CVE-2016-5357 (published 2016-08-07T16:59Z)

wiretap/netscreen.c in the NetScreen file parser in Wireshark 1.12.x before 1.12.12 and 2.x before 2.0.4 mishandles sscanf unsigned-integer processing, which allows remote attackers to cause a denial of service (application crash) via a crafted file.

Severity: MEDIUM
CVSS v2 base score: 4.3 (AV:N/AC:M/Au:N/C:N/I:N/A:P)
CVSS v3 base score: 5.9, MEDIUM (CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H)

Weakness information:
cwe_id: CWE-20
cwe_name: Improper Input Validation
description: The product receives input or data, but it does
        not validate or incorrectly validates that the input has the
        properties that are required to process the data safely and
        correctly.
extended_description: 
	   Input validation is a frequently-used technique
	   for checking potentially dangerous inputs in order to
	   ensure that the inputs are safe for processing within the
	   code, or when communicating with other components.  When
	   software does not validate input properly, an attacker is
	   able to craft the input in a form that is not expected by
	   the rest of the application. This will lead to parts of the
	   system receiving unintended input, which may result in
	   altered control flow, arbitrary control of a resource, or
	   arbitrary code execution.
	   Input validation is not the only technique for
	   processing input, however.  Other techniques attempt to
	   transform potentially-dangerous input into something safe, such
	   as filtering (CWE-790) - which attempts to remove dangerous
	   inputs - or encoding/escaping (CWE-116), which attempts to
	   ensure that the input is not misinterpreted when it is included
	   in output to another component. Other techniques exist as well
	   (see CWE-138 for more examples.)
	   Input validation can be applied to:
	   
	     raw data - strings, numbers, parameters, file contents, etc.
	     metadata - information about the raw data, such as headers or size
	   
	   Data can be simple or structured.  Structured data
	   can be composed of many nested layers, composed of
	   combinations of metadata and raw data, with other simple or
	   structured data.
	   Many properties of raw data or metadata may need
	   to be validated upon entry into the code, such
	   as:
	   
	     specified quantities such as size, length, frequency, price, rate, number of operations, time, etc.
	     implied or derived quantities, such as the actual size of a file instead of a specified size
	     indexes, offsets, or positions into more complex data structures
	     symbolic keys or other elements into hash tables, associative arrays, etc.
	     well-formedness, i.e. syntactic correctness - compliance with expected syntax 
	     lexical token correctness - compliance with rules for what is treated as a token
	     specified or derived type - the actual type of the input (or what the input appears to be)
	     consistency - between individual data elements, between raw data and metadata, between references, etc.
	     conformance to domain-specific rules, e.g. business logic 
	     equivalence - ensuring that equivalent inputs are treated the same
	     authenticity, ownership, or other attestations about the input, e.g. a cryptographic signature to prove the source of the data
	   
	   Implied or derived properties of data must often
	   be calculated or inferred by the code itself.  Errors in
	   deriving properties may be considered a contributing factor
	   to improper input validation.
	   
	   Note that "input validation" has very different
	   meanings to different people, or within different
	   classification schemes.  Caution must be used when
	   referencing this CWE entry or mapping to it.  For example,
	   some weaknesses might involve inadvertently giving control
	   to an attacker over an input when they should not be able
	   to provide an input at all, but sometimes this is referred
	   to as input validation.
	   Finally, it is important to emphasize that the
	   distinctions between input validation and output escaping
	   are often blurred, and developers must be careful to
	   understand the difference, including how input validation
	   is not always sufficient to prevent vulnerabilities,
	   especially when less stringent data types must be
	   supported, such as free-form text. Consider a SQL injection
	   scenario in which a person's last name is inserted into a
	   query. The name "O'Reilly" would likely pass the validation
	   step since it is a common last name in the English
	   language. However, this valid name cannot be directly
	   inserted into the database because it contains the "'"
	   apostrophe character, which would need to be escaped or
	   otherwise transformed. In this case, removing the
	   apostrophe might reduce the risk of SQL injection, but it
	   would produce incorrect behavior because the wrong name
	   would be recorded.
       
         

Fix information:
repo_url: https://github.com/wireshark/wireshark
commit_details: repo_url: https://github.com/wireshark/wireshark
author: Guy Harris
author_date: 2016-05-01 16:13:31-07:00
msg: Don't treat the packet length as unsigned.

