Exploitalert - Database of Exploits

Buffer-overflow and crash in Fenice OMS 1.10

CVE	Category	Price	Severity
	CWE-119	Unknown	High

Author	Risk	Exploitation Type	Date
Unknown	Critical	Remote	2006-05-02

CPE
cpe:cpe:/a:fenice:oms:1.10

CVSS	EPSS	EPSSP
CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N	0.02192	0.50148

CVSS vector description

Metric	Value	Metric Description	Value Description
Attack vector	Local	AV	The vulnerable system is not bound to the network stack and the attacker’s path is via read/write/execute capabilities. Either: the attacker exploits the vulnerability by accessing the target system locally (e.g., keyboard, console), or through terminal emulation (e.g., SSH); or the attacker relies on User Interaction by another person to perform actions required to exploit the vulnerability (e.g., using social engineering techniques to trick a legitimate user into opening a malicious document).
Attack Complexity	Low	AC	The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Attack Requirements	Present	AT	The successful attack depends on the presence of specific deployment and execution conditions of the vulnerable system that enable the attack. These include: A race condition must be won to successfully exploit the vulnerability. The successfulness of the attack is conditioned on execution conditions that are not under full control of the attacker. The attack may need to be launched multiple times against a single target before being successful. Network injection. The attacker must inject themselves into the logical network path between the target and the resource requested by the victim (e.g. vulnerabilities requiring an on-path attacker).
Privileges Required	Low	PR	The attacker requires privileges that provide basic capabilities that are typically limited to settings and resources owned by a single low-privileged user. Alternatively, an attacker with Low privileges has the ability to access only non-sensitive resources.
User Interaction	None	UI	The vulnerable system can be exploited without interaction from any human user, other than the attacker. Examples include: a remote attacker is able to send packets to a target system a locally authenticated attacker executes code to elevate privileges
Confidentiality Impact to the Vulnerable System	High	VC	There is a total loss of confidentiality, resulting in all information within the Vulnerable System being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact. For example, an attacker steals the administrator's password, or private encryption keys of a web server.
Availability Impact to the Vulnerable System	High	VI	There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the Vulnerable System. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the Vulnerable System.
Availability Impact to the Vulnerable System	High	VA	There is a total loss of availability, resulting in the attacker being able to fully deny access to resources in the Vulnerable System; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the Vulnerable System (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).
Subsequent System Confidentiality Impact	Negligible	SC	There is no loss of confidentiality within the Subsequent System or all confidentiality impact is constrained to the Vulnerable System.
Integrity Impact to the Subsequent System	None	SI	There is no loss of integrity within the Subsequent System or all integrity impact is constrained to the Vulnerable System.
Availability Impact to the Subsequent System	None	SA	There is no loss of availibility within the Subsequent System or all availibility impact is constrained to the Vulnerable System.

http://cxsecurity.com/ascii/WLB-2006040115

####################################################################### Luigi Auriemma Application: Fenice - Open Media Streaming Server http://streaming.polito.it/server Versions: <= 1.10 and current SVN 2005-07-26 Platforms: *nix, *BSD and others Bugs: A] buffer-overflow in parse_url B] crash in RTSP_msg_len Exploitation: remote Date: 23 Apr 2006 Author: Luigi Auriemma e-mail: aluigi (at) autistici (dot) org [email concealed] web: http://aluigi.altervista.org ####################################################################### 1) Introduction 2) Bugs 3) The Code 4) Fix ####################################################################### =============== 1) Introduction =============== Fenice is the name of the Open Media Streaming Server (OMS) developed by the italian team of the Politecnico di Torino University. This open source server implements the RTSP, RTP and RTCP protocols. ####################################################################### ======= 2) Bugs ======= ------------------------------- A] buffer-overflow in parse_url ------------------------------- The RTSP module of Fenice uses a function (parse_url) for retrieving the server, the port and the filename contained in the URI sent by the client. This function uses some strcpy calls for filling the server and file_name buffers passed by the main function allowing an attacker to use the consequent buffer-overflow vulnerability for executing possible malicious code. From rtsp/parse_url.c: int parse_url(const char *url, char *server, unsigned short *port, char *file_name) // Note: this routine comes from OMS { /* expects format '[rtsp://server[:port/]]filename' */ ... strcpy(server, token); ... token = strtok(NULL, " "); if (token) strcpy(file_name, token); ... char *token = strtok(full, " tn"); if (token) { strcpy(file_name, token); server[0] = ''; valid_url = 1; } } free(full); return valid_url; } ------------------------ B] crash in RTSP_msg_len ------------------------ The function which handles the Content-Length field sent by the client doesn't check the size/sign of this parameter. In the function RTSP_msg_len we can see the ml variable used to contain the number of bytes in the header and bl for the Content-Length value. When the end of the client's request is reached the program adds bl to ml. If bl (Content-Length) is a big value like 2147483647 or more ml will become a negative number (ml is a signed integer like all the other variables there) and the subsequent check "ml > rtsp->in_size" will be bypassed. The result is the reading access to an invalid zone of the memory which will cause the immediate crash of the server. From rtsp/RTSP_msg_len.c: void RTSP_msg_len(int *hdr_len, int *body_len, RTSP_buffer * rtsp) // This routine is from OMS. { int eom;/* end of message found */ int mb;/* message body exists */ int tc;/* terminator count */ int ws;/* white space */ int ml;/* total message length including any message body */ int bl;/* message body length */ char c;/* character */ char *p; eom = mb = ml = bl = 0; while (ml <= rtsp->in_size) { ... if (eom) { ml += bl;/* add in the message body length */ break;/* all done finding the end of the message. */ } if (ml >= rtsp->in_size) break; ... if (sscanf(&(rtsp->in_buffer[ml]), "%d", &bl) != 1) { fnc_log(FNC_LOG_FATAL,"invalid ContentLength encountered in message."); exit(-1); } } } } if (ml > rtsp->in_size) { fnc_log(FNC_LOG_FATAL,"buffer did not contain the entire RTSP message."); exit(-1); } ... *hdr_len = ml - bl; for (tc = rtsp->in_size - ml, p = &(rtsp->in_buffer[ml]); tc && (*p == ''); p++, bl++, tc--); *body_len = bl; } ####################################################################### =========== 3) The Code =========== A] GET /[about 320 'a's] HTTP/1.0 B] GET / HTTP/1.0 Content-Length: 4294967295 ####################################################################### ====== 4) Fix ====== A patch will be released soon. ####################################################################### --- Luigi Auriemma http://aluigi.altervista.org

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