Inefficient complexity in the Sieve filter evaluation of Progressive Robot hMailServer 6.2.24 through 6.3.5 allows an authenticated account holder to make the mail services unavailable with their own filter. A ':matches' pattern was matched by a backtracking descent whose time grew with the matched value's length raised to the number of wildcards, so a pattern such as '*a*a*a*b' over 800 characters took 44 seconds; and 'deleteheader' erased the fields it removed one at a time, so removing many fields of one name over a message's header cost O(N^2) (80,000 fields took 18.8 seconds). Sieve filters run on the small, shared delivery thread pool, so an account holder whose active script does this, fed a few messages they can send themselves, empties the pool and stops delivery for the whole server. The script is the account holder's own and cannot be set for another user.
| Métrique | Valeur | Interprétation |
|---|---|---|
|
AV (Vecteur d'Attaque)
Attack Vector
|
Network (N)
|
Exploit possible à distance via réseau (HTTP, API, etc.) |
|
AC (Complexité d'Attaque)
Attack Complexity
|
Low (L)
|
Peu de conditions requises pour exploiter |
|
PR (Privilèges Requis)
Privileges Required
|
Low (L)
|
Authentifié avec compte utilisateur basique |
|
UI (Interaction Utilisateur)
User Interaction
|
None (N)
|
Aucune interaction utilisateur nécessaire |
|
S (Périmètre)
Scope
|
Unchanged (U)
|
Impact reste dans le périmètre du composant compromis |
|
C (Impact Confidentialité)
Confidentiality Impact
|
None (N)
|
Aucune divulgation d'informations |
|
I (Impact Intégrité)
Integrity Impact
|
None (N)
|
Aucune modification de données possible |
|
A (Impact Disponibilité)
Availability Impact
|
High (H)
|
Interruption totale du service possible |
Inefficient Regular Expression Complexity in hMailServer