RTF malware analysis — malicious · ba6e13c22a82d4a3

MALICIOUS

RTF

3.17 MB First seen: 2022-07-28

MD5: e974287c919140df4f3ba7b2ff4a0dde SHA-1: e8cf543bc13320829e8b23cb360992eaa0d3530a SHA-256: ba6e13c22a82d4a3171618908a787b15ed6f6b978cae89c9864cc3a5c8c01203

402 Risk Score

Malware Insights

MITRE ATT&CK

T1204 Malicious File Execution T1204.002 Malicious File Execution: Malicious File T1566 Phishing T1566.001 Phishing: Spearphishing Attachment T1059 Command and Scripting Interpreter T1059.003 Command and Scripting Interpreter: Windows Command Shell

The RTF document contains multiple indicators of exploitation for CVE-2017-11882, including an embedded Equation Editor object and associated OLE data. ClamAV detections confirm this is a dropper, with one signature identifying it as Rtf.Dropper.Agent-9965975-1 and another signature on an extracted artifact as Win.Trojan.AsyncRAT-9914220-0. The large amount of hex-encoded data within the OLE object likely hides the second-stage payload.

Heuristics 10

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.
PE header (with DOS stub) in hex data critical RTF_MZ_HEX

Hex-encoded PE (MZ + DOS stub) found inside RTF — likely an embedded executable payload
ClamAV: Rtf.Dropper.Agent-9965975-1 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Rtf.Dropper.Agent-9965975-1
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.
\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 ~1774KB 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
Embedded OLE object medium RTF_OBJEMB

RTF contains \objemb — embedded OLE object
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 2

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`objdata_00_off000012ab.bin` `2d5b98363167f98bb417e54fa11a445ec9835777173b0a70f957161f469cfaf0`	rtf-objdata-decoded	RTF \objdata at offset 0x12AB	905003 bytes
Detection ClamAV: Win.Trojan.AsyncRAT-9914220-0 Obfuscation or payload: likely Carved artifact entropy is 7.93, consistent with packed or encrypted content.
`objdata_01_off001c6a70.bin` `a9ff9a80fcbe35345bbc4e4eca2212ef4c041b9f9a7826aafeaaa45782edf0a1`	rtf-objdata-decoded	RTF \objdata at offset 0x1C6A70	346904 bytes

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