ClamAV e MalDet - estão em quarentena ou estão infectados?

3

Aprendendo sobre o endurecimento do meu VPS, eu instalei o ClamAV e o MalDet, usando ambos por alguns meses. Hoje à noite, eu decidi que, em vez de apenas checar a casa, eu verificaria o VPS inteiro além de "/ sys".

Este foi o resultado:

/usr/local/maldetect.bk11949/sigs/rfxn.ndb: YARA.Safe0ver_Shell__Safe_Mod_Bypass_By_Evilc0der_php.UNOFFICIAL FOUND
/usr/local/maldetect.bk11949/sigs/hex.dat: YARA.Safe0ver_Shell__Safe_Mod_Bypass_By_Evilc0der_php.UNOFFICIAL FOUND
/usr/local/maldetect.bk11949/sigs/rfxn.hdb: YARA.Safe0ver_Shell__Safe_Mod_Bypass_By_Evilc0der_php.UNOFFICIAL FOUND
/usr/local/maldetect.bk11949/sigs/md5.dat: YARA.Safe0ver_Shell__Safe_Mod_Bypass_By_Evilc0der_php.UNOFFICIAL FOUND
/usr/local/maldetect.bk11949/sigs/rfxn.yara: {HEX}gzbase64.inject.unclassed.15.UNOFFICIAL FOUND
/usr/local/maldetect.bk11949/sigs/md5v2.dat: YARA.Safe0ver_Shell__Safe_Mod_Bypass_By_Evilc0der_php.UNOFFICIAL FOUND
/usr/local/maldetect.bk11949/tmp/.lmdup.666.11852/maldetect-current.tar.gz: YARA.Safe0ver_Shell__Safe_Mod_Bypass_By_Evilc0der_php.UNOFFICIAL FOUND
/usr/local/maldetect.bk11949/tmp/.lmdup.666.11852/maldetect-1.6/files/sigs/rfxn.ndb: YARA.Safe0ver_Shell__Safe_Mod_Bypass_By_Evilc0der_php.UNOFFICIAL FOUND
/usr/local/maldetect.bk11949/tmp/.lmdup.666.11852/maldetect-1.6/files/sigs/hex.dat: YARA.Safe0ver_Shell__Safe_Mod_Bypass_By_Evilc0der_php.UNOFFICIAL FOUND
/usr/local/maldetect.bk11949/tmp/.lmdup.666.11852/maldetect-1.6/files/sigs/rfxn.hdb: YARA.Safe0ver_Shell__Safe_Mod_Bypass_By_Evilc0der_php.UNOFFICIAL FOUND
/usr/local/maldetect.bk11949/tmp/.lmdup.666.11852/maldetect-1.6/files/sigs/md5.dat: YARA.Safe0ver_Shell__Safe_Mod_Bypass_By_Evilc0der_php.UNOFFICIAL FOUND
/usr/local/maldetect.bk11949/tmp/.lmdup.666.11852/maldetect-1.6/files/sigs/rfxn.yara: {HEX}gzbase64.inject.unclassed.15.UNOFFICIAL FOUND
/usr/local/maldetect.bk11949/tmp/.lmdup.666.11852/maldetect-1.6/files/sigs/md5v2.dat: YARA.Safe0ver_Shell__Safe_Mod_Bypass_By_Evilc0der_php.UNOFFICIAL FOUND
/usr/local/maldetect.bk11949/tmp/.lmdup.666.11852/maldetect-1.6/files/clean/gzbase64.inject.unclassed: {HEX}gzbase64.inject.unclassed.15.UNOFFICIAL FOUND
/usr/local/maldetect.bk11949/clean/gzbase64.inject.unclassed: {HEX}gzbase64.inject.unclassed.15.UNOFFICIAL FOUND
/usr/local/maldetect.bk11949/sigs.old/rfxn.ndb: YARA.Safe0ver_Shell__Safe_Mod_Bypass_By_Evilc0der_php.UNOFFICIAL FOUND
/usr/local/maldetect.bk11949/sigs.old/hex.dat: YARA.Safe0ver_Shell__Safe_Mod_Bypass_By_Evilc0der_php.UNOFFICIAL FOUND
/usr/local/maldetect.bk11949/sigs.old/rfxn.hdb: YARA.Safe0ver_Shell__Safe_Mod_Bypass_By_Evilc0der_php.UNOFFICIAL FOUND
/usr/local/maldetect.bk11949/sigs.old/md5.dat: YARA.Safe0ver_Shell__Safe_Mod_Bypass_By_Evilc0der_php.UNOFFICIAL FOUND
/usr/local/maldetect.bk11949/sigs.old/rfxn.yara: {HEX}gzbase64.inject.unclassed.15.UNOFFICIAL FOUND
/usr/local/maldetect.bk11949/sigs.old/md5v2.dat: YARA.Safe0ver_Shell__Safe_Mod_Bypass_By_Evilc0der_php.UNOFFICIAL FOUND
/usr/local/maldetect/sigs/rfxn.ndb: YARA.Safe0ver_Shell__Safe_Mod_Bypass_By_Evilc0der_php.UNOFFICIAL FOUND
/usr/local/maldetect/sigs/hex.dat: YARA.Safe0ver_Shell__Safe_Mod_Bypass_By_Evilc0der_php.UNOFFICIAL FOUND
/usr/local/maldetect/sigs/rfxn.hdb: YARA.Safe0ver_Shell__Safe_Mod_Bypass_By_Evilc0der_php.UNOFFICIAL FOUND
/usr/local/maldetect/sigs/md5.dat: YARA.Safe0ver_Shell__Safe_Mod_Bypass_By_Evilc0der_php.UNOFFICIAL FOUND
/usr/local/maldetect/sigs/rfxn.yara: {HEX}gzbase64.inject.unclassed.15.UNOFFICIAL FOUND
/usr/local/maldetect/sigs/md5v2.dat: YARA.Safe0ver_Shell__Safe_Mod_Bypass_By_Evilc0der_php.UNOFFICIAL FOUND
/usr/local/maldetect/clean/gzbase64.inject.unclassed: {HEX}gzbase64.inject.unclassed.15.UNOFFICIAL FOUND
/usr/local/src/maldetect-1.5/files/sigs/rfxn.ndb: YARA.Safe0ver_Shell__Safe_Mod_Bypass_By_Evilc0der_php.UNOFFICIAL FOUND
/usr/local/src/maldetect-1.5/files/sigs/hex.dat: YARA.Safe0ver_Shell__Safe_Mod_Bypass_By_Evilc0der_php.UNOFFICIAL FOUND
/usr/local/src/maldetect-1.5/files/sigs/rfxn.hdb: YARA.Safe0ver_Shell__Safe_Mod_Bypass_By_Evilc0der_php.UNOFFICIAL FOUND
/usr/local/src/maldetect-1.5/files/sigs/md5.dat: YARA.Safe0ver_Shell__Safe_Mod_Bypass_By_Evilc0der_php.UNOFFICIAL FOUND
/usr/local/src/maldetect-1.5/files/sigs/md5v2.dat: YARA.Safe0ver_Shell__Safe_Mod_Bypass_By_Evilc0der_php.UNOFFICIAL FOUND
/usr/local/src/maldetect-1.5/files/clean/gzbase64.inject.unclassed: {HEX}gzbase64.inject.unclassed.15.UNOFFICIAL FOUND
/usr/local/src/maldetect-current.tar.gz: YARA.Safe0ver_Shell__Safe_Mod_Bypass_By_Evilc0der_php.UNOFFICIAL FOUND
/usr/share/clamav/rfxn.ndb: YARA.Safe0ver_Shell__Safe_Mod_Bypass_By_Evilc0der_php.UNOFFICIAL FOUND
/usr/share/clamav/rfxn.hdb: YARA.Safe0ver_Shell__Safe_Mod_Bypass_By_Evilc0der_php.UNOFFICIAL FOUND
/usr/share/clamav/rfxn.yara: {HEX}gzbase64.inject.unclassed.15.UNOFFICIAL FOUND
/var/lib/clamav/rfxn.ndb: YARA.Safe0ver_Shell__Safe_Mod_Bypass_By_Evilc0der_php.UNOFFICIAL FOUND
/var/lib/clamav/rfxn.hdb: YARA.Safe0ver_Shell__Safe_Mod_Bypass_By_Evilc0der_php.UNOFFICIAL FOUND
/var/lib/clamav/rfxn.yara: {HEX}gzbase64.inject.unclassed.15.UNOFFICIAL FOUND

