ICE 0xF1

ICEBP is an undocumented instruction that serves as a single byte interrupt 1, generating a single step exception. It can be used to detect if the program is traced.

Technique Identifier

U0130

Technique Tags

0xf1 icebp

Featured Windows API's

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IsDebuggerPresent

Evasion Categories

Anti-Debugging

Code Snippets

BOOL IsDebuggerPresent_IceBp()
{
    __try
    { 
        __asm __emit 0xF1 
    }
    __except(1) 
    { 
        return FALSE; 
    }
    return TRUE;
}

About Author Open Snippet

Author: External / Target Platform: Windows

Detection Rules

rule Detect_Interrupt: AntiDebug {
    meta: 
        description = "Detect Interrupt instruction"
        author = "Unprotect"
        comment = "Experimental rule / the rule can be slow to use"
    strings:
        $int3 = { CC }
        $intCD = { CD }
        $int03 = { 03 }
        $int2D = { 2D }
        $ICE = { F1 }
    condition:   
       uint16(0) == 0x5A4D and filesize < 1000KB and any of them
}

rule:
  meta:
    name: execute anti-debugging instructions
    namespace: anti-analysis/anti-debugging/debugger-detection
    authors:
      - moritz.raabe@mandiant.com
    scope: function
    mbc:
      - Anti-Behavioral Analysis::Debugger Detection::Anti-debugging Instructions [B0001.034]
    examples:
      - Practical Malware Analysis Lab 16-03.exe_:0x401300
  features:
    - or:
      - count(mnemonic(rdtsc)): 2 or more
      - mnemonic: icebp

Contributor

Thomas Roccia (fr0gger)

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Created

June 22, 2022

Last Revised

March 24, 2026