Load Of RstrtMgr.DLL By A Suspicious Process

Status: test
Severity: high
Log source: product windows, category image_load
Author: Luc Génaux
Source: github.com/SigmaHQ/sigma

Detects the load of RstrtMgr DLL (Restart Manager) by a suspicious process. This library has been used during ransomware campaigns to kill processes that would prevent file encryption by locking them (e.g. Conti ransomware, Cactus ransomware). It has also recently been seen used by the BiBi wiper for Windows. It could also be used for anti-analysis purposes by shut downing specific processes.

MITRE ATT&CK coverage

Tactic	Techniques
Defense Impairment	`T1685` Disable or Modify Tools
Impact	`T1486` Data Encrypted for Impact

Event coverage

Provider	Event	Title
Sysmon	Event ID 7	Image loaded

Rule body yaml

title: Load Of RstrtMgr.DLL By A Suspicious Process
id: b48492dc-c5ef-4572-8dff-32bc241c15c8
related:
    - id: 3669afd2-9891-4534-a626-e5cf03810a61
      type: derived
status: test
description: |
    Detects the load of RstrtMgr DLL (Restart Manager) by a suspicious process.
    This library has been used during ransomware campaigns to kill processes that would prevent file encryption by locking them (e.g. Conti ransomware, Cactus ransomware). It has also recently been seen used by the BiBi wiper for Windows.
    It could also be used for anti-analysis purposes by shut downing specific processes.
references:
    - https://www.crowdstrike.com/blog/windows-restart-manager-part-1/
    - https://www.crowdstrike.com/blog/windows-restart-manager-part-2/
    - https://web.archive.org/web/20231221193106/https://www.swascan.com/cactus-ransomware-malware-analysis/
    - https://taiwan.postsen.com/business/88601/Hamas-hackers-use-data-destruction-software-BiBi-which-consumes-a-lot-of-processor-resources-to-wipe-Windows-computer-data--iThome.html
author: Luc Génaux
date: 2023-11-28
tags:
    - attack.impact
    - attack.defense-impairment
    - attack.t1486
    - attack.t1685
logsource:
    category: image_load
    product: windows
detection:
    selection_img:
        - ImageLoaded|endswith: '\RstrtMgr.dll'
        - OriginalFileName: 'RstrtMgr.dll'
    selection_folders_1:
        Image|contains:
            # Note: increase coverage by adding more suspicious paths
            - ':\Perflogs\'
            - ':\Users\Public\'
            - '\Temporary Internet'
    selection_folders_2:
        - Image|contains|all:
              - ':\Users\'
              - '\Favorites\'
        - Image|contains|all:
              - ':\Users\'
              - '\Favourites\'
        - Image|contains|all:
              - ':\Users\'
              - '\Contacts\'
    condition: selection_img and 1 of selection_folders_*
falsepositives:
    - Processes related to software installation
level: high

Stages and Predicates

Stage 0: `condition`

selection_img and 1 of selection_folders_*

Stage 1: `selection_img`

selection_img:
    - ImageLoaded|endswith: '\RstrtMgr.dll'
    - OriginalFileName: 'RstrtMgr.dll'

Stage 2: `selection_folders_1`

selection_folders_1:
    Image|contains:
        - ':\Perflogs\'
        - ':\Users\Public\'
        - '\Temporary Internet'

Stage 3: `selection_folders_2`

selection_folders_2:
    - Image|contains|all:
          - ':\Users\'
          - '\Favorites\'
    - Image|contains|all:
          - ':\Users\'
          - '\Favourites\'
    - Image|contains|all:
          - ':\Users\'
          - '\Contacts\'

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.

Field	Kind	Values
`Image`	match	`:\Perflogs\` corpus 10 (sigma 10) `:\Users\` corpus 3 (sigma 3) `:\Users\Public\` corpus 15 (sigma 15) `\Contacts\` corpus 5 (sigma 5) `\Favorites\` corpus 6 (sigma 6) `\Favourites\` corpus 5 (sigma 5) `\Temporary Internet` corpus 2 (sigma 2)
`ImageLoaded`	ends_with	`\RstrtMgr.dll` corpus 2 (sigma 2)
`OriginalFileName`	eq	`RstrtMgr.dll` corpus 2 (sigma 2)

