CVE-2018-5784 (published 2018-01-19T08:29Z)

In LibTIFF 4.0.9, there is an uncontrolled resource consumption in the TIFFSetDirectory function of tif_dir.c. Remote attackers could leverage this vulnerability to cause a denial of service via a crafted tif file. This occurs because the declared number of directory entries is not validated against the actual number of directory entries.

Severity: MEDIUM
CVSS v2 base score: 4.3 (AV:N/AC:M/Au:N/C:N/I:N/A:P)
CVSS v3 base score: 6.5, MEDIUM (CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H)

Weakness information:
cwe_id: CWE-400
cwe_name: Uncontrolled Resource Consumption
description: The product does not properly control the allocation and maintenance of a limited resource, thereby enabling an actor to influence the amount of resources consumed, eventually leading to the exhaustion of available resources.
extended_description: 
            Limited resources include memory, file system storage, database connection pool entries, and CPU. If an attacker can trigger the allocation of these limited resources, but the number or size of the resources is not controlled, then the attacker could cause a denial of service that consumes all available resources. This would prevent valid users from accessing the product, and it could potentially have an impact on the surrounding environment. For example, a memory exhaustion attack against an application could slow down the application as well as its host operating system.
            There are at least three distinct scenarios which can commonly lead to resource exhaustion:
               
                  Lack of throttling for the number of allocated resources
                  Losing all references to a resource before reaching the shutdown stage
                  Not closing/returning a resource after processing
               
            Resource exhaustion problems are often result due to an incorrect implementation of the following situations:
               
                  Error conditions and other exceptional circumstances.
                  Confusion over which part of the program is responsible for releasing the resource.
               
         
         

Fix information:
repo_url: https://gitlab.com/libtiff/libtiff
commit_details: repo_url: https://gitlab.com/libtiff/libtiff
author: Nathan Baker
author_date: 2018-02-06 10:13:57-05:00
msg: Fix for bug 2772

It is possible to craft a TIFF document where the IFD list is circular,
leading to an infinite loop while traversing the chain. The libtiff
directory reader has a failsafe that will break out of this loop after
reading 65535 directory entries, but it will continue processing,
consuming time and resources to process what is essentially a bogus TIFF
document.

This change fixes the above behavior by breaking out of processing when
a TIFF document has >= 65535 directories and terminating with an error.
repository: repo_url: https://gitlab.com/libtiff/libtiff
repo_name: visit repo url
description: visit repo url
repo_language: visit repo url
owner: libtiff
file_changes: filename: tif_overview.c
change_type: ModificationType.MODIFY
diff: @@ -65,6 +65,8 @@
 #  define MAX(a,b)      ((a>b) ? a : b)
 #endif
 
+#define TIFF_DIR_MAX  65534
+
 void TIFFBuildOverviews( TIFF *, int, int *, int, const char *,
                          int (*)(double,void*), void * );
 
@@ -91,6 +93,7 @@ uint32 TIFF_WriteOverview( TIFF *hTIFF, uint32 nXSize, uint32 nYSize,
 {
     toff_t	nBaseDirOffset;
     toff_t	nOffset;
+    tdir_t	iNumDir;
 
     (void) bUseSubIFDs;
 
@@ -147,7 +150,16 @@ uint32 TIFF_WriteOverview( TIFF *hTIFF, uint32 nXSize, uint32 nYSize,
         return 0;
 
     TIFFWriteDirectory( hTIFF );
-    TIFFSetDirectory( hTIFF, (tdir_t) (TIFFNumberOfDirectories(hTIFF)-1) );
+    iNumDir = TIFFNumberOfDirectories(hTIFF);
+    if( iNumDir > TIFF_DIR_MAX )
+    {
+        TIFFErrorExt( TIFFClientdata(hTIFF),
+                      "TIFF_WriteOverview",
+                      "File `%s' has too many directories.\n",
+                      TIFFFileName(hTIFF) );
+        exit(-1);
+    }
+    TIFFSetDirectory( hTIFF, (tdir_t) (iNumDir - 1) );
 
     nOffset = TIFFCurrentDirOffset( hTIFF );
 

programming_language: C++
filename: tiff2pdf.c
change_type: ModificationType.MODIFY
diff: @@ -68,6 +68,8 @@ extern int getopt(int, char**, char*);
 
 #define PS_UNIT_SIZE	72.0F
 
+#define TIFF_DIR_MAX    65534
+
 /* This type is of PDF color spaces. */
 typedef enum {
 	T2P_CS_BILEVEL = 0x01,	/* Bilevel, black and white */
@@ -1051,6 +1053,14 @@ void t2p_read_tiff_init(T2P* t2p, TIFF* input){
 	uint16* tiff_transferfunction[3];
 
 	directorycount=TIFFNumberOfDirectories(input);
+	if(directorycount > TIFF_DIR_MAX) {
+		TIFFError(
+			TIFF2PDF_MODULE,
+			"TIFF contains too many directories, %s",
+			TIFFFileName(input));
+		t2p->t2p_error = T2P_ERR_ERROR;
+		return;
+	}
 	t2p->tiff_pages = (T2P_PAGE*) _TIFFmalloc(TIFFSafeMultiply(tmsize_t,directorycount,sizeof(T2P_PAGE)));
 	if(t2p->tiff_pages==NULL){
 		TIFFError(

programming_language: C
filename: tiffcrop.c
change_type: ModificationType.MODIFY
diff: @@ -215,6 +215,8 @@ extern int getopt(int argc, char * const argv[], const char *optstring);
 #define DUMP_TEXT   1
 #define DUMP_RAW    2
 
+#define TIFF_DIR_MAX  65534
+
 /* Offsets into buffer for margins and fixed width and length segments */
 struct offset {
   uint32  tmargin;
@@ -2232,7 +2234,7 @@ main(int argc, char* argv[])
     pageNum = -1;
   else
     total_images = 0;
-  /* read multiple input files and write to output file(s) */
+  /* Read multiple input files and write to output file(s) */
   while (optind < argc - 1)
     {
     in = TIFFOpen (argv[optind], "r");
@@ -2240,7 +2242,14 @@ main(int argc, char* argv[])
       return (-3);
 
     /* If only one input file is specified, we can use directory count */
-    total_images = TIFFNumberOfDirectories(in); 
+    total_images = TIFFNumberOfDirectories(in);
+    if (total_images > TIFF_DIR_MAX)
+      {
+      TIFFError (TIFFFileName(in), "File contains too many directories");
+      if (out != NULL)
+        (void) TIFFClose(out);
+      return (1);
+      }
     if (image_count == 0)
       {
       dirnum = 0;

programming_language: C