RTF malware analysis — malicious · 551bf83fe92b8890

MALICIOUS

RTF

525.3 KB First seen: 2020-09-07

MD5: 34bd282f785eef2784154bab0e883bf8 SHA-1: 7159d4144b9dc368002bfe1acfe7bc0ce9844cb1 SHA-256: 551bf83fe92b8890a539f720f43c7749e48a4e3d6cc7a2bb4249242526271021

182 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution T1566.001 Phishing: Spearphishing Attachment

The RTF file contains embedded OLE object data, specifically related to Microsoft Equation Editor. Heuristics indicate a critical vulnerability (CVE-2017-11882) was exploited, which is a common method for delivering malicious payloads. The embedded artifact 'objdata_00_off00000043.bin' is the likely second-stage payload.

Heuristics 5

Decoded Equation Editor payload + PE critical CVE likely RTF_EQUATION_EDITOR

RTF decodes to an Equation Editor ProgID adjacent to OLE activation and the same decoded object stream contains embedded PE bytes. This matches the Equation Editor exploit surface used by CVE-2017-11882 / CVE-2018-0802 documents, while requiring payload evidence to avoid flagging benign Equation references.
Equation Editor OLE1 native payload — CVE-2017-11882 related critical CVE related CVE_2017_11882_RELATED

RTF decodes to an OLE1 Equation.3 embedded object whose native data is large and payload-like, and \objupdate requests automatic activation. This is the delivery shape used by Equation Editor RCE documents such as CVE-2017-11882/CVE-2018-0802, but the malformed MTEF record needed for exact attribution was not recovered.
\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.
OLE object data medium RTF_OBJDATA

RTF contains 1 \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_off00000043.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x43	227082 bytes
SHA-256: `12a95d2810a906182745dc9449e2400b23f443d4f3054778e159b0d8121e7239`
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact entropy is 7.94, consistent with packed or encrypted content.

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