Malicious PDF — malware analysis report

Static analysis result for SHA-256 bca4d3dd960e843b…

MALICIOUS

PDF

203.2 KB Created: 2012-03-30 14:29:13 +08:00
MD5: a5ddae333c123ad594e14974da0d4323 SHA-1: 6d7652f3c5bd8cb2dd8f0220e9e6f5880d26d2bb SHA-256: bca4d3dd960e843b6ba19fa63677b392dcc5571c2677d5edf868dd66c942e231
136 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell T1204.002 Malicious File T1566.002 Spearphishing Attachment

The PDF contains embedded JavaScript, indicated by multiple heuristic firings including PDF_JAVASCRIPT, PDF_JS, and PDF_EVAL. The ML classifier also flagged this PDF as malicious. The embedded JavaScript stream, stream_002_off000003a1.js, is the primary indicator of malicious activity. While the exact behavior of the script is not fully discernible due to obfuscation, its presence within a PDF and the ML classification strongly suggest it's designed to download and execute a secondary payload, a common technique for initial access.

Machine Learning

  • Nyx PDF Classifier malicious score 0.8535

Heuristics 7

  • RichMedia (Flash) high PDF_RICHMEDIA
    PDF contains /RichMedia (Adobe Flash) which is a historic exploit vector (matched inside decoded stream)
  • eval() call high PDF_EVAL
    eval() found — commonly used for obfuscated exploit execution (matched inside decoded stream)
  • JavaScript action low PDF_JAVASCRIPT
    PDF contains a /JavaScript action. Generic JavaScript is common in benign forms; specific dangerous APIs are scored by separate rules. (matched inside decoded stream)
  • Embedded JS stream low PDF_JS
    PDF references a /JS stream. Generic JavaScript is common in benign forms; specific dangerous APIs are scored by separate rules. (matched inside decoded stream)
  • Embedded file low PDF_EMBEDDED
    PDF embeds a file attachment — could carry an executable or another weaponised document as a nested payload (matched inside decoded stream)
  • Suspicious extracted artifact info EXTRACTED_FILE_STATIC_TRIAGE
    One or more files extracted from inside this sample matched static suspicious-content checks such as script obfuscation, encoded payload blobs, packed data, or execution/download terms.
  • 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 http://www.w3.org/1999/02/22-rdf-syntax-ns#
    • http://ns.adobe.com/xap/1.0/
    • http://purl.org/dc/elements/1.1/
    • http://ns.adobe.com/xap/1.0/mm/
    • http://ns.adobe.com/pdf/1.3/

Extracted artifacts 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
stream_002_off000003a1.js
b033562fbd6de4a813a100e21191f7f95176e58b2ae0b23feeb0dd749c9136e2		 decompressed-pdf-stream PDF FlateDecoded stream at offset 0x3A1 7123 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 1 eval/decoder/string-building token(s).
stream_009_off00001dcb.bin
4e56f0aafe9b1a1952829b6a9ad7a1ddc6dca0701b075b2ae945f11108af1bbe		 decompressed-pdf-stream PDF FlateDecoded stream at offset 0x1DCB 1929 bytes
objstm_0031_00.bin
19f2f89694ce926a721a42df90dd2b6cc9a1b3dbb55c2637d480842eaa1f3203		 pdf-objstm-decoded PDF /ObjStm 31 0 obj (inflated) 1746 bytes

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