Malicious PDF — malware analysis report

Static analysis result for SHA-256 850f9f396f0c28bb…

MALICIOUS

PDF

83.2 KB Created: 2021-04-06 17:45:11 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 4.8.7)
MD5: 097aaa39394572a1a96f73cfad2adb3f SHA-1: aa22b66e53ddecd5a4a42211d4ba084b2cdcbbcc SHA-256: 850f9f396f0c28bbb1912a2431242c40c09913dba37d50df46aad8193b196edd
196 Risk Score

Malware Insights

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

The PDF contains numerous external links, with one pointing to a suspicious domain ('jacksth.ru') flagged by heuristics as a potential link farm. ClamAV detection and ML classification strongly indicate maliciousness, specifically identifying it as a phishing trojan. The heuristic 'SE_PASSWORD_ARCHIVE_LURE' suggests a common tactic of using password-protected archives to bypass initial security scans, implying this PDF is a step in a larger malware delivery chain.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9998

Heuristics 6

  • 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
  • Password-protected archive handoff high SE_PASSWORD_ARCHIVE_LURE
    Document gives password instructions for an archive or attachment — often used to keep payloads encrypted until after gateway scanning
  • 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://jacksth.ru/strik?utm_term=divaldo+franco+melhores+livros
    • https://static.s123-cdn-static.com/uploads/4460688/normal_60011cefad86c.pdf
    • https://cdn-cms.f-static.net/uploads/4451574/normal_6062339718944.pdf
    • https://cdn-cms.f-static.net/uploads/4417656/normal_605fb52810d77.pdf
    • http://hayatevesigar.online/handwriting_worksheet_for_1st_gradepg2qr.pdf
    • https://cdn-cms.f-static.net/uploads/4487662/normal_604a4acdb982c.pdf
    • https://cdn-cms.f-static.net/uploads/4392193/normal_60526e4b3d3d0.pdf
    • https://cdn-cms.f-static.net/uploads/4370055/normal_5fd7a092808c5.pdf
    • https://cdn-cms.f-static.net/uploads/4420599/normal_5fd7d8c2200a7.pdf
    • http://babysampler.com/998870027pfdin.pdf
    • https://cdn-cms.f-static.net/uploads/4471723/normal_605cfa7ca1a39.pdf
    • https://cdn-cms.f-static.net/uploads/4405907/normal_6048906db14f4.pdf
    • http://www.ascendercorp.com/
    • http://www.ascendercorp.com/typedesigners.html
    • https://uploads.strikinglycdn.com/files/a3f27dc8-a3f9-46b6-acee-114fa52b1fd6/81729742173.pdf
    • https://uploads.strikinglycdn.com/files/67560383-9644-4630-ab8c-d7e657b85d57/moto_g_3rd_gen_price_in_pakistan_olx.pdf
    • https://1fc3e790-19e1-43b7-bae7-d09a953f51fe.filesusr.com/ugd/2c608b_acfe9259ed1a4f459c7a52c5b530dc08.pdf?index=true
    • https://dcc20dec-0195-4543-b617-cfb82efd15f0.filesusr.com/ugd/30ea26_453e6cabe52e42439b6be2cbe3e866cf.pdf?index=true
    • https://uploads.strikinglycdn.com/files/34acd1e6-443f-4b79-86c5-64b11a17eadd/xbox_360_failed_to_connect_to_xbox_live.pdf
    • https://s3.amazonaws.com/vabedafozo/79056302457.pdf
    • https://91ca87c2-c493-4616-adaa-fbcec45394e1.filesusr.com/ugd/6116da_e13421ed6324454d9f013ac80cc815bf.pdf?index=true
    • https://s3.amazonaws.com/voxipanovigepiv/cheetah_keyboard_old_version.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_off000101cb.bin
2ff836c54d27e994badfb56640201193e68b6a9b8e989fc2ec2da022d21f5ced		 pdf-font-stream PDF embedded font (sfnt) at offset 0x101CB 5320 bytes
font_01_sfnt_off000113c6.bin
2335813552426b133a191d3ae5e6ca5297c7d58fd5798f2e1fb4095183b6b807		 pdf-font-stream PDF embedded font (sfnt) at offset 0x113C6 14572 bytes

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