Rtf.Dropper.Agent-6965878-0 — RTF malware analysis

Static analysis result for SHA-256 5e7663f662cedcc2…

MALICIOUS

RTF

320.4 KB Created: 2019-05-06 23:04:00 Authoring application: Microsoft Word 11.0.5604 First seen: 2019-08-04
MD5: f0424ed16b435f0c7c802f3a17cbd9de SHA-1: b32251aa7d08718774c8fc30af698de8cfebf142 SHA-256: 5e7663f662cedcc2c520b88928824a4c7caf5a6833f77cdb0051328d74ace1c8
340 Risk Score

Malware Insights

Rtf.Dropper.Agent-6965878-0 · confidence 95%

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

The file is an RTF document that contains multiple indicators of exploitation targeting Microsoft Equation Editor, specifically CVE-2017-11882 and CVE-2018-0798. These vulnerabilities are known to be used to execute arbitrary code, suggesting the document's primary purpose is to act as a dropper for a secondary malicious payload. The ClamAV detection name further supports this assessment.

Heuristics 8

  • Equation Editor CLSID critical CVE likely RTF_EQUATION_EDITOR
    Equation Editor OLE CLSID found inside an OLE object — exploited by CVE-2017-11882 / CVE-2018-0802 / CVE-2018-0798
  • CVE-2018-0798 — Equation Editor Matrix record overflow critical CVE exact CVE_2018_0798
    RTF contains hex-encoded MTEF Matrix record exploit signature (NOP-sled 0x60 + padding 0x61 + return address 0x0BFB). CVE-2018-0798 exploits a stack buffer overflow in EQNEDT32.EXE's Matrix record parser and affected Equation Editor broadly, including builds patched for CVE-2017-11882. Widely used by APT groups (Conimes, KeyBoy, Emissary Panda, Rancor).
  • 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.
  • ClamAV: Rtf.Dropper.Agent-6965878-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Rtf.Dropper.Agent-6965878-0
  • \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.
  • Package object class high RTF_OBJCLASS_PACKAGE
    OLE Package object — can wrap arbitrary files
  • OLE object data medium RTF_OBJDATA
    RTF contains 3 \objdata section(s) — embedded OLE objects
  • Embedded OLE object medium RTF_OBJEMB
    RTF contains \objemb — embedded OLE object

Extracted artifacts 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off000111c9.bin rtf-objdata-decoded RTF \objdata at offset 0x111C9 116976 bytes
SHA-256: 4966cc72d331f91e61d0a335083915c63181d4ab0c2da338fa7a58a0d27103c4
objdata_01_off0004a3df.bin rtf-objdata-decoded RTF \objdata at offset 0x4A3DF 11842 bytes
SHA-256: 82a0e9d2b46fe974ae1d3298ffd405eb8e6ea8fda7665fef57d4e0d76c604d9d
objdata_02_off0004a3f1.bin rtf-objdata-decoded RTF \objdata at offset 0x4A3F1 35 bytes
SHA-256: d0771b17e6418e479f528fc4aa124822669975a78f8dc3e35cdc4b0f7c212c4e

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