130873875/2107392.pdf
    • https://cdn-cms.f-static.net/uploads/4485927/normal_600e2f6065172.pdf
    • https://static.s123-cdn-static.com/uploads/4485442/normal_5ff01affee64b.pdf
    • http://www.ascendercorp.com/
    • http://www.ascendercorp.com/typedesigners.html
    • https://s3.amazonaws.com/xipavir/duledurajil.pdf
    • https://s3.amazonaws.com/ponivotigegepub/form_utility_definition_business_studies.pdf
    • https://s3.amazonaws.com/rilexazejuzovep/tujagotomasepuwo.pdf
    • https://s3.amazonaws.com/tobovunoberiki/anet_a8_plus_marlin_firmware.pdf
    • https://s3.amazonaws.com/divelatoxa/vibedilozubemor.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 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
font_00_sfnt_off0000e1a3.bin
1b5a8666cd91e05f72bf4970ae06b74398544ceefcad681e92bc9dd105ef553e		 pdf-font-stream PDF embedded font (sfnt) at offset 0xE1A3 5616 bytes
font_01_sfnt_off0000f4aa.bin
9c3bf861e7bc7d2327d056c6f0fef3de727221ef79f82de339ce11ae9c52164a		 pdf-font-stream PDF embedded font (sfnt) at offset 0xF4AA 10932 bytes

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