RTF malware analysis — malicious · 5b58c2f68732b280

MALICIOUS

RTF

1.30 MB First seen: 2020-09-15

MD5: ad25d22457b9d159d06cdff453571039 SHA-1: 16c74643a7311d0e001122828203e856efae16e1 SHA-256: 5b58c2f68732b2801793bd78f74524449ae7c87ae3d14231780a794cc537cd5a

300 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The RTF file contains embedded OLE object data, specifically related to Equation Editor, and triggers critical heuristics for CVE-2017-11882. This indicates the file is designed to exploit this vulnerability for client-side execution. The presence of a high-entropy, PE-like artifact suggests it's a dropper for a secondary payload.

Heuristics 7

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.
ClamAV: Rtf.Dropper.Agent-9106590-0 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Rtf.Dropper.Agent-9106590-0
\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 ~1357KB of hex-encoded data inside \objdata sections — may hide a payload
OLE object data medium RTF_OBJDATA

RTF contains 1 \objdata section(s) — embedded OLE objects
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.

Extracted artifacts 1

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`objdata_00_off00000441.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x441	678994 bytes
SHA-256: `8e2c2c354a562d7f013802ab1b90a3a2d6e6e219944f2a9619ea7be811c53957`
Detection ClamAV: No threats found Obfuscation or payload: likely Static shellcode analysis found candidate code region(s). Indicators: SC_GETPC_CALL Carved artifact entropy is 7.99, consistent with packed or encrypted content.

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