The scanf family of functions are as annoyingly bad at handling unsigned
numbers as strtoul() is - both of them are perfectly willing to accept a
value beginning with a negative sign as an unsigned value.  When using
strtoul(), you can compensate for this by explicitly checking for a '-'
as the first character of the string, but you can't do that with
sscanf().

So revert to having pkt_len be signed, and scanning it with %d, but
check for a negative value and fail if we see a negative value.

Bug: 12396
Change-Id: I54fe8f61f42c32b5ef33da633ece51bbcda8c95f
Reviewed-on: https://code.wireshark.org/review/15220
Reviewed-by: Guy Harris <guy@alum.mit.edu>
repository: repo_url: https://github.com/wireshark/wireshark
repo_name: wireshark/wireshark
description: Read-only mirror of Wireshark's Git repository at https://gitlab.com/wireshark/wireshark. ⚠️ GitHub won't let us disable pull requests. ⚠️ THEY WILL BE IGNORED HERE ⚠️ Upload them at GitLab instead.
repo_language: C
owner: wireshark
file_changes: filename: netscreen.c
change_type: ModificationType.MODIFY
diff: @@ -263,28 +263,33 @@ static gboolean
 parse_netscreen_packet(FILE_T fh, struct wtap_pkthdr *phdr, Buffer* buf,
     char *line, int *err, gchar **err_info)
 {
+	int		pkt_len;
 	int		sec;
 	int		dsec;
 	char		cap_int[NETSCREEN_MAX_INT_NAME_LENGTH];
 	char		direction[2];
-	guint		pkt_len;
 	char		cap_src[13];
 	char		cap_dst[13];
 	guint8		*pd;
 	gchar		*p;
 	int		n, i = 0;
-	guint		offset = 0;
+	int		offset = 0;
 	gchar		dststr[13];
 
 	phdr->rec_type = REC_TYPE_PACKET;
 	phdr->presence_flags = WTAP_HAS_TS|WTAP_HAS_CAP_LEN;
 
-	if (sscanf(line, "%9d.%9d: %15[a-z0-9/:.-](%1[io]) len=%9u:%12s->%12s/",
+	if (sscanf(line, "%9d.%9d: %15[a-z0-9/:.-](%1[io]) len=%9d:%12s->%12s/",
 		   &sec, &dsec, cap_int, direction, &pkt_len, cap_src, cap_dst) < 5) {
 		*err = WTAP_ERR_BAD_FILE;
 		*err_info = g_strdup("netscreen: Can't parse packet-header");
 		return -1;
 	}
+	if (pkt_len < 0) {
+		*err = WTAP_ERR_BAD_FILE;
+		*err_info = g_strdup("netscreen: packet header has a negative packet length");
+		return FALSE;
+	}
 	if (pkt_len > WTAP_MAX_PACKET_SIZE) {
 		/*
 		 * Probably a corrupt capture file; don't blow up trying

programming_language: C
repo_url: https://github.com/wireshark/wireshark
commit_details: repo_url: https://github.com/wireshark/wireshark
author: Guy Harris
author_date: 2016-04-29 17:08:11-07:00
msg: Fix packet length handling.

Treat the packet length as unsigned - it shouldn't be negative in the
file.  If it is, that'll probably cause the sscanf to fail, so we'll
report the file as bad.

Check it against WTAP_MAX_PACKET_SIZE to make sure we don't try to
allocate a huge amount of memory, just as we do in other file readers.

Use the now-validated packet size as the length in
ws_buffer_assure_space(), so we are certain to have enough space, and
don't allocate too much space.

Merge the header and packet data parsing routines while we're at it.

