Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 f080b3ba979f8547…

MALICIOUS

RTF / .DOC

3.88 MB First seen: 2022-05-27
MD5: 0ecb6ed891d173443fa3654c31e14320 SHA-1: 6867f37817db501ce103813f791899f3cf1bc1e8 SHA-256: f080b3ba979f854761526f4bc6bd5b8210b48d5f91f15b1a1423849107775e11
382 Risk Score

Malware Insights

MITRE ATT&CK
T1204.002 Malicious File T1566.001 Spearphishing Attachment

The RTF document contains embedded OLE objects and utilizes the Equation Editor vulnerability (CVE-2017-11882) to execute arbitrary code. The presence of a PE header within hex-encoded data strongly suggests the embedded object is a payload. ClamAV detection as Rtf.Dropper.Agent-9965975-1 further confirms its malicious nature. The primary attack vector is likely a spearphishing attachment designed to exploit this known vulnerability.

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.
  • Composite Moniker in RTF OLE object high CVE related RTF_COMPOSITE_MONIKER_RELATED
    RTF contains Composite Moniker CLSID in OLE object context, but no nearby scriptlet/SCT payload was confirmed. Treat as related moniker attack-surface evidence rather than proof of CVE-2017-8570 exploitation.
  • 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
  • \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 ~2038KB 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.

FilenameKindSourceSize
objdata_00_off00001291.bin
69bbe63e59bbf7f4923b2a70735ee85bcc0ab649d8aafd89209e916f32a65587
rtf-objdata-decoded RTF \objdata at offset 0x1291 1037099 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact entropy is 7.77, consistent with packed or encrypted content.
objdata_01_off0020723c.bin
b5fb24d310a9bf9f48aea8e381ad105e2f4a64fcacf54516332e6d3acbd8cb23
rtf-objdata-decoded RTF \objdata at offset 0x20723C 462306 bytes