Small Sieve can obtain the IP address of a victim host.4
tool
Small Sieve S1035
- Type
- malware
- Platform
- Windows
- Created
- 16 August 2022
- Last modified
- 16 April 2025
Small Sieve is a Telegram Bot API-based Python backdoor that has been distributed using a Nullsoft Scriptable Install System (NSIS) Installer; it has been used by MuddyWater since at least January 2022.[1][2]
Security researchers have also noted Small Sieve's use by UNC3313, which may be associated with MuddyWater.[3]
13
Techniques57th pct
6
Tactics53rd pct
1
Threat groupunranked
0
CampaignsNone recorded
Enterprise ATT&CK only. Any Mobile or ICS rows on the same ATT&CK page are not carried.
MITRE reference S1035
Small Sieve has the ability to use a custom hex byte swapping encoding scheme combined with an obfuscated Base64 function to protect program strings and Telegram credentials.5
Small Sieve can obtain the id of a logged in user.6
Small Sieve can use variations of Microsoft and Outlook spellings, such as "Microsift", in its file names to avoid detection.7
Small Sieve can use cmd.exe to execute commands on a victim's system.8
Small Sieve can use Python scripts to execute commands.9
Standing S1035
Reach is how much of ATT&CK this tool touches. Coverage is how well defended each thing it does is, as a median per technique rather than a total — a total would just restate the reach. Each figure is ranked against all 825 ATT&CK software entries only where that population actually spreads. Where most of the population shares one value, a percentile would rank the tie instead of the entity, so the raw value is shown and no rank is claimed.
Reach
Techniques1357th pct
57th percentile · 57% of 825 ATT&CK software entries have this many Enterprise techniques or fewer.
Tactics653rd pct
53rd percentile · 53% of 825 ATT&CK software entries have this many tactics spanned or fewer.
Threat group161% tie · 22 values
61% of the population shares a single value across only 22 distinct values, so a percentile here would rank the tie, not the entity.
Campaigns085% tie · 8 values
85% of the population shares a single value across only 8 distinct values, so a percentile here would rank the tie, not the entity.
Coverage
Rules / technique27med68th pct
68th percentile · 68% of 825 ATT&CK software entries have this many detection rules per technique or fewer.
Tests / technique4med
Detection coverage S1035
508 distinct rules cover the 13 techniques recorded for this tool. The 534 technique-to-rule mappings resolve to 508 distinct rules, because one rule can cover several techniques. 388 Sigma · 120 Splunk.
12 covered by at least one rule1 with no coverage508 distinct rules in total
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