`j` / `k`	Scroll down / up
`d` / `u`	Half-page down / up
`gg` / `G`	Top / bottom
`h` / `l`	History back / forward
`f`	Follow link (`Shift` = new tab)
`/`	Focus search
`?`	Toggle this help
`↑` / `↓`	Navigate search results
`Enter`	Open highlighted result
`Esc`	Close results / dialog

`type:`	`events` / `rules` / `providers`
`vendor:`	`sigma` / `elastic` / `splunk` / `kusto` / `chronicle` (vendor name alone also works: `sigma:`, `kql:`, `secops:`…)
`tactic:`	TA-id, slug, or name: `credential_access`, `TA0006`
`technique:`	technique or sub-technique ID: `T1003`, `T1003.001` (alias `tech:`)
`severity:`	`critical` / `high` / `medium` / `low` / `informational` (alias `sev:`)
`risk_score`	Numeric comparison on the Elastic risk score (0 to 100): `risk_score>50`, `risk_score<=20`, `risk_score=99` (alias `risk`; Elastic rules only)
`stages:`	Rules with exactly N pipeline stages
`correlation:`	`single_event` / `sequence` / `alternatives` / `alternatives_cross_log` / `all_required` / `correlated`
`with:`	Co-occurrence event-id; stacks (`with:4624 with:4769`) to require all, while a comma list in one occurrence (`with:4624,4769`) is an either-or group. Implies multi-event
`like:`	Structural neighbors of a rule slug (equivalents + subsumption stricter / broader): `like:comsvcs_lsass_memory_dump-splunk-sysmon`
`groupby:`	Entity-grouping substring match against `group_by_keys`: `groupby:user`, `groupby:host`
`uses:`	Rules whose predicate tree touches the field (any kind, any value): `uses:CommandLine`
`excludes:`	Rules with top-level `not()` clauses on the field (FP whitelists): `excludes:ParentImage`
`field:` / `value:`	Predicate search; narrows rule cards to those with a matching leaf and drives the indicator tier. Unquoted = substring, wildcards allowed (`value:mimikatz`)
`indicator:`	Shorthand for `field:F value:V`: `indicator:Image=*\powershell.exe`
`kind:`	Filter by predicate kind. Narrows rule cards to those carrying a matching predicate leaf (`vendor:elastic kind:cidr_match`) and drives the indicator tier: `contains` / `starts_with` / `ends_with` / `regex` / `cidr` / `eq` / `in` … (operator aliases `op:`/`match:`)
`has:` / `no:`	`sample`, `field`, `notes`, `refs`, `trace`, `thirdparty`, `rule`, `pattern`, `timewindow`, `threshold`, `newterms`, `sigma`/`elastic`/`splunk`/`kusto`/`chronicle`
`-op:val`	Exclude matches; works on most operators but not `type:`/`like:`/`has:`/`no:` (use `no:<flag>` to exclude a rule flag): `tactic:execution -vendor:splunk`. Standalone `-kind:`/`-field:`/`-value:` drop every rule carrying a matching predicate leaf (`type:rules -kind:is_null`)
`field:"…"` / `value:"…"`	Quoted value = anchored exact match (also allows spaces): `value:"net user"`
`a,b`	Comma = OR inside one operator (`vendor:sigma,elastic`, `severity:high,critical`); repeating a facet merges the same way. `field:`/`value:` never split (literal commas)
`vendors:` / `stage:`	Singular and plural spellings fold to the canonical operator and value: `tactics:` = `tactic:`, `type:event` = `type:events`, `correlation:sequences` = `correlation:sequence`, `has:thresholds` = `has:threshold`
`"quoted phrase"`	Exact-match a multi-word phrase (free text)

Load Of RstrtMgr.DLL By A Suspicious Process

MITRE ATT&CK coverage

Event coverage

Rule body yaml

Stages and Predicates

Stage 0: `condition`

Stage 1: `selection_img`

Stage 2: `selection_folders_1`

Stage 3: `selection_folders_2`

Indicators

Keyboard shortcuts

Search operators

Load Of RstrtMgr.DLL By A Suspicious Process

MITRE ATT&CK coverage

Event coverage

Rule body yaml

Stages and Predicates

Stage 0: condition

Stage 1: selection_img

Stage 2: selection_folders_1

Stage 3: selection_folders_2

Indicators

Stage 0: `condition`

Stage 1: `selection_img`

Stage 2: `selection_folders_1`

Stage 3: `selection_folders_2`