Bug: 12396
Change-Id: I7f981f9cdcbea7ecdeb88bfff2f12d875de2244f
Reviewed-on: https://code.wireshark.org/review/15176
Reviewed-by: Guy Harris <guy@alum.mit.edu>
repository: repo_url: https://github.com/wireshark/wireshark
repo_name: wireshark/wireshark
description: Read-only mirror of Wireshark's Git repository at https://gitlab.com/wireshark/wireshark. ⚠️ GitHub won't let us disable pull requests. ⚠️ THEY WILL BE IGNORED HERE ⚠️ Upload them at GitLab instead.
repo_language: C
owner: wireshark
file_changes: filename: netscreen.c
change_type: ModificationType.MODIFY
diff: @@ -69,12 +69,8 @@ static gboolean netscreen_read(wtap *wth, int *err, gchar **err_info,
 static gboolean netscreen_seek_read(wtap *wth, gint64 seek_off,
 	struct wtap_pkthdr *phdr, Buffer *buf,
 	int *err, gchar **err_info);
-static int parse_netscreen_rec_hdr(struct wtap_pkthdr *phdr, const char *line,
-	char *cap_int, gboolean *cap_dir, char *cap_dst,
-	int *err, gchar **err_info);
-static gboolean parse_netscreen_hex_dump(FILE_T fh, int pkt_len,
-	const char *cap_int, const char *cap_dst, struct wtap_pkthdr *phdr,
-	Buffer* buf, int *err, gchar **err_info);
+static gboolean parse_netscreen_packet(FILE_T fh, struct wtap_pkthdr *phdr,
+	Buffer* buf, char *line, int *err, gchar **err_info);
 static int parse_single_hex_dump_line(char* rec, guint8 *buf,
 	guint byte_offset);
 
@@ -191,27 +187,16 @@ static gboolean netscreen_read(wtap *wth, int *err, gchar **err_info,
     gint64 *data_offset)
 {
 	gint64		offset;
-	int		pkt_len;
 	char		line[NETSCREEN_LINE_LENGTH];
-	char		cap_int[NETSCREEN_MAX_INT_NAME_LENGTH];
-	gboolean	cap_dir;
-	char		cap_dst[13];
 
 	/* Find the next packet */
 	offset = netscreen_seek_next_packet(wth, err, err_info, line);
 	if (offset < 0)
 		return FALSE;
 
-	/* Parse the header */
-	pkt_len = parse_netscreen_rec_hdr(&wth->phdr, line, cap_int, &cap_dir,
-	    cap_dst, err, err_info);
-	if (pkt_len == -1)
-		return FALSE;
-
-	/* Convert the ASCII hex dump to binary data, and fill in some
-	   struct wtap_pkthdr fields */
-	if (!parse_netscreen_hex_dump(wth->fh, pkt_len, cap_int,
-	    cap_dst, &wth->phdr, wth->frame_buffer, err, err_info))
+	/* Parse the header and convert the ASCII hex dump to binary data */
+	if (!parse_netscreen_packet(wth->fh, &wth->phdr,
+	    wth->frame_buffer, line, err, err_info))
 		return FALSE;
 
 	/*
@@ -239,11 +224,7 @@ netscreen_seek_read(wtap *wth, gint64 seek_off,
 	struct wtap_pkthdr *phdr, Buffer *buf,
 	int *err, gchar **err_info)
 {
-	int		pkt_len;
 	char		line[NETSCREEN_LINE_LENGTH];
-	char		cap_int[NETSCREEN_MAX_INT_NAME_LENGTH];
-	gboolean	cap_dir;
-	char		cap_dst[13];
 
 	if (file_seek(wth->random_fh, seek_off, SEEK_SET, err) == -1) {
 		return FALSE;
@@ -257,15 +238,8 @@ netscreen_seek_read(wtap *wth, gint64 seek_off,
 		return FALSE;
 	}
 
-	pkt_len = parse_netscreen_rec_hdr(phdr, line, cap_int, &cap_dir,
-	    cap_dst, err, err_info);
-	if (pkt_len == -1)
-		return FALSE;
-
-	if (!parse_netscreen_hex_dump(wth->random_fh, pkt_len, cap_int,
-	    cap_dst, phdr, buf, err, err_info))
-		return FALSE;
-	return TRUE;
+	return parse_netscreen_packet(wth->random_fh, phdr, buf, line,
+	    err, err_info);
 }
 
 /* Parses a packet record header. There are a few possible formats:
@@ -285,49 +259,54 @@ netscreen_seek_read(wtap *wth, gint64 seek_off,
 
