Detection rules › Sigma
Uncommon Link.EXE Parent Process
Detects an uncommon parent process of "LINK.EXE". Link.EXE in Microsoft incremental linker. Its a utility usually bundled with Visual Studio installation. Multiple utilities often found in the same folder (editbin.exe, dumpbin.exe, lib.exe, etc) have a hardcode call to the "LINK.EXE" binary without checking its validity. This would allow an attacker to sideload any binary with the name "link.exe" if one of the aforementioned tools get executed from a different location. By filtering the known locations of such utilities we can spot uncommon parent process of LINK.EXE that might be suspicious or malicious.
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Defense Evasion | T1218 System Binary Proxy Execution |
Event coverage
| Provider | Event ID | Title |
|---|---|---|
| Sysmon | 1 | Process creation |
| Security-Auditing | 4688 | A new process has been created. |
Stages and Predicates
Stage 1: selection
CommandLine|contains: 'LINK /'
Image|endswith: '\link.exe'
Stage 2: not 1 of filter_main_visual_studio
or:
ParentImage|contains: '\VC\Tools\'
ParentImage|contains: '\VC\bin\'
or:
ParentImage|startswith: 'C:\Program Files (x86)\Microsoft Visual Studio\'
ParentImage|startswith: 'C:\Program Files\Microsoft Visual Studio\'
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 |
|---|---|---|
CommandLine | match |
|
Image | ends_with |
|
ParentImage | match |
|
ParentImage | starts_with |
|