Ramnit PDF malware analysis — malicious · 527a61e931bb1aff

MALICIOUS

PDF

110.9 KB Created: 2014-02-08 15:10:28 +08:00 Authoring application: Canon

MD5: 2ac7ebba4e0bcd467df222cc31c45510 SHA-1: 589d81a9dabaff9dd2e6d4ca3fe9dd13826962d0 SHA-256: 527a61e931bb1aff99e83095b08ee304523b10d05e6ee9f2579928e1bb6c0028

214 Risk Score

Malware Insights

Ramnit · confidence 95%

MITRE ATT&CK

T1059.005 Visual Basic T1204.002 Malicious File T1105 Ingress Tool Transfer

The PDF contains embedded VBScript which reconstructs and executes a PE payload named 'svchost.exe'. This VBScript is responsible for dropping the PE file, indicating a downloader or dropper functionality. ClamAV detection confirms the presence of the Ramnit trojan. The ML classifier also strongly indicates maliciousness.

Machine Learning

Nyx PDF Classifier malicious score 0.9913

Heuristics 5

VBScript in PDF stream reconstructs and runs a PE payload critical PDF_VBS_HEX_PE_DROPPER

PDF stream contains an HTML/VBScript block that decodes a long hex string into a Windows executable and runs it via WScript.Shell. This is an embedded dropper payload, not ordinary PDF JavaScript.
ClamAV detection on extracted artifact critical EXTRACTED_FILE_CLAMAV

ClamAV flagged at least one file extracted from inside this sample. Even when the wrapping document carries no AV detection of its own, a hit on the carved artifact is a strong indicator the sample is a delivery vehicle.
Embedded script payload in PDF stream high PDF_EMBEDDED_SCRIPT_PAYLOAD

PDF stream bytes contain script execution markers such as ActiveXObject/CreateObject, WScript.Shell, PowerShell, or shell-exec primitives. This is stronger than ordinary PDF JavaScript because it indicates a staged external script payload hidden in stream bytes.
Suspicious extracted artifact medium 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.
PDF paints image(s) but contains no text operators info PDF_IMAGE_ONLY_LURE

PDF has 1 image XObject(s) and the content stream contains no text-emitting operators (BT/ET, Tj, TJ, ', ") in either raw bytes or decompressed streams — this is the screenshot-as-PDF pattern used to bypass text-based scanners and to deliver instructions purely through rendered pixels. It is informational unless paired with invisible links or risky URI context.

Extracted artifacts 2

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`embedded_vbs_dropper_0000019a.vbs` `50b36b292c4a29f5f0d9642bb1487d597e7f817cb538628ff0d791b00e4fac65`	pdf-embedded-script	PDF raw bytes VBScript dropper at offset 0x19A	113122 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 1 shell/COM execution token(s). Carved artifact contains 1 long base64-like blob(s).
`svchost.exe` `fd6c69c345f1e32924f0a5bb7393e191b393a78d58e2c6413b03ced7482f2320`	embedded-pe	Decoded PE from PDF VBScript dropper at offset 0x19A	56320 bytes
Detection ClamAV: Win.Trojan.Ramnit-9775455-0 Obfuscation or payload: likely Carved artifact entropy is 7.89, consistent with packed or encrypted content.

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