98 lines
3.7 KiB
Markdown
98 lines
3.7 KiB
Markdown
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# Post-Exploitation
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## Pilfering
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* retrieve useful information from machine
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* passwords (`/etc/shadow`, `hashdump` SAM database)
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* cryptographic keys (SSH, PGP, GPG)
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* `/etc/passwd` format: fields separated by colons
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* `jef:$y$salty$youwish:20022:0:99999:7:::`
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1. `jef`: username
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2. `$1$salty$youwish`: hash id, salt and password hash
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3. `20022`: day password was last changed (unix timestamp but in days)
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4. `0`: minimum age of password before it can be changed again
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5. `99999`: max age of password, after how many days password must be
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changed
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6. `7`: how many days before expiring the user should be warned
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7. number of days after password expired that user should be locked out
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(usually empty)
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8. expiration date of account
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* moving files
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* push file directly if firewall allows it
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* otherwise send command to target to pull target from client
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* use whatever protocol works best (FTP, SMB...)
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* meterpreter supports sending files
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* Windows
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* user credentials cached in Microsoft Credential Manager
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* extract using credential cache dumping tools
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* requires admin
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* service account passwords stored encrypted in LSA secrets section of
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registry
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* Mimikatz `lsadump` can dump these
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* wireless client profiles can be extracted if admin
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* other
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* source code of services for vulnerability analysis
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* scripts for hardcoded passwords
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* files left behind by users that shouldn't be
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* browser passwords
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* machines with which machine has recently communicated (find pivot
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targets)
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* DNS servers
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* web servers
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* mail
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* ...
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## Password attacks
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* guessing
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* generates lots of traffic
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* can lock out accounts
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* slower than cracking
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* **spray attack**: try single password on list of users
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* cracking
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* steal hashed password and compare hashes
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* runs on attacker's machine -> stealthier
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* important for assessing security posture of network
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1. access control evaluation
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* assess password strength
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* password policies
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2. credential-based attacks
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* **brute force**: try many combination to expose weak or default
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passwords
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* **dictionary**: use list of common password
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* **credential stuffing**: use credentials from previous breaches
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3. privilege escalation
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4. social engineering: trick users into revealing passwords
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* MFA
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* prevent leak of password from becoming a breach
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* bypassing
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* phishing or man-in-the-middle
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* expose implementation flaws
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* insecure methods, e.g. SMS or email
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* session hijacking, e.g. intercepting cookies
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* social engineering, e.g. pose as tech support
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* SIM swapping: get victim's phone number reassigned to new SIM card
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* use backup codes or account recovery
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* push notification bombing
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* using dictionaries
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* large word list for password cracking
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* small tailored list for password guessing
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* cracking not always needed
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* sniff cleartext protocols
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* keystroke logging
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* pass-the-hash techniques use hash directly
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* clean up after pentest (don't leave cracked passwords lying around)
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* lockouts
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* password guessing can lock accounts
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* Windows: original admin account can't be locked out
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* admin has SID suffix of 500
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* if multiple admin accounts, only 1 is safe
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* Linux: lockouts not always configured
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* if so, done using PAM
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* root account not locked out by default
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* prevention
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* just don't guess passwords
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* ask target personnel for info on policy
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* create test account for pentest
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* attempt 1 password per observation window
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