Detection: Download Files Using Telegram

Updated Date: 2024-05-23 ID: 58194e28-ae5e-11eb-8912-acde48001122 Author: Teoderick Contreras, Splunk Type: TTP Product: Splunk Enterprise Security

Description

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.

Search

1`sysmon` EventCode= 15 process_name = "telegram.exe" TargetFilename = "*:Zone.Identifier" 
2|stats count min(_time) as firstTime max(_time) as lastTime by dest EventCode process_name process_id TargetFilename Hash 
3| `security_content_ctime(firstTime)` 
4| `security_content_ctime(lastTime)` 
5| `download_files_using_telegram_filter`

Data Source

Name	Platform	Sourcetype	Source	Supported App
Sysmon EventID 15	Windows	`'xmlwineventlog'`	`'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational'`	N/A

Macros Used

Name	Value
security_content_ctime	`convert timeformat="%Y-%m-%dT%H:%M:%S" ctime($field$)`
download_files_using_telegram_filter	`search *`

download_files_using_telegram_filter is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Annotations

- MITRE ATT&CK

+ Kill Chain Phases

+ NIST

+ CIS

- Threat Actors

ID	Technique	Tactic
T1105	Ingress Tool Transfer	Command And Control

KillChainPhase.COMMAND_AND_CONTROL

NistCategory.DE_CM

Cis18Value.CIS_10

APT-C-36

APT18

APT28

APT29

APT3

APT32

APT33

APT37

APT38

APT39

APT41

Ajax Security Team

Andariel

Aquatic Panda

BITTER

BRONZE BUTLER

BackdoorDiplomacy

Chimera

Cinnamon Tempest

Cobalt Group

Confucius

Darkhotel

Dragonfly

Elderwood

Ember Bear

Evilnum

FIN13

FIN7

FIN8

Fox Kitten

GALLIUM

Gamaredon Group

Gorgon Group

HAFNIUM

HEXANE

IndigoZebra

Indrik Spider

Ke3chang

Kimsuky

Lazarus Group

LazyScripter

Leviathan

LuminousMoth

Magic Hound

Metador

Molerats

Moses Staff

MuddyWater

Mustang Panda

Mustard Tempest

Nomadic Octopus

OilRig

PLATINUM

Patchwork

Rancor

Rocke

Sandworm Team

SideCopy

Sidewinder

Silence

TA2541

TA505

TA551

TeamTNT

Threat Group-3390

Tonto Team

Tropic Trooper

Turla

Volatile Cedar

WIRTE

Whitefly

Windshift

Winnti Group

Wizard Spider

ZIRCONIUM

menuPass

Default Configuration

This detection is configured by default in Splunk Enterprise Security to run with the following settings:

Setting	Value
Disabled	true
Cron Schedule	`0 * * * *`
Earliest Time	`-70m@m`
Latest Time	`-10m@m`
Schedule Window	`auto`
Creates Notable	Yes
Rule Title	`%name%`
Rule Description	`%description%`
Notable Event Fields	user, dest
Creates Risk Event	True

This configuration file applies to all detections of type TTP. These detections will use Risk Based Alerting and generate Notable Events.

Implementation

To successfully implement this search, you need to be ingesting logs with the process name and TargetFilename from your endpoints or Events that monitor filestream events which is happened when process download something. (EventCode 15) If you are using Sysmon, you must have at least version 6.0.4 of the Sysmon TA.

Known False Positives

normal download of file in telegram app. (if it was a common app in network)

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message	Risk Score	Impact	Confidence
Suspicious files were downloaded with the Telegram application on $dest$	49	70	70

The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.

References

https://thedfirreport.com/2020/04/20/sqlserver-or-the-miner-in-the-basement/

Detection Testing

Test Type	Status	Dataset	Source	Sourcetype
Validation	✅ Passing	N/A	N/A	N/A
Unit	✅ Passing	Dataset	`XmlWinEventLog:Microsoft-Windows-Sysmon/Operational`	`xmlwineventlog`
Integration	✅ Passing	Dataset	`XmlWinEventLog:Microsoft-Windows-Sysmon/Operational`	`xmlwineventlog`

Replay any dataset to Splunk Enterprise by using our replay.py tool or the UI. Alternatively you can replay a dataset into a Splunk Attack Range

Source: GitHub | Version: 2