 
  */
-static int
-parse_netscreen_rec_hdr(struct wtap_pkthdr *phdr, const char *line, char *cap_int,
-    gboolean *cap_dir, char *cap_dst, int *err, gchar **err_info)
+static gboolean
+parse_netscreen_packet(FILE_T fh, struct wtap_pkthdr *phdr, Buffer* buf,
+    char *line, int *err, gchar **err_info)
 {
-	int	sec;
-	int	dsec, pkt_len;
-	char	direction[2];
-	char	cap_src[13];
+	int		sec;
+	int		dsec;
+	char		cap_int[NETSCREEN_MAX_INT_NAME_LENGTH];
+	char		direction[2];
+	guint		pkt_len;
+	char		cap_src[13];
+	char		cap_dst[13];
+	guint8		*pd;
+	gchar		*p;
+	int		n, i = 0;
+	guint		offset = 0;
+	gchar		dststr[13];
 
 	phdr->rec_type = REC_TYPE_PACKET;
 	phdr->presence_flags = WTAP_HAS_TS|WTAP_HAS_CAP_LEN;
 
-	if (sscanf(line, "%9d.%9d: %15[a-z0-9/:.-](%1[io]) len=%9d:%12s->%12s/",
+	if (sscanf(line, "%9d.%9d: %15[a-z0-9/:.-](%1[io]) len=%9u:%12s->%12s/",
 		   &sec, &dsec, cap_int, direction, &pkt_len, cap_src, cap_dst) < 5) {
 		*err = WTAP_ERR_BAD_FILE;
 		*err_info = g_strdup("netscreen: Can't parse packet-header");
 		return -1;
 	}
+	if (pkt_len > WTAP_MAX_PACKET_SIZE) {
+		/*
+		 * Probably a corrupt capture file; don't blow up trying
+		 * to allocate space for an immensely-large packet.
+		 */
+		*err = WTAP_ERR_BAD_FILE;
+		*err_info = g_strdup_printf("netscreen: File has %u-byte packet, bigger than maximum of %u",
+		    pkt_len, WTAP_MAX_PACKET_SIZE);
+		return FALSE;
+	}
 
-	*cap_dir = (direction[0] == 'o' ? NETSCREEN_EGRESS : NETSCREEN_INGRESS);
+	/*
+	 * If direction[0] is 'o', the direction is NETSCREEN_EGRESS,
+	 * otherwise it's NETSCREEN_INGRESS.
+	 */
 
 	phdr->ts.secs  = sec;
 	phdr->ts.nsecs = dsec * 100000000;
 	phdr->len = pkt_len;
 
-	return pkt_len;
-}
-
-/* Converts ASCII hex dump to binary data, and fills in some struct
-   wtap_pkthdr fields.  Returns TRUE on success and FALSE on any error. */
-static gboolean
-parse_netscreen_hex_dump(FILE_T fh, int pkt_len, const char *cap_int,
-    const char *cap_dst, struct wtap_pkthdr *phdr, Buffer* buf,
-    int *err, gchar **err_info)
-{
-	guint8	*pd;
-	gchar	line[NETSCREEN_LINE_LENGTH];
-	gchar	*p;
-	int	n, i = 0, offset = 0;
-	gchar	dststr[13];
-
 	/* Make sure we have enough room for the packet */
-	ws_buffer_assure_space(buf, NETSCREEN_MAX_PACKET_LEN);
+	ws_buffer_assure_space(buf, pkt_len);
 	pd = ws_buffer_start_ptr(buf);
 
 	while(1) {
@@ -373,7 +352,7 @@ parse_netscreen_hex_dump(FILE_T fh, int pkt_len, const char *cap_int,
 		/* If there is no more data and the line was not empty,
 		 * then there must be an error in the file
 		 */
-		if(n == -1) {
+		if (n == -1) {
 			*err = WTAP_ERR_BAD_FILE;
 			*err_info = g_strdup("netscreen: cannot parse hex-data");
 			return FALSE;
@@ -385,7 +364,7 @@ parse_netscreen_hex_dump(FILE_T fh, int pkt_len, const char *cap_int,
 		/* If there was more hex-data than was announced in the len=x
 		 * header, then then there must be an error in the file
 		 */
-		if(offset > pkt_len) {
+		if (offset > pkt_len) {
 			*err = WTAP_ERR_BAD_FILE;
 			*err_info = g_strdup("netscreen: too much hex-data");
 			return FALSE;

programming_language: C
filename: netscreen.h
change_type: ModificationType.MODIFY
diff: @@ -46,9 +46,6 @@
 #define NETSCREEN_INGRESS		FALSE
 #define NETSCREEN_EGRESS		TRUE
 
-
-#define NETSCREEN_MAX_PACKET_LEN	65536
-
 wtap_open_return_val netscreen_open(wtap *wth, int *err, gchar **err_info);
 
 #endif

programming_language: C