Various SSH implementations are vulnerable to a buffer overflow that allows a remote attacker to run arbitrary code. The SSH implementations include code for detection of a packet injection attack that would permit command execution. The code to detect the attack contains a vulnerability. A malicious user can overflow a 16-bit unsigned integer variable allowing memory address modification
Circuit level proxy (gateway?) is one that creates a circuit between the client and the server without interpreting the application protocol. Application level proxy is one that knows about the particular application it is providing proxy services for; it interprets the commands in the application protocol.
Pit against : 싸움시키다 , 경쟁시키다 .
From Zwicky, Building Internet Firewalls , second edition page 456
각 데이터 패킷은 데이터의 시작 옵셋과 끝 옵셋을 보유 . 이들이 겹칠 경우 많은 OS 가 이를 재결합하려고 시도함 . 이때 문제 발생 가능 . 아래의 공격이 가능 1.. 단순한 DOS 2. 정보 은폐 공격 : 바이러스 탐지기나 침입탐지 시스템을 우회 가능 3. 두 번째 fragment 의 헤더를 검사하지 않고 그대로 전달 : 공격자가 블록된 포트의 정보획득 가능
The ZIP file format is a popular data compression and archival format . A ZIP file contains one or more files that have been compressed, to reduce their file size, or stored as-is. Multipurpose Internet Mail Extensions ( MIME ) is an Internet Standard that extends the format of e-mail to support text in character sets other than US-ASCII , non-text attachments, multi-part message bodies, and header information in non-ASCII character sets. Virtually all human-written Internet e-mail and a fairly large proportion of automated e-mail is transmitted via SMTP in MIME format. Internet e-mail is so closely associated with the SMTP and MIME standards that it is sometimes called SMTP/MIME e-mail.
Perimeter network is another layer of security.
SOCKS is an Internet protocol that allows client-server applications to transparently use the services of a network firewall . SOCKS is an abbreviation for &quot;SOCKetS&quot;  . Clients behind a firewall, willing to access exterior servers, may connect to a SOCKS proxy server instead. Such proxy server controls the eligibility of the client to access the external server and passes the request on to the server. SOCKS can also be used in the opposite way, allowing the clients outside the firewall (&quot;exterior clients&quot;) connect to servers inside the firewall (internal servers). The protocol was originally developed by David Koblas, a system administrator of MIPS Computer Systems . After MIPS was taken over by Silicon Graphics in 1992, Koblas presented a paper on SOCKS at that year's Usenix Security Symposium and SOCKS became publicly available.  The protocol was extended to version 4 by Ying-Da Lee of NEC . Transfers user info from the SOCKS client to the SOCKS server for user authentication Authenticates the user and the channel Guarantees the integrity of TCP and UDP channels
Created in 1997, Solsoft is the leading provider of security policy management solutions, enabling businesses to quickly deploy and update error-proof security policies across their global networks.
Securify delivers real-time identity aware security monitoring and controls for critical business systems. Our solutions continuously verify that insiders are doing what they are supposed to according to your business intent and best practices.
Transitions to wrong are omitted. Dashed line indicates interprocedural edges.
Samba is software that can be run on a platform other than Microsoft Windows, for example, UNIX, Linux, IBM System 390, OpenVMS, and other operating systems. Samba uses the TCP/IP protocol that is installed on the host server. When correctly configured, it allows that host to interact with a Microsoft Windows client or server as if it is a Windows file and print server. From The Official Samba
Intrusion Detection Expert System (IDES )
AFIWC Air Force Information Warfare Center
A device that filters all traffic between inside network and outside network
protect a private network against intrusion
prevent unnoticed and unauthorized export of proprietary information.
Firewalls John Mitchell Credit: some text, illustrations from Simon Cooper May 20, 2004
Firewall is a special form of a reference monitor.
small and simple enough for rigorous analysis
TCP Protocol Stack Application Transport Network Link Application protocol TCP, UDP protocol IP protocol Data Link IP Network Access IP protocol Data Link Application Transport Network Link Transport layer provides ports , logical channels identified by number
Data Formats Application Transport (TCP, UDP) Network (IP) Link Layer Application message - data TCP data TCP data TCP data TCP Header data TCP IP IP Header data TCP IP ETH ETF Link (Ethernet) Header Link (Ethernet) Trailer segment packet frame message
Telnet “ PORT 1234” “ ACK” Telnet Client Telnet Server 23 1234 Client opens channel to server; tells server its port number. The ACK bit is not set while establishing the connection but will be set on the remaining packets Server acknowledges
FTP FTP Client FTP Server Client opens command channel to server; tells server second port number Server acknowledges Server opens data channel to client’s second port Client acknowledges “ PORT 5151” “ OK” DATA CHANNEL TCP ACK 20 Data 21 Command 5150 5151
Network Address Translation (NAT) Port & Address Translation (PAT)