Detection rules › Splunk

Download Files Using Telegram

Author
Teoderick Contreras, Splunk
Source
upstream

The following analytic detects suspicious file downloads by the Telegram application on a Windows system. It leverages Sysmon EventCode 15 to identify instances where Telegram.exe creates files with a Zone.Identifier, indicating a download. This activity is significant as it may indicate an adversary using Telegram to download malicious tools, such as network scanners, for further exploitation. If confirmed malicious, this behavior could lead to network mapping, lateral movement, and potential compromise of additional systems within the network.

MITRE ATT&CK coverage

TacticTechniques
Command & ControlT1105 Ingress Tool Transfer

Event coverage

ProviderEvent IDTitle
Sysmon15FileCreateStreamHash

Stages and Predicates

Stage 1: search

search EventCode=15 TargetFilename="*:Zone.Identifier" process_name="telegram.exe"

Stage 2: stats

stats BY dest, dvc, file_hash, file_name, file_path, process_exec, process_guid, process_id, process_name, process_path, signature, signature_id, user_id, vendor_product, Contents, Image

Stage 3: search

search

Stage 4: search

search

Stage 5: search

search `macro`

Indicators

Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.

FieldKindValues
EventCodeeq
  • 15 corpus 3 (splunk 3)
TargetFilenameeq
  • "*:Zone.Identifier" corpus 2 (splunk 2)
process_nameeq
  • "telegram.exe"