RTF malware analysis — malicious · b9a8f9966308e9d4

MALICIOUS

RTF

998.0 KB First seen: 2021-05-23

MD5: c7f0223e378db394b8b5d08090d00019 SHA-1: b6a95a4ef9069a334d75ffb94a2a5abcbc71aad7 SHA-256: b9a8f9966308e9d45d68ad1ffa18bc00020a8a40f860b1e0fae6876c8f4bb680

242 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The RTF file contains multiple indicators of exploitation for CVE-2017-11882, a known vulnerability in Microsoft Equation Editor. The presence of OLE object data, automatic linking, and excessive hex-encoded data strongly suggests that the file is designed to deliver and execute a payload via this vulnerability. The extracted artifact 'objdata_00_off000000d3.bin' is likely the embedded payload.

Heuristics 7

Equation Editor activation — CVE-2017-11882 related high CVE related CVE_2017_11882_ACTIVATION_RELATED

RTF decodes to an Equation.3 ProgID and requests OLE activation with \objemb plus \objupdate. This reaches the legacy Equation Editor attack surface used by CVE-2017-11882/CVE-2018-0802 documents, but the malformed MTEF/native payload needed for stronger attribution was not recovered.
Split hex Equation Editor ProgID + OLE object critical RTF_EQUATION_EDITOR

RTF embeds the Equation.3 ProgID as hex bytes near OLE object activation and splits the byte stream with whitespace or an ignorable RTF group. This is an Equation Editor OLE activation surface commonly used by CVE-2017-11882 / CVE-2018-0802 exploit documents.
Automatically linked OLE object high RTF_OBJAUTLINK

RTF contains \objautlink — an automatically linked OLE object surface that can be updated or activated when Word opens the document.
\objupdate forces OLE activation high RTF_OBJUPDATE

RTF contains \objupdate — forces automatic OLE object instantiation when the document is opened, bypassing user interaction. Almost exclusively seen in Equation Editor exploit documents.
Large hex data blocks in OLE object high RTF_EXCESSIVE_HEX

RTF contains ~1021KB of hex-encoded data inside \objdata sections — may hide a payload
OLE object data medium RTF_OBJDATA

RTF contains 2 \objdata section(s) — embedded OLE objects
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.

Filename	Kind	Source	Size
`objdata_00_off000000d3.bin`	rtf-objdata-decoded	RTF \objdata at offset 0xD3	510751 bytes
SHA-256: `246ce9307982e318f6dc62a576e4fdb8566d6cb8edd52461dc39f76a536ff3dc`
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact entropy is 8.00, consistent with packed or encrypted content.

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