Malicious RTF — malware analysis report

Static analysis result for SHA-256 82fb252522cdae2a…

MALICIOUS

RTF

359.6 KB First seen: 2021-05-23
MD5: 3aede3db7e654977cb5d5cd06868c7d3 SHA-1: 5695c9d7656bf8467c5abc3963200c5664c7c245 SHA-256: 82fb252522cdae2a54e364c18a455aa74487f21b0b7f8292266d82fab7586083
340 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1203 Exploitation for Client Execution

The RTF document contains multiple indicators of exploitation, specifically related to CVE-2017-8570 and CVE-2017-0199/CVE-2017-8759, which are used to automatically download and execute a second-stage payload. The document body explicitly instructs the user to 'click Enable Editing', a common lure to bypass security measures and facilitate the execution of embedded malicious content. The embedded OLE objects and objdata sections are the likely carriers of the exploit and payload.

Heuristics 9

  • Composite Moniker — CVE-2017-8570 (drops SCT script) critical CVE related CVE_2017_8570
    RTF \objdata decodes to OLE data containing the Composite Moniker — CVE-2017-8570 (drops SCT script) CLSID — the vulnerable control/moniker is embedded directly in the document's object stream, the delivery shape of this exploit. RTF objects auto-render when Word opens the file.
  • CVE-2017-0199 / CVE-2017-8759 (OLE2Link auto-activated remote loader) critical CVE related RTF_OLE2LINK_REMOTE_MONIKER_LOADER
    RTF embeds an OLE2Link object that is force-activated with \objupdate (no user interaction on open) and fetches a remote second stage — through an INCLUDETEXT/INCLUDEPICTURE field or the OLE object's own moniker. This is the OLE2Link auto-update attack path shared by CVE-2017-0199 (server returns an HTA/scriptlet) and CVE-2017-8759 (server returns a SOAP WSDL the .NET parser compiles). Office processes the fetched response through the same code path; the specific CVE depends on the now-unreachable server content type.
  • 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.
  • 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.
  • Suspicious extracted artifact high 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.
  • OLE object data medium RTF_OBJDATA
    RTF contains 4 \objdata section(s) — embedded OLE objects
  • Embedded OLE object medium RTF_OBJEMB
    RTF contains \objemb — embedded OLE object
  • Macro/content-enable lure medium SE_ENABLE_LURE
    Document instructs the user to enable macros or editing — a common technique used by malware droppers to bypass Office macro security settings
🗂 Part of campaign: shared payload 3cd3b7d42e 51 samples

Extracted artifacts 4

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00000965.bin rtf-objdata-decoded RTF \objdata at offset 0x965 72049 bytes
SHA-256: 2ff80ab47bdaf1f99c44c92ac8d009de609f1af2a59161bfc7f0858ea6da4c68
objdata_01_off00007114.bin rtf-objdata-decoded RTF \objdata at offset 0x7114 72022 bytes
SHA-256: 31a1eebcd5a3c4911159287f9dd27de5c7714f8c2797fb82175af510279cc17a
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Static shellcode analysis recovered command string(s): WScript.Shell"")")
objdata_02_off0002bae3.bin rtf-objdata-decoded RTF \objdata at offset 0x2BAE3 2632 bytes
SHA-256: 1168a119c26543fbaa6e9ad1f2c0221f803fb28859c4a42b2857ff6b316de929
objdata_03_off0002d086.bin rtf-objdata-decoded RTF \objdata at offset 0x2D086 12297 bytes
SHA-256: e8d4fe950caed6dcfde26f4b616825bbe11b93458425974b7d075167f675abf7