ASLR Disabled Via Sysctl or Direct Syscall - Linux

Status: experimental
Severity: high
Log source: product linux, service auditd
Author: Milad Cheraghi
Source: github.com/SigmaHQ/sigma

Detects actions that disable Address Space Layout Randomization (ASLR) in Linux, including: - Use of the personality syscall with the ADDR_NO_RANDOMIZE flag (0x0040000) - Modification of the /proc/sys/kernel/randomize_va_space file - Execution of the sysctl command to set kernel.randomize_va_space=0 Disabling ASLR is often used by attackers during exploit development or to bypass memory protection mechanisms. A successful use of these methods can reduce the effectiveness of ASLR and make memory corruption attacks more reliable.

Known false positives

Debugging or legitimate software testing

MITRE ATT&CK coverage

Tactic	Techniques
Privilege Escalation	`T1055.009` Process Injection: Proc Memory
Stealth	`T1055.009` Process Injection: Proc Memory
Defense Impairment	`T1685` Disable or Modify Tools

Telemetry coverage

Platform	Record / event type
Linux	auditd SYSCALL record: System call event information
Linux	auditd EXECVE record: Arguments supplied to the execve system call

Rule body

title: ASLR Disabled Via Sysctl or Direct Syscall - Linux
id: e497a24e-9345-4a62-9803-b06d7d7cb132
status: experimental
description: |
    Detects actions that disable Address Space Layout Randomization (ASLR) in Linux, including:
      - Use of the `personality` syscall with the ADDR_NO_RANDOMIZE flag (0x0040000)
      - Modification of the /proc/sys/kernel/randomize_va_space file
      - Execution of the `sysctl` command to set `kernel.randomize_va_space=0`
    Disabling ASLR is often used by attackers during exploit development or to bypass memory protection mechanisms.
    A successful use of these methods can reduce the effectiveness of ASLR and make memory corruption attacks more reliable.
references:
    - https://github.com/CheraghiMilad/bypass-Neo23x0-auditd-config/blob/f1c478a37911a5447d5ffcd580f22b167bf3df14/personality-syscall/README.md
    - https://man7.org/linux/man-pages/man2/personality.2.html
    - https://manual.cs50.io/2/personality
    - https://linux-audit.com/linux-aslr-and-kernelrandomize_va_space-setting/
author: Milad Cheraghi
date: 2025-05-26
modified: 2025-12-05
tags:
    - attack.privilege-escalation
    - attack.stealth
    - attack.defense-impairment
    - attack.t1685
    - attack.t1055.009
logsource:
    product: linux
    service: auditd
detection:
    selection_syscall:
        type: 'SYSCALL'
        SYSCALL: 'personality'
        a0: 40000
    selection_sysctl:
        type: 'EXECVE'
        a0: 'sysctl'
        a1: '-w'
        a2: 'kernel.randomize_va_space=0' # 0 = disable
    condition: 1 of selection_*
falsepositives:
    - Debugging or legitimate software testing
level: high

Stages and Predicates

Stage 0: `condition`

1 of selection_*

Stage 1: `selection_syscall`

selection_syscall:
    type: 'SYSCALL'
    SYSCALL: 'personality'
    a0: 40000

Stage 2: `selection_sysctl`

selection_sysctl:
    type: 'EXECVE'
    a0: 'sysctl'
    a1: '-w'
    a2: 'kernel.randomize_va_space=0'

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`SYSCALL`	eq	`personality`	`field:"SYSCALL" kind:eq value:"personality"`
`a0`	eq	`40000` `sysctl`	`field:"a0" kind:eq`
`a1`	eq	`-w`	`field:"a1" kind:eq value:"-w"`
`a2`	eq	`kernel.randomize_va_space=0`	`field:"a2" kind:eq value:"kernel.randomize_va_space=0"`
`type`	eq	`EXECVE` `SYSCALL`	`field:"type" kind:eq`