Known viruses: 6109455
Engine version: 0.99.2
Scanned directories: 8699
Scanned files: 62104
Infected files: 41
Data scanned: 2514.92 MB
Data read: 4509.22 MB (ratio 0.56:1)
Time: 606.692 sec (10 m 6 s)

Então ... agora estou com medo, já que não vejo isso como nada além de más notícias.

Por favor, avise.

    
por Steven Ventimiglia 23.03.2017 / 04:19

1 resposta

5

YARA é uma ferramenta usada por várias proteções contra malware usadas para criar a descrição de famílias de malware com base em padrões textuais binários. O malware detectado, " Safe0ver Shell -Safe Mod Bypass por Evilc0der.php ", parece um webshell PHP, uma ferramenta de exploração que provavelmente é usada para obter acesso shell em servidores vulneráveis executando PHP.

No entanto, os locais onde o malware foi encontrado estão em diretórios nos quais o CalmAV ou o MalDet armazena seus arquivos de assinatura . Além disso, para estar ativo, o malware detectado deve estar no formato original (tipo MIME application/x-httpd-php ), o que não é. Os arquivos de assinatura devem conter informações suficientes sobre o malware para detectá-lo, o que pode causar falsos positivos quando os arquivos de assinatura são verificados com uma ferramenta de detecção de malware.

A saída parece ser do ClamAV. O ClamAV é originalmente projetado para escanear e-mails (e sites) em vez de sistemas de arquivos inteiros. Isso aumenta ainda mais a taxa de falsos positivos.

Você pode excluir esses diretórios. Para isso

  • clamscan tem opção

    --exclude=REGEX, --exclude-dir=REGEX
        Don't scan file/directory names matching regular expression.
        These options can be used multiple times
    
  • clamdscan usa clamd.conf - Arquivo de configuração para o Clam AntiVirus Daemon. O local do arquivo de configuração pode ser definido pela opção --config-file=FILE e o arquivo de configuração aceita ExcludePath REGEX diretivas.

  • O Linux Malware Detect tem um arquivo para listar os caminhos a serem ignorados:

    .: 8 [ IGNORE OPTIONS ]
    
    There are four ignore files available and they break down as follows:
    
    /usr/local/maldetect/ignore_paths
    A line spaced file for paths that are to be execluded from search results
     Sample ignore entry:
     /home/user/public_html/cgi-bin
    
por 23.03.2017 / 12:36