CUPP Leet Mode Character Combinations: The Complete 1337 Substitution Guide

CUPP’s leet mode supports eight specific character substitutions—a to 4, e to 3, i to 1, o to 0, s to 5, t to 7, g to 9, and z to 2—which are defined in the cupp.cfg configuration file and applied during wordlist generation.

The Common User Passwords Profiler (CUPP), hosted at Mebus/cupp, is a wordlist generation tool that mimics how users modify passwords to meet complexity requirements. Its leet mode (also known as 1337 speak) transforms candidate passwords by replacing alphabetic characters with visually similar numeric equivalents, significantly expanding the search space for password audits.

The 8 Character Mappings in CUPP Leet Mode

CUPP’s leet mode operates on exactly eight character combinations. These mappings are stored in the [leet] section of cupp.cfg (lines 19-26) and loaded into memory at runtime:

• a → 4
• e → 3
• i → 1
• o → 0
• s → 5
• t → 7
• g → 9
• z → 2

When active, the program iterates over this dictionary and replaces every occurrence of each letter with its corresponding digit.

How CUPP Implements Leet Mode

The leet substitution logic resides in cupp.py and executes through two distinct phases: configuration initialization and string transformation.

Configuration Loading

During startup, CUPP parses cupp.cfg and stores the leet mappings in the global CONFIG["LEET"] dictionary (lines 76-84). This structure enables constant-time lookups when processing candidate passwords.

The make_leet Function

The actual transformation occurs in the make_leet function (lines 95-99). This helper iterates over the configuration dictionary and applies substitutions sequentially:

def make_leet(x):
    for letter, number in CONFIG["LEET"].items():
        x = x.replace(letter, number)
    return x

Enabling Leet Mode in CUPP

You can activate leet mode through two primary workflows:

1. Interactive Profile Mode (-i): When generating a profile-based wordlist, CUPP prompts you to enable leet mode. Answering y triggers the transformation on all generated candidates.
2. Wordlist Improvement (-w): When enhancing existing wordlists, leet mode automatically applies the eight substitutions to each input word.

Practical Code Examples

When constructing a profile with leet mode enabled:

profile = {
    "name": "alice",
    "surname": "smith",
    "leetmode": "y"  # Activates 1337 substitution

}

# Generated variants include "4l1c3" and "sm17h"

Using the make_leet function directly in custom scripts:

from cupp import CONFIG, make_leet, read_config

# Initialize configuration including leet mappings

read_config("cupp.cfg")

# Transform strings using CUPP's leet logic

print(make_leet("password"))  # Output: p4ssw0rd

print(make_leet("test"))      # Output: 7357

Customizing Leet Character Combinations

The eight default mappings are fully extensible. You can customize CUPP’s leet mode by editing the [leet] section in cupp.cfg and adding new key-value pairs. For example, appending b = 8 or l = 1 extends the transformation logic without modifying the Python source code.

Summary

• CUPP’s leet mode supports eight character combinations: a→4, e→3, i→1, o→0, s→5, t→7, g→9, and z→2.
• Mappings are defined in cupp.cfg (lines 19-26) and loaded into CONFIG["LEET"] at runtime (lines 76-84).
• The make_leet function in cupp.py (lines 95-99) performs substitutions by iterating over the configuration dictionary.
• Enable leet mode via the -i interactive prompt or -w wordlist improvement options.
• You can extend supported combinations by adding entries to the [leet] section in cupp.cfg.

Frequently Asked Questions

What characters does CUPP replace in leet mode?

CUPP replaces eight alphabetic characters with digits: a becomes 4, e becomes 3, i becomes 1, o becomes 0, s becomes 5, t becomes 7, g becomes 9, and z becomes 2. These mappings are stored in the [leet] section of cupp.cfg and loaded into CONFIG["LEET"] during initialization.

How do I enable leet mode when generating wordlists?

You can enable leet mode by using the -i flag for interactive profile creation and responding y when prompted, or by using the -w flag when improving existing wordlists. Both methods trigger the make_leet function to process candidate passwords according to the mappings defined in cupp.cfg.

Can I add custom leet character combinations to CUPP?

Yes. Edit the cupp.cfg file and append new key-value pairs to the [leet] section following the existing format. CUPP automatically loads these custom mappings into CONFIG["LEET"] and applies them through the make_leet function without requiring changes to cupp.py.

Where is the leet mode logic implemented in the CUPP source code?

The leet mode logic is implemented in cupp.py. The configuration parser loads mappings into CONFIG["LEET"] at lines 76-84, while the substitution algorithm resides in the make_leet function at lines 95-99. The actual character definitions are stored in cupp.cfg at lines 19-26.

{
  "mcpServers": {
    "instagit": {
      "command": "npx",
      "args": ["-y", "instagit@latest"]
    }